# Domesticating the Gambusia



## PaulLamb

Livebearers are a favorite of beginning aquarium hobbiests, because of their diversity, hardiness, and relative ease of care. One livebearer, however, has a bad reputation for being a nuisance, ugly, mean, and aggressive - the so-called mosquitofish - Gambusia affinis.

But if you take the time to study this fish, it is actually quite amazing as livebearers go. They have conquered a truly astounding variety of habitats all across the globe. The main reason for their success is the fact that they are extremely hardy, thriving even in low oxygen, high salinities (up to twice that of seawater), and a wide range of temperatures (>0 - 42C).

There are probably a number of reasons the Gambusia has not yet been bred for looks, but I think a big fear is that new aquariumists would aquire them, and then tire of them after realizing how agressive they are. This could possibly lead to people dumping them into the wild to wreak havoc on ecosystems that are not already plagued by wild Gambusias. Because of this, I've decided to see if it is possible to domesticate Gambusia affinis. 

Similar projects have been done on a variety of aggressive species (a well-documented recent example is Dmitri Belyaev's successful 50-year silver fox project). However, there is very little information available about the selective breeding of fish for behavioral changes, so I think it would be exciting to contribute to this field. The purpose of this project will be to take the wild, aggressive Gambusia affinis and through selective breeding, turn it into a calm, lovable community fish. It will require coming up with creative ways to guage aggressiveness and track the genetics of fish behavior. I will provide updates on my progress, and make the data I gather available for anyone interested.


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## PaulLamb

I have been giving some thought to the problem of defining aggression in Gambusias. It seems that there are a couple of categories that I should look at.

The first category is how they interact amongst themselves. This breaks down into three subcategories:
- How males compete with eachother for females
- How females defend themselves against amorous males
- Pecking rank (larger, healthier individuals vs. smaller, weaker individuals).

The second category is how they interact with other species of fish. This may or may not be related to pecking rank among themselves.

Actually measuring these types of aggression in a way that produces comparable, reliable numbers may be difficult. My first idea is to isolate individuals for some time until they become comfortable and territoral. I will then introduce a new fish and count the number of times the first fish rushes the newcomer in the space of 5 minutes. I will repeat this test numerous times with each fish to determine if the results are at all reliable.

If anyone else can think of other possible methods for measuring aggression, let me know.


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## bmlbytes

I think the aggression toward other fish is probably more important. People have been able to manage aggression levels within a species for a long time (for instance, the betta fish). I would be interested in seeing if it is even possible to breed out the aggression genes in a fish species.


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## emc7

You could put a fish in a glass jar and see if they attack it. It might more reproducible than watching a fish in a whole tank and you could aim a video camera at it.


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## PaulLamb

I like the idea of a small container, and it would be preferable if the fish didn't actually have to be in contact with eachother. I think a custom observation table made of plexiglass might be the best option. It would consist of two small, thin containers just large enough for the fish to fit in, seperated by glass. The camera would be some constant distance and angle for taking photos or video for each fish. This would make it simple to take consistant measurements for comparison between individual fish. I'm not a great artist, but the basic setup would be something like this:


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## mousey

Had gambusia affinis once-- beautiful coloration but what a nasty girl! And she dropped 55 fry on me one night. Couldnot keep her in the community tank as she chased everything in sight.
They are now illegal in Ontario canada because they can probably live near water culverts where it is a bit warmer.
it would be great though to get the aggression out of them as they really have nice markings.


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## Mikaila31

IMO it would be harder than the Silver Fox experiment. Fish are in a sense "lower" organisms than a fox is comparing their mental and cognitive capabilities. IMO very few fish show any cognitive ability (don't confuse conditioning with cognition here). Foxes you can train relatively easily. The fox can reason against its instincts. The ability to do this would greatly speed up the process. 

Fish can't. Sure its easy to condition them to come to you for food. This is different though. Trying to influence their social behavior. If you could provide some negative reinforcement every time they showed aggression it might work. You can't keep them together though, at least if you want accurate results. (all the foxes were housed individually) If you house a normal gambusia with a much less aggressive one, the mellower one would be affected by the aggression of the other fish. Two could happen, the less aggressive fish will become aggressive in a attempt to compete/survive. Or it will hide constantly and deal with the stress of attacked by the more aggressive fish. Which is why they should be kept individually. Cull the more aggression ones and breed the others. You then also face issues with inbreeding at some point.


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## PaulLamb

It is certainly possible that breeding aggression out of a fish may be more difficult than breeding it out of silver foxes, but it is, of course, speculation until someone tries it.

As for the cognative abilities of foxes speeding up the process, I highly doubt it - the silver fox experiment was not about classical conditioning or training as you suggest. It was about selective breeding to eliminate the aggression that is genetically inherant to the wild silver fox - i.e. to domesticate the species, not to train individuals to be nice.

As for keeping individual fish seperate, that is actually my intention for this experiment. I've designed a custom breeding tank with numerous seperate compartments for individuals. Some of the compartments have smaller birthing compartments for pregnant mothers to give birth. It has an automatic feeding and waterchanging system. I am also writing software for tracking lineages and recording important observations and genetic information (computer programming is another of my hobbies). All of this will not only allow me to keep individuals seperate but also to keep track of each individual fish and decide which pairs are more likely to produce the desired traits in their offspring.

The problem of inbreeding is one that is faced by virtually everyone who embarks on a selective breeding project, and it is something that I will definitely have to deal with. While on vacation across the country, I plan to acquire some Gambusia affinis from a lake here in Kansas where I know there is a thriving population of them. I will join these with the ones I caught from a local pond back home in Maryland. This will ensure that I have a genetically diverse population to start with. After that, it will be a matter of documenting and tracking any negative genetic defects that pop up to ensure that they are not introduced into the breeding line.


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## emc7

You should keep multiple lines. The classic anti-inbreeding strategy in livebearers is to keep two separate lines and cross them to each other (all A fish to B fish) no oftener than ever 2 generation. So brother/sister, father/daughter breeding does occur. But every 2 or 3 or 4 generations you force a no closer than 1st cousin breeding for all the fish. Maintaining genetic diversity, while cultivating a specific trait is an old problem and there are lots of documented strategies you can read about.


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## PaulLamb

I will definitely use some strategy like that. It is still going to be some time before I begin the actual selective breeding process (I want to gather some baseline data first, and make sure there aren't any diseases or genetic problems with the fish I have). In the mean time, I will also be doing a lot of research into the various selective breeding strategies that are used, and I'll probably be posting a few questions here as well when I become more versed on the subject.


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## PaulLamb

I've been reading as much information as I can find about domestication, and I keep coming across the term "neoteny", which many scientists believe is an essential part of domestication. It is a natural process by which adult specimens, through random mutations, retain traits previously seen only in juveniles while at the same time still reaching sexual maturity. It is believed that in species where agressive behaviors begin at a later stage in live, the development of those behaviors can be postponed and eventually eliminated entirely through selective breeding. There are many pieces of evidence to support this theory. For example, there other juvenile-wolf traits found in dogs, like unusually broad skulls, whining, barking, and submissiveness. The data from the silver fox experiment I mentioned above also supports the theory of neoteny being essential for domestication.

So I'm wondering if this process could be applied to the Gambusia. First, I will have to determine if Gambusia fry are aggressive towards other similarly-sized fish/fry. If not, then determining the age at which fry develop aggressive behavior toward other fish and selective breeding to extend that age might be an easier and more reliable way to achieve my goal. Or I could selective breed for both traits, thus applying pressure from two different directions.


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## mousey

if it is any help- I found the fry squabbled from day one much as do baby guppies. However where I find guppies don't continue unless they are having a snit about food, the gambusia fry were much more aggressive to each other CONSTANTLY.
Several folk have commented on different forums that if you throw a dozen gambusia in a rain barrel you will only have 1 fish at the end of the season.


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## PaulLamb

Thanks for the tip, mousey. If you're right, then of course neoteny could not be used in my project, since the premise would be that aggression develops some time after birth. I will do some observations to confirm that aggressive behavior begins from day one, and compare how such behavior changes over time in Gambusias as compared to guppies. It may very well turn out that neoteny can not be used in this case, however I still have my previous strategy to fall back on.

One thing I need to figure out is how many genes are related to aggression in the gambusia. There are most likely more than one (for example four aggression genes have been identified in Africanized honey bees). My initial idea is to use Gambusia/guppy hybrids. If I can get a percentage that are not sterile, I can then cross them back with guppies and count the percentages of agressive to non-aggressive individuals. This ratio should give me a pretty good idea of how many dominant genes there are for aggression.

If that works, I might even be able to take the hybridization a step further. Through careful observation and breeding, I should be able to develop hybrid strains that carry each one of those aggression genes. These strains could be used throughout the project to determine which of the aggression genes are most affected by less-aggressive mutations in my Gambusia breeding lines.


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## emc7

Do you have any gambusia from a real native location and not a feral population? I am finding wild-type cichlids less aggressive than old hobby strains and am wondering if hobbyists haven't been accidentally (take out the chewed fish and keep the aggressor, put them in a small container and breed the survivors) or intentionally (I love to watch this guy kill feeders) selectively breeding for aggression. I am curious if there is a difference in aggression levels in fish from different histories (ponds, tanks, wild-caught).


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## PaulLamb

That's an interesting question. I know Gambusia affinis is a saltwater native from the Gulf of Mexico, but I don't really have any near-term plans to go to that area of the US (I may make a trip to acquire some fish out of curiosity, though). I do know that the wild freshwater affinis population in Kansas has been there a very long time, so they are probably closer to being a native fish (I don't know much about the ones from Maryland, except that they have pretty much replaced the native Gambusia holbrooki, so there could be some wild hybridization going on in that population). I could also buy some Gambusia off of ebay or somewhere and do a comparison of the behavior of each group to see if there are any differences in the level of aggression.

Mousey, you mentioned previously that you once had a Gambusia affinis with beautiful coloration, which I was previously unaware even existed. Where did you get it from? I would be interested in acquiring some of those for comparison as well.


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## TheOldSalt

They do exhibit a small range of colors, from a nice gold to black to a baby blue, and with varying amounts and intensity of the black specks. That's not much to work with, but they will indeed hybridize with guppies and yield partially fertile fry. That's how domestic guppies got their size in the first place, you see; pure guppies are little bitty things. I don't have any info regarding how much color from the guppies can be passed to the Gams.


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## PaulLamb

My initial tests of measuring an individual's aggression in a consistent manner have failed. Firstly, the Gambusias seem to display some amount of intelligence, in that they learn rather quickly that they cannot attack another fish through the glass divider. After a few attempts, they give up. Placing them together in the same container with the bait fish seems to solve that problem, however the measured results range wildly and are in no way consistent. I haven't given up on this idea yet, though. I'll continue experimenting with different setups to see if I can come up with something better. For example, there are numerous factors I need to look at, including time of day the observation takes place, how long the individual has been in the observation container, how many times they've been in the observation container, size/color/temperament of the bait fish, when they were last fed, water temperature, etc.

If I can't get this to work and I can't come up with some other metric for measuring aggression accurately and consistently, the project will become somewhat more difficult -- I'd have to rely on my intuition to decide which individuals are less aggressive than others when choosing breeding pairs.

On another topic, I've been looking at various selective breeding strategies, and the one I think I will use involves four breeding lines and two rotations. Males from Line 1 only breed with females from Line 2, males from 2 with females from 3, etc. On the first cycle, males from rotation A only breed with females from rotation B, and then switch to males from rotation B breeding with females from rotation A on the second cycle. This strategy will help protect genetic diversity by ensuring that breeding pairs are never closer than either second cousins or first cousins once removed. This strategy will also work well for the breeding tanks that I am building, which have eight main compartments - allowing me to use one for each line and rotation.


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## mousey

interesting. Not surprising that they show intelligance.
Most fish are easy to catch the first time they see a net but after that it becomes increasingly difficult. As soon as they see it they go off and hide.
I suppose that altho we say they are an aggressive fish there are various degrees according to the individual personality.


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## PaulLamb

I thought I would give a progress update for this project so far. I have been able to successfully conduct two experiments, and these have revealed some interesting results.

The first experiment was 60-day social interaction experiment to observe how Gambusias interact with other species in a community environment. This experiment involved a 55-gallon aquarium and a 10-gallon.

The 55-gallon represented a large, crowded environment, and consisted of 3 female and 2 male Gambusias, along with 35 - 40 other fish of various species. These included goldfish, rosy reds, swordtails, mollies, and guppies. This tank was purposely overstocked in order to create social pressures to stimulate aggression in the Gambusias.

The 10-gallon represented a frustrated-male environment, and consisted of 3 male Gambusias along with 2 - 4 other fish of various species. The purpose of this aquarium was to observe how males behave when they have no females to pursue.

Over a period of 60 days, I've performed various tests on these two communities, and I've learned quite a lot about Gambusia behavior. Gambusia aggression can be broken down into several predictable patterns:

*1) Hunger*
This is the most visual and predictable motivation for Gambusia aggression. Gambusias have an almost insatiable appetite, and they have the self-image of a much larger fish. To give you an idea of what I'm talking about, say you were to starve a large sailfin molly. After a few days, it might start to look at a juvenile rosy-red as a potential prey item. Gambusias will behave the same way, even though a rosy-red is about the same length as they are. They will simply ram into a fish to stun and kill it, and take small bites out of it rather than swallowing it in one gulp. Just like a large fish would, Gambusias will seek out the smaller, weaker, or injured fish to eat when they are hungry. I believe that hunger is most likely what motivates the aggression that mousey observed in her previous comment "throw a dozen gambusia in a rain barrel you will only have 1 fish at the end of the season". Unless that rain barrel happened to be sitting in the middle of a tropical rain-forest, it is highly unlikely that there would be enough mosquito larva in it to sustain Gambusias for the entire season, I could easily see them start to look at each other as potential prey items when they became hungry. This aggression is also the most preventable. If they are fed twice a day, Gambusias will completely stop hunting other fish for food.

*2) Curiosity*
Gambusias, like many other fish species, become curious when something in their environment changes, such as the addition of a new toy or fish, or a tank-mate behaving oddly because of disease or injury. Gambusia curiosity, however, includes biting. They will not only go up to investigate something interesting, they will also nip at it like sharks do. If the object of their curiosity is weak in some way (such as an injured fish), they may easily badger it to death. When the object of their curiosity is no longer new and interesting, they leave it alone and go back to whatever they were doing before. An important observation: Gambusias find male fancy-guppies to be extremely interesting, and they will absolutely shred them to pieces. Male guppies and Gambusias are totally incompatible in a community environment - the guppy will always end up dead. Female guppies are safe as long as there are enough female Gambusias in the tank to keep the males occupied.

*3) Sex*
This category of aggression is most obvious in the males. Like other livebearer species, the Gambusia males spend every waking hour trying to mate with females. Unlike other species, though, Gambusia sex involves ramming and biting. The females, being much larger and stronger, do not seem to be stressed by this behavior, and tend to hold their own against the amorous males that are constantly after them. When there are no female Gambusias for the males to chase, they will turn their attention to other tank-mates, just like other livebearer males often do. However, the object of their affections may not be able to handle the stress as well as female Gambusias do, and this can result in them being killed. An important observation: swordtails have an aggressive biting behavior similar to Gambusias, except they seem to only use it defensively. This actually makes them excellent tank-mates for Gambusias, because not only are they larger and stronger, but they will turn around and bite back. Even frustrated male Gambusias will quickly learn to leave the swordtails alone.

*3.b) Sex-motivated male pecking-rank*
This is a sub-category of sex-motivated aggression. If there are more males than females in an aquarium, the larger, stronger males will not let the other males come anywhere near them. If there are enough females to go around, this behavior almost completely disappears. The smaller males are smart enough to stay away from whichever females the larger males are chasing after, and they'll go for the other females instead.

*3.c) Sex-defense*
This is a sub-category of sex-motivated aggression. It is seen in the females, and involves turning around and biting a male who is starting to get on her nerves. The male will usually back off for a few seconds before resuming his relentless pursuit.

*4) Pecking-rank*
This aggression is mostly seen when Gambusias are first introduced into a community and at feeding time. Gambusias establish dominance through ramming and biting, and they'll usually end up at the top of the pecking rank even over their much larger tank-mates. Being a naturally schooling species, they do not seem to display any territorial aggression, whether against each other or other species. Pecking rank aggression seems to be used solely for purpose of gaining access to food, and between males for access to females. After the other fish in the tank learn to stay clear of the Gambusias at feeding time, this behavior disappears. Interesting observation: Swordtails are an exception - Gambusias quickly learn to respect them after experiencing their defensive biting behavior.

*5) Birth*
This aggression is the most unpredictable and arguably the most violent. It begins a couple of days before a female is ready to give birth, and ends after she has finished giving birth. It seems to manifest itself in a variety of ways, depending on the personality of the individual fish. Sometimes she will become territorial, and eke out a corner of the aquarium where she will not let any other fish come near without suffering terrible consequences. Other times, she might chase down anyone who is _foolish_ enough to come near the surface of the water. She might guard a particular plant or object in the aquarium. In one case, a female singled out a specific goldfish. Any time she caught a glimpse of him out of the corner of her eye, she'd chase him down and bite him, even if he was all the way on the other side of the tank. His tail was completely shredded by the time she gave birth, and after that she left him alone.

The above experiment was done with the original stock of wild Gambusias I netted here in Maryland. From available documentation, I believe these are most likely affinis/holbrooki hybrids (they are quite a bit more spotty and "colorful" than my other affinis stocks, but not "dalmatian-spotted" like pure holbrooki). I intend to repeat this experiment with wild pure affinis from Kansas and then with native pure holbrooki from Florida, to see if there are any behavior differences.

The second experiment I did yesterday, was to observe the behavior of newborn Gambusia (Maryland affinis/holbrooki) fry who were born last Friday evening. I placed them in the observation container with each-other and with some slightly larger swordtail fry. I tried various combinations and ratios. Interestingly, I did not observe any of the chasing or biting behavior seen in adult Gambusias. I will, of course, need to verify this experiment with other litters and with affinis vs. holbrooki, but this is a significant observation. It means that, at least for this specific litter, aggression actually does not start at day one. If this holds true for all Gambusias, I should be able to use neoteny for this project after all. Also, it won't matter if I am unable to find a reliable way to measure aggression - I just need to be able to observe what age aggressive behavior begins, and choose breeding pairs from those individuals which develop it later.


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## TheOldSalt

Well, I must say that this is turning out to be a lot more interesting than I ever would have guessed.


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## guppyart

another possibility is that with aquarium breeding like you are that they are losing traits the adults had.
I have noticed with a few wild swordtails the original adult males have a speckling of black spots along there body yet 1st generation fry do not have a single spot.
one would think it was a different fish from different parents if they didn't know better..
I am very interested in this study. its proving to be quite interesting and shows what fish might be capable of doing for adaptation.


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## PaulLamb

True, however I tend to be a strong believer in Occam's razor. In this case, I really have no evidence to suggest that the behavior of these fry is abnormal in any way for this particular strain of Gambusia. Of course it is never wise to rule out something just because it seems unlikely. So until I observe some evidence to prove otherwise, I will remain open to the seemingly remote possibility that, as you suggest, I am witnessing punctuated equilibrium here with this particular litter.


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## mousey

it is very interesting to see the results and obviously Paul has been spending a lot of time watching what is going on.

I hope he is not married and expected to help out with chores!
FYI I am female.


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## PaulLamb

mousey said:


> I hope he is not married and expected to help out with chores!


Haha - actually I am married, but my wife happens to be as much of an aquarium nut as I am. I am starting to make a nice bit of supplemental income selling plants and overstock, so hopefully that balances out the neglected chores...



mousey said:


> FYI I am female.


Corrected.


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## PaulLamb

I restarted the social experiment today, this time using the pure affinis. I already see quite a difference in behavior compared to the affinis/holbrooki hybrids.

The most immediately obvious difference is a new aggressive behavior that I can only describe as "don't you turn your back on me!" Any fish they see from the tail end, they will rush up and bite. Goldfish are most vulnerable to this aggression, as they are constantly on the bottom eating food from the gravel, while the affinis tend to hang out near the surface. The motivation for this behavior is not immediately obvious. It doesn't seem to be a territorial issue, as they will completely ignore fish that are swimming right in front of them and instead rush half way across the aquarium to bite another fish who happens to be looking the other way. It doesn't seem to be motivated by hunger either, as they will even do this right after finishing eating. I suppose it may be related to pecking-rank and establishing dominance, but I'll only be able to tell that after they've been in the community for a while.

I'll post an update after I've had time to repeat some of the previous tests and document how these guys behave differently than the affinis/holbrooki hybrids. I'm kind of excited, because I wasn't really expecting them to be so different right from the start.


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## mousey

Paul, I didn't realize there was such a difference in the personality of the holbrooki compared to the affinis.One is mild tempered and one aggressive.
I have been studying pics of the 2 kinds on the internet and neither is completely like the female I had. I fell in love with her because of her size and colors, but gave her back to the store when they became illegal here in Ontario,canada.
My girl had very well outlined scales to the point that they looked lacy; she had lovely speckles in her tail in a ray design and turquois blue in her front fins and in her anal fin.
She came to Big Al's in a shipment of feeder guppies.
When she dropped her 60 fry one night I decided to try a little experiment with them in that I had read they are very tolerant of polluted water. I cycled a small 2 gallon tank with 3 male fry. The water issues were non existant for them and the tank cycled while they grew. they were not too scrappy until they started to get bigger.
Another 3 got put outside in an earthen pot and planted with wild aquatic plants. they survived a raccoon that seemed determined to wash most of my tins I had put out to be recycled.
I gave 40 away to the local aquarium society and have no idea what happened to them afterwards.
I kept 3 females until they started to become scrappy then returned them to Big Al's.
One of the fish room mangers put the fry in a tank by themselves. When I returned the mother the other manager had meltdown because they had recently been banned and he did not want to get caught with them in the store.
I gathered from that that on occasion the game and wildlife people did spot checks on fish stores.
Do you know anything about that?


I am wondering if you are 'just' a hobbyist or do you have some background that would encourage you to submit your findings to a magasine such as Practical Fishkeeping?
I enjoy their research articles.Eg recently a study was done on increased temperature( global warming) on fish aggression, use of the fluid from the sacks of bubble eye goldfish and so forth.
I encourage you to continue your research.
I would love to get another gambusia if they were a bit more mild tempered.
I currently have a couple of female guppies who are 3 1/2 inches long- they are 2 years old now and I will not have them much longer I guess. Am I to understand that big guppies owe their size to gambusia genes?


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## PaulLamb

mousey said:


> One is mild tempered and one aggressive.


Well, I don't know if I'd use the term "mild tempered", but affinis and (probably)affinis/holbrooki hybrids definitely display different kinds of aggression.



mousey said:


> I have been studying pics of the 2 kinds on the internet and neither is completely like the female I had. My girl had very well outlined scales to the point that they looked lacy; she had lovely speckles in her tail in a ray design and turquois blue in her front fins and in her anal fin.


Affinis and holbrooki are by far the most common species (affinis is quickly taking over, but pure holbrooki populations are still common in southeastern states like Florida). However there are several other species of Gambusia out there in the wild, not to mention the aquarium-raised line-bred varieties. From your description, it sounds like you may have had rhyzophorae. I have found some rather nice pictures of various Gambusia varieties. I could definitely see these fish becoming every bit as popular as other livebearers if domestication is possible.



mousey said:


> I gathered from that that on occasion the game and wildlife people did spot checks on fish stores. Do you know anything about that?


I've never heard about that before, but it would make sense from a law enforcement perspective.



mousey said:


> I am wondering if you are 'just' a hobbyist or do you have some background that would encourage you to submit your findings to a magasine such as Practical Fishkeeping?


I'm not looking to be published in any magazine. I do actually have a more specific goal for this project than only research, but have been told by a moderator that I can't discuss it here. So in the interest of not being banned, I won't. 



mousey said:


> Am I to understand that big guppies owe their size to gambusia genes?


There is some debate over that point, but it certainly wouldn't surprise me. Just based on their appearance and some of their behaviors, if it were up to me I would place Gambusias in the genus Poecilia. They certainly seem to be a lot more like guppies than mollies are.


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## PaulLamb

My holbrooki stock arrived in the mail today, and I must say they are absolutely beautiful fish. They look like miniature dalmatian mollies - pale off-whites (greys, blues, and creams) with random black spots covering the fish, and the females are just as nicely patterned as the males. It is really a shame that affinis are starting to wipe out this species from the wild. I don't have enough aquarium space yet to do any social behavior experiments with the holbrooki, at least until I finish building the breeding tanks, so I'll probably just wait until after I finish with the affinis observations.


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## PaulLamb

I haven't finished the affinis social experiments yet, but thought I would post an update, since I've made a couple of interesting observations.

1) The "don't turn your back on me" aggressive behavior I mentioned before is in fact related to pecking rank and establishing dominance in the community. This behavior disappeared after a few days. As with the affinis/holbrooki hybrids, the affinis have established their position as the dominant tank members, and they still respect the swordtails, like the affinis/holbrooki hybrids did.

2) The pure affinis are, in fact, less aggressive than the affinis/holbrooki hybrids were. The main difference is in the hunger aggression. They are considerably less focused in their attack behavior than what I observed in the affinis/holbrooki hybrids. They still become much more aggressive when they are hungry, but they don't seem to single out a single target unless there is a weak or injured fish in the tank.

3) I introduced an adult non-pregnant holbrooki female into the community to see what would happen, and this turned out to be really interesting. For the first few days, she was quite submissive to the affinis, allowing them to bully her. However, after a few days, she became accustomed to the aquarium, and turned into an absolute nightmare. For example, I always feed the fish on the left side of the aquarium, and she quickly learned this fact and became extremely territorial. She mercilessly attacked every fish who came anywhere close to that area of the aquarium. Even when I fed her numerous times a day, she would still single out the smallest, weakest fish in the aquarium and kill and eat them one at a time. After a few days I was forced to remove her from the aquarium, because she was killing everything in sight, including the affinis males. Interestingly, when she returned to an all-holbrooki environment, her personality switched again, and she is living perfectly fine with her holbrooki tank mates.

I have a couple of theories about this observation. One possibility is that holbrooki aggression is directed toward other species (including other Gambusia species) but not toward other holbrooki. Another possibility is that the extreme aggression of this female came about as a result of being over-bullied by the affinis, causing her to just snap. I'll have to do more experiments to know for sure. Another thing to consider is that these holbrooki are an aquarium-raised line-bred strain, while my other Gambusias are wild-caught. This could mean that wild populations are less aggressive than strains that were raised in captivity, as emc7 observed with chichlids.


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## emc7

People have looked at what happens when previously independent bodies of water are connected and similar fish now must compete. In cichlids, it looks like the most territorial fish wins, displacing the others from all the water, and that fish is often a hybrid. So I guess there could well be an evolutionary benefit to being hyper-aggressive toward competing species.


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## PaulLamb

After playing around with different variables, I've found a consistent way to measure aggression in adult fish using the observation container and bait fish method that I described earlier. The following three variables have the most affect on the measurements:

1) Temperature
2) Type of bait fish
3) Time since last feeding

Consistent measurements can be made by making these three variables as consistent as possible. Over a period of 4 days, I have been performing the measurements at 25 Celsius, 1 minute after feeding, and using male guppies of a single color variety for bait fish. I have made 8 consistent measurements each for 6 individual fish (a male and a female of each type).

These are just preliminary observations, but so far, the measurements seem to indicate that the holbrooki are the most aggressive by far, with the affinis/holbrooki hybrids being slightly more aggressive than the pure affinis. Also, females are more aggressive than males. When I have had a chance to measure all of my gambusias, I will post a link to the data for anyone interested. I still need to do some work on my software - besides just making it easier to keep track of lineages, I want it to be able to produce nice graphs based on the raw data for each individual fish, and to provide an interface for attaching things like photos and videos to each fish's record.


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## jaunypic

*what?/*

Wow!! I love fish, but you guys are over my head.... Get a guppy!!!! they are much easier to figure out....LOl (jokin) good luck


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## PaulLamb

I mentioned in an earlier post that I'd like to calculate how many dominant genes are involved in Gambusia aggression by crossing first-generation Gambusia/guppy hybrids back to pure guppies and counting the ratio of offspring that are aggressive. Unfortunately, this is turning out to be a lot more problematic than I anticipated. Starting with several various non-pregnant females, I have been trying for over a month to breed the hybrids, but with no success.

I know this will only work by crossing a male Gambusia with a female guppy (the other way around would absolutely never work). Male Gambusias seem to be most willing to mate with female Endlers or colorless fancy guppies, but these matings have so far resulted in zero pregnancies. I've even tried using mollies and platies instead, on the off chance that one of those species might be more compatible, but still no luck.

I've seen a few different threads on here about successful Gambusia/guppy hybridization. Are there any helpful hints from someone with experience (which Gambusia species, guppy color/variety/age, aquarium size/setup, temp/PH, male/female ratio, etc)?


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## PaulLamb

I noticed today that I may have a possible hybrid pregnancy. I have two females (an affinis and a holbrooki) which, due to lack of aquarium space, I put temporarily in my swordtail community tank to isolate them from Gambusia males until I finish constructing my breeding tanks. They are pretty aggressive in there toward each other of course, but they do seem to respect the swordtails. And I have seen the swordtail males trying to mate with them occasionally. They now both appear to be pregnant (the holbrooki is a little harder to tell due to her spotted coloration, but I am pretty certain about the affinis). Of course, there is a good chance that they are just pregnant from an earlier mating with Gambusia males before they were isolated. I won't be able to tell for sure until they give birth and I can observe the fry as they develop.

The holbrooki female was an adult when I purchased her. The females arrived separately from the males and none appeared to be pregnant at the time, but of course I don't actually know what happened before I got them. The female affinis, however, was from a group of very small fry that I netted in the wild, all of which were immediately isolated from each other even before I was able to sex them. If Gambusias are anything like guppies, they can get pregnant very young, so I certainly won't rule out an earlier mating. But if either of these two females are pregnant by one of the swordtail males, I think the affinis female is the most likely. I'll just have to wait and see.

In the mean time, I will continue to try and achieve Gambusia/guppy hybrids, as that seems to be my best chance of success based on what other hobbyists have done in the past.


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## emc7

Do you think you need to hybridize to make a milder fish? Wouldn't selective breeding for many generations be enough? Or is do you want the hybrids for color?


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## PaulLamb

No, I am not using the hybrids to produce a milder fish. I do have another reason for these hybrids, but can't discuss it here. For the purpose of this topic (domesticating the Gambusia), hybrids will be used to determine how many dominant genes are involved in Gambusia aggression.

The way it will work is like this - I cross Gambusias with another non-aggressive species. Since they get a full set of chromosomes from each parent, these first-generation hybrids will all be aggressive. However, each dominant aggression gene they inherited from their Gambusia parent will be paired with a recessive non-aggression gene from the other parent.

Now, of these first-generation hybrids, a small percentage will (hopefully) not be sterile. I will cross these individuals back to the non-aggressive species. These second-generation hybrids will randomly inherit either dominant aggression genes or recessive non-aggression genes from their first-generation hybrid parent, and of course recessive non-aggression genes from their other parent.

Now I count how many of these second-generation hybrids are aggressive. The ratio of aggressive to non-aggressive can be plugged into a simple formula to calculate how many dominant aggression genes there are. This method will not count recessive or co-dominant aggression genes if there are any.

This information is mainly just to satisfy my curiosity. The domestication project will only involve pure Gambusia lines, not hybrids.


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## emc7

Interesting, thanks for explaining.


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## mousey

do you think they would breed with swords?


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## PaulLamb

mousey said:


> do you think they would breed with swords?


Gambusias and swordtails mate with each other both directions, however the question is whether or not they are genetically compatible and can produce viable fry. I kind of doubt it, really. Gambusia's are much closer to guppies in appearance, so I think they are more genetically similar to the genus Poecilia. They have similar eye orientation, mouth shape, gonopodium anatomy, pregnancy anatomy, and sex differences in size and coloration. Additionally, many Gambusia behaviors are close to guppy behavior as well. Both are top-feeders specialized to preying on surface-breathing mosquito larva, while swordtails are specialized algae-grazers. The females are larger, hardier, and more robust than the males, and they employ similar running, jumping, hiding tactics that protect them and make the males easier targets.

I will just have to wait and see when these unexpected fry arrive whether or not they are hybrids.


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## mousey

well stated and bassically what I was thinking-- but not in such a precise manner


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## PaulLamb

I completed the social interaction experiment with the pure affinis. The basic types of aggression are the same as in the affinis/holbrooki hybrids, but there are a couple of differences.

*1) Hunger*
Pure affinis become more aggressive when they are hungry, and they will attack the smaller fish first. They are considerably less focused or lethal than the affinis/holbrooki hybrids, and it seems less like they are "hunting", and more like they are just overall more "grumpy". As with the hybrids, feeding affinis twice a day seems to be a good way to eliminate this type of aggression.

*2) Curiosity*
There isn't much difference here, except that the pure affinis seem to be less lethal than the hybrids. Male guppies (and colorful females) are still a big "no no".

*3) Sex*
*3.b) Sex-motivated male pecking-rank*
*3.c) Sex-defense*
No differences here.

*4) Pecking-rank*
This category probably best highlights the difference between pure affinis and affinis/holbrooki hybrids. The pure affinis start out considerably more aggressive, and establish their dominance much more quickly than the hybrids do. They chase down and nip any and all fish who expose their tails. After a couple of days of this, they have established a pecking-rank, and the extreme aggressive behavior virtually disappears. They still squabble with the other tank mates at feeding time and males still squabble over females. They are in no way "community fish" by any stretch of the imagination, but overall they are remarkably less aggressive than the hybrids once a pecking-rank is established.

*5) Birth*
No real differences here, either, except the pure affinis seem to be less lethal than the hybrids.

I will not repeat this experiment with the pure holbrooki - they are just WAY too aggressive. I see no reason to subject large numbers of bait fish to constant attack, mutilation, and death, just to come on here and type "Man, these things are aggressive!" Pure holbrooki just really underscore the reason why I'm doing this project in the first place..


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## PaulLamb

My holbrooki female that was potentially pregnant with hybrids died today, probably due to complications as it was her first pregnancy (disappointing for that reason alone, but also because I don't have a whole lot of holbrooki in the first place - at $25 each I spent a small fortune on my breeding stock). The affinis female is still large and healthy (naturally the 10-cent fish makes it - just my luck). I expect her to give birth any day. I'm looking forward to see if they turn out to be hybrids or not. It probably won't take too long to tell - if even slight orange coloration shows up in the babies, I'll know immediately since Gambusias have no orange pigmentation in them at all.

Additionally, one of my female guppies finally survived the male affinis long enough to get pregnant (she's a black segmented yellow-tailed fancy guppy - not a color variety you'd expect to survive the curiosity aggression for very long, but somehow she did). She is pretty beat up and may not survive, but I have her in a nice planted tank and I'll see if I can nurse her back to health. She was separated from her siblings very young and did not appear to be pregnant before introduction into the Gambusia tank, so I'm hopeful she will have some hybrids. The main problem seems to have been that it takes a great deal more time for a successful pregnancy by a male Gambusia than it would by a male guppy, and the females just don't survive long enough. No doubt a major factor is stress caused by the Gambusia male's sexual aggression and curiosity aggression.


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## PaulLamb

The Affinis female who became pregnant in the swordtail tank finally gave birth. She had 5 babies (plus however many she potentially ate), 2 of which died soon after birth. The 3 left, however, definitely have some orange pigmentation in them. I had a little trouble getting a good picture (the camera seems to fade the color at this small a scale), but you can kind of see in this shot:









I am positive now that these are Gambusia/swordtail hybrids. The only other possibility is that the mother had a genetic mutation that caused her to have offspring with orange pigmentation. Considering the circumstances, however, that is highly unlikely.

This is really exciting, because it opens the posibility that Gambusias could potentially be used as a vector species to transfer genes between swordtails and guppies (fancy showa koi guppies, anyone?) On the other hand, bad news for the purists (sorry, guys). I'll just have to wait and see if any of these little fellas survive to maturity and are not sterile.


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## emc7

Yeah, I guess I'd rather see you maintaining nearly extinct species. But this is pretty interesting. And your best bet to make money in fish if to be the only breeder of something new. Those koi guppies could pay for all the experimentation.


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## PaulLamb

I got a somewhat better picture of one where you can see the orange pigmentation. He looks kind of blue in this shot, but he's more greyish in reality:


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## TheOldSalt

Oh good, you finally for some concrete results. I was a bit worried for awhile that you wouldn't. I'm not sure why you're having so much trouble getting a guppy/Gambusia cross, but I'm sure that you will eventually.

Hmmm.. transfer vectors for genes. Nifty idea. If you ever do invent a koi guppy you'll make some serious bucks.

Swords are renowned got their hybridization capability, and many of the resulting fish are fertile, so I'd say there is a good chance of your new fry being useful.


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## PaulLamb

I thought I would post an update on the affinis/swordtail hybrids. Another one of them died, but the remaining two are doing well. There coloration is faded compared to pure swordtails, but remarkably vibrant compared to pure affinis, and the koi pattern is perfect. They also have a lot of blue-green pigmentation in them in the "white" segments (no idea where that came from - neither parents have this type of color pattern).

My favorite one (I call him hybrid C) is growing at a surprising rate (huge for a 3-month old). He is much larger than the other, and has even begun to develop a gonopodium. He has no sword, and his body-shape is a bit odd. The width of his tail segment is much thicker than a gambusia's, but thinner than that of a normal swordtail. His dorsal fin is rather sail-like, unlike a gambusia dorsal fin, but not as long or wide as that of a swordtail. His mouth is also shaped in-between the two. He is really a nice mix of the two - more elegant and streamlined than a normal swordtail. Here are a couple of nice pictures of him:
















The other one, (I call it hybrid A) is shaped quite differently (probably closer to affinis), and its colors are more vibrant than hybrid C. Most notably, its headline is much less angled than that of a swordtail, and its dorsal fin is smaller. This guy's smaller size is more what I would expect for a juvenile at this age. It hasn't matured as much as the other, but I suspect it is also going to be a male (not positive yet).









Here is a shot of them together, for size comparison:









And next to an adult swordtail for comparison:


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## KevinP

Wow those look amazing. I would never expect that you could get a Gambusia Affinis cross to look like that. I will be watching this thread with interest.


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## PaulLamb

I've had more bad luck with the Gambusia/guppy hybridization. The one pregnant female I had died before giving birth, and I've not had any subsequent female guppies survive long enough to get pregnant. I'll keep trying, but I'm not very hopeful at this point - Gambusias are just too aggressive toward guppies. The male swordtail + female gambusia is a considerable easier combination, and should work fine for my aggression-gene counting experiment. I've started trying for more of these hybrids in case the two I have are sterile. Hybrid C is probably mature enough to start trying to cross him back to a pure swordtail female (I have some juvenile swordtails that I separated as fry, which I plan to use when I can positively identify which ones are females).


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## PaulLamb

KevinP said:


> I would never expect that you could get a Gambusia Affinis cross to look like that.


I am more than a little amazed myself. I expected the orange pigmentation to be a codominant trait and show through on the first generation, and I was correct about that. However the "koi" pattern showing first generation is a real surprise. I don't know a lot about swordtail genetics, but in most species the color white is a recessive trait. In this case, the bicolor pattern seems to be dominant, while the "affinis grey" shows through where white would normally be present, along with an odd blue-green pigmentation. Strange things do seem to occur when playing with hybridization.


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## PaulLamb

All of the swordtail-affinis hybrids I've produced so far have been sterile, which has thus far prevented me from determining the number of genes linked to aggression. They are nice looking fish, but not very useful due to their low survival and high mortality rates, proneness to cancer, high aggressiveness, and sterility. Additionally, I have also had zero luck producing an affinis-guppy hybrid (to be more specific, I have been unable to get a female guppy to survive the breeding process long enough to get pregnant, then recover and actually give birth). In the interest of saving space and being more productive, I've decided to abandon the idea of counting the aggression genes using hybrids, and instead focus all my energy and aquarium-space on selective breeding of pure affinis and holbrooki lines for less aggressive behavior.


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## TheOldSalt

Oh, darn; things were really looking good for awhile there. Well, maybe you'll have better luck with this new approach.
( hmmm... you think you could maybe invent some sort of breeding harness to hold a female affinis so a male guppy could fertilize her and then escape with his life? )


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## PaulLamb

Haha, I don't know if I'm creative enough to engineer something like that. One thing I haven't tried is to put a single female gambusia into an aquarium loaded with male guppies - one of them might get lucky (I have this vision of a total guppy massacre). It might be worth a shot though. I think ultimately it's just a numbers game - keep trying the male gambusia/ female guppy combination until it eventually works. I'm just not sure how useful the information is. It would be interesting to know how many genes I'm working with, but I've been at it for over a year now, and I'm starting to wonder if it is worth the effort just to satisfy my curiosity - I'm using up a lot of aquarium space for it. In the end, knowing the number of aggression genes is probably not going to change the selective breeding process anyway. It is far more useful for me to find out if aggression is something that can be bred out of the gambusia, because if not I'll need to go a different route for my ultimate goal (in other words, it won't be possible to produce a "fancy gambusia" if they kill everything colorful with long fins).

(edit) I gave the "harness" idea some more thought, and remembered something I did once as a kid - put a "leash" on a fly using sewing thread and a drop of superglue. Playing around I've found that I can get superglue to stick to a fish if I rub the slime off a small area with dry tissue paper first. I've attached short strings to the head and abdomin of a couple of my gambusia females, and put them back in the aquarium to see if they develop problems from the glue and how long it can hold for. I'm not sure if something like this will work (I can imagine her struggling and causing injury if I use this to somehow try and hold her in place, but I'll see if I can come up with something workable)


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## TheOldSalt

Hahaha! Awesome! If it actually works, you'll have no problem getting the story published.


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## Big Business

Very interesting experiment!!! I was actually thinking about trying to hybridize a gambusia with another live bearer to create a "fancy" gambusia, so I googled it, and came across this thread. Your posts convinced me to sign up for the thread. Very cool stuff.


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## PaulLamb

Nice to see there are folks interested in this. I'm convinced that the gambusia/guppy combination offers the best chance of a non-sterile hybrid strain, but I would be really excited if someone else was to produce one with any type of live bearer. (I'd pay quite a bit for some first-generation proven non-sterile hybrids).


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## funlad3

I kept ignoring this thread thinking that a Gambusia was some type of plant. I really need to stop doing that! AWESOME thread and extremely interesting. I wish you the best of luck. Also, for the guppy gambusia hybrids, instead of putting a bunch of flashy males in with a gambusia female, put one gambusia male in with a bunch of guppy females! It will increase the chances of one of them surviving, and who knows... Maybe he'll be less aggressive with a large amount of females. :razz:


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## PaulLamb

Thanks for the suggestion. I have tried a low gambusia male to high guppy female ratio, without luck, as they seem to pursue (and eventually kill) them one at a time. They do something similar if you put one male with a bunch of female gambusias - he will tend focus all his attention on his favorite one and ignore the others. However it might be worth another shot, maybe with only female endlers which seem not to be as fun for them to kill as the regular guppies. I'll probably get rid of my swordtails and focus the extra aquarium space on guppies.


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## funlad3

Oh... At least you've tried everything! Maybe your fish leash will work! Good luck!


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## iheartfish:)

This thread is extremely interesting, I can't wait for the next post! Wow, who would've thought that I'd be so exited about a thread?


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## PaulLamb

The project is a bit on hold, since I'm on a TDY and won't be back home until September. My wife is caring for the fish back home, but isn't too keen on the weird fish experiments  I'm reduced to a small 10-gallon aquarium and a dozen affinis in the mean time. The glued strings do stay put though and don't seem to cause any permanent damage, so at least that's one experiment I can play around with.


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## funlad3

That's awesome... :fun:


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## TheOldSalt

HAHAHAHAHAA
This is gonna be one for the books.


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## Big Business

Someone else is trying a similar experiment in a different forum:
http://www.aquariacentral.com/forum...-im-trying-a-hybrid&highlight=gambusia+hybrid


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## iheartfish:)

damn copycats! 

ummm... What's a tdy?


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## emc7

I saw something about a limia perugiae gambusia hybrid attempt, but i can't find it again.


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## TheOldSalt

When military servicemen are sent someplace for a short time, usually for some specific reason, it's called Temporary Duty, and that is shortened to tdy.


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## PaulLamb

TheOldSalt said:


> When military servicemen are sent someplace for a short time, usually for some specific reason, it's called Temporary Duty, and that is shortened to tdy.


What he said.


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## iheartfish:)

Oohhh.....


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## Big Business

Any progress, Paul?


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## PaulLamb

I haven't done too much since my last post, since the project is on hold until I get back in September. I only have one aquarium here so my experiments are fairly limited. The superglue harness experiment had to be halted, because the other tankmates peck at and eventually kill any female who has strings glued to her.


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## pj1218

wow great job  i remember reading this tread when there was only 2 pages and now seeing how far you have come is amazing! and the thought of the fish leash made me laugh soo hard  good luck


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## iheartfish:)

Well, it's october!!!!  Still waiting patiently for updates


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## PaulLamb

Sorry for dropping off the radar for a couple years. A series of life events, downsizing, and financial troubles forced my wife and me to abandon the project for a while and sell the holbrooki stocks, aquariums, and equipment. It wasn't a complete loss though because we learned a lot, and we have had time to think about and discuss plans for the project once we could pick it back up.

Things have finally started settling down again, and I've begun collecting the necessary equipment again. It will be a while before we can get back to the level we were at before, but I have already netted some wild affinis from Kansas where I got my previous stock. We are no longer living in Maryland, so I probably won't be able to replenish the wild affinis/holbrooki stocks, but I have netted some wild affinis from a lake here in Texas, so I'll have a genetically diverse stock to work with. I've treated the fish for parasites, and I'm observing them for defects. At some point we'll also order new native Florida holbrooki from the breeder we bought them from before (want to be better set up first).


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## mousey

I had wondered where you were!!


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## PaulLamb

Thought I'd post a small update for anyone following this thread. Since my last post, I netted some more affinis from a park here in Texas, some from a stream in California, and some from a different lake in Kansas.

In case anyone is wondering why these three states, we currently live in Texas, my wife's family lives in California, and my family lives in Kansas (I like catching fish when we go to visit our folks). I currently have the Texas, California, and Kansas groups separated for observation. The parasite treatment regiment is complete, and I am in the process of weeding out the least healthy looking individuals over the next few weeks until I have chosen a good foundation stock from all three groups.

I haven't finished writing the lineage tracking website yet, so in the mean time I thought I would post a few photos to keep the thread interesting (I haven't had a chance to build another observation table yet for taking nice photos and videos, so these are just some random pics taken from my phone).

I took these first two in Kansas on our way back from our California trip. First three jars are the fish I caught in California, and the second three jars are the fish I caught in Kansas:




















And these are the three groups back home (first pic are the fish from California, second pic are the fish from Kansas, and third pic are the fish from Texas):




























I've not done any aggression measurements on these fish yet.


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## mousey

Are they not fighting amongst themselves?


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## PaulLamb

Only the normal pecking rank and females snapping at the males who get too amorous. I am feeding them three times a day, so none of the more serious hunger agression. Also, there aren't any large near-term pregnant females in the mix, so no wildcards. Main issue is with other species anyway (they are robust enough to handle each other)


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## PaulLamb

One of the things I am doing differently this time around, is that I am no longer constructing the large, custom breeding tanks. The original design consisted of four main sections, with two subsections and a birthing chamber each. This design was overly complex (especially with the filtering system), didn't utilize space very efficiently, and was also quite expensive to construct. I can acomplish the same goal with cheap 10-gallon aquariums divided into two sections, each with two commercial dual-chamber floating livebearer breeding boxes.

I put together a diagram for how my line-breeding strategy of four lines and two rotations could be done with just two 10-gallon aquariums set up like this (leaving a lot more room for additional aquariums to separate fish as necessary). I used some color highlighting to make it easy to distinguish between generations (and obviously this isn't intended to be drawn to scale)


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## PaulLamb

Why gambusias are not good community fish


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## PaulLamb

Thought I would post a progress update. I've run into a couple of problems that could mean I need to think up a new strategy.

The first problem is with how I am housing the individuals. Through most of the breeding cycle, every fish is confined to a chamber in the breeding box. This results in a higher overall mortality rate, which has an impact on genetic diversity (which was the main benefit for using this method initially, as I could control which specific pairs are breeding). The problem is, when an individual dies, his/ her intended partner must be bred with an individual from their own rotation (who is unfortunately also their sibling). There have even been two instances where both potential breeding partners died, resulting in the loss of a breeding line, requiring stock to be pulled from a neighboring line, which further reduces genetic diversity. I'm not sure how to resolve this particular problem, other than to use a different setup that requires more room (such as my custom breeding tanks that I was using before), or just accepting the risk of working with a narrow gene pool (impacting the robustness of any future developed breeds)

The second problem is that I have been using neoteny as the focus of my selection strategy (choosing individuals which exhibit aggressive tendencies later and later in their development). This unfortunately has the unintended side effect of choosing individuals who have health problems (they may be less aggressive because they are sick, not because of their genetics). This also contibutes to a higher mortality rate, and further reducing genetic diversity. The solution for this problem is to keep more individuals from each brood, and do a second selection among them based on health condition when they are older. This of course will also take more room and equipment.

I'll post another update when I get the kinks worked out of the process and things are running more smoothly.


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## TheOldSalt

Oy! Well, having all these problems is a drag, but at least you see some solutions. Good luck!


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## PaulLamb

Oh, forgot to mention, I have finally had luck with guppy/ gambusia hybrids. The combination that worked was a Gambusia Vittata male with a large female fancy guppy. I'll post pictures of the fry when they are larger. There are at least five of them (still tiny and hiding in the plants, so don't have an exact count)

The Vittata are a variety I recently purchased online, originally to try and bring more genetic diversity along with some color (or at least variety of patterning) into my breeding lines. They are also less aggressive than Affinis, which is a bonus for this project.

The Vittata are a more tropical variety of Gambusia with lower tollerances, which makes them less useful for my other project, but they could make a nice vector for more easily bringing in new color genes from guppies (assuming the hybrids are not sterile). They seem to be more easily crossed with guppies (or I might have just gotten lucky )


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## TheOldSalt

Cool! Maybe these hybrids will be easier to cross with the coldwater G.affinis.


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## Big Business

PaulLamb said:


> Oh, forgot to mention, I have finally had luck with guppy/ gambusia hybrids. The combination that worked was a Gambusia Vittata male with a large female fancy guppy. I'll post pictures of the fry when they are larger. There are at least five of them (still tiny and hiding in the plants, so don't have an exact count)
> 
> The Vittata are a variety I recently purchased online, originally to try and bring more genetic diversity along with some color (or at least variety of patterning) into my breeding lines. They are also less aggressive than Affinis, which is a bonus for this project.
> 
> The Vittata are a more tropical variety of Gambusia with lower tollerances, which makes them less useful for my other project, but they could make a nice vector for more easily bringing in new color genes from guppies (assuming the hybrids are not sterile). They seem to be more easily crossed with guppies (or I might have just gotten lucky )


Very cool! Please post some images if the hybrids are still alive. :shock:


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## mousey

sounds interesting. Hope the fry grow ok. looking forward to pics.


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## thedragonslayer

Love this thread. Read it from beginning to end. I recently got back into guppies and my 3 females popped out 74 fry. I do not know if gambusia normally have large amounts of fry as guppy do, but wondered if you had ever tried putting same age fry from both guppies and gambusia together and raise them together before colors developed to see if it would make a difference. I will be coming back to this thread to see your results.


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