# Sticky  How to identify male from female...



## ronnfive

*How to identify male from female:*

*Swordtail* (Xiphophorus helleri) – this type of livebearers are easily sexed through observation. The male Swordtails have swords on their tails while the females do not. Usually the female is larger and has a rounded body than the male. Generally, the best observations are focused on their “gonopodium” or what we called the modified anal fin. It is a tube-like fin at the lower backside next to the belly of the fish.

*Guppy and Endler* (Poecilia reticulata/Poecilia sp. endler's) – this type of livebearers are easily sexed through observation. The male Guppies or Endlers are smaller and more colorful than the females. Generally, the best observations are focused on their “gonopodium” or what we called the modified anal fin. It is a tube-like fin at the lower backside next to the belly of the fish.

*Molly* (poecilia latipinna) – this type of livebearers need more observation than the other livebearers. The common male Mollies have a colorful tail (like bluish or greenish color) having a larger dorsal fin, and is usually thinner (viewed from top) than the females. Generally, the best observations are focused on their “gonopodium” or what we called the modified anal fin. It is a tube-like fin at the lower backside next to the belly of the fish.

*Platy* (xiphophorus maculatus) – this type of livebearers needs careful observation than the other livebearers. The male Platies are typically smaller or thinner than the females. Generally, the best observations are focused on their “gonopodium” or what we called the modified anal fin. It is a tube-like fin at the lower backside next to the belly of the fish.

Here is the male’s gonopodium 

A closer look…
Gonopodium

Here’s a female 
Anal fin

A closer look...
Anal Fin

Hope you find this useful...
Ronn

Please feel free to correct me, if I’m wrong or add something... so that this will be very useful to the others or new into fish keeping of this type of fish. Thank you.


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## Lydia

Good info! Maybe this should be made a sticky or put in the articles section?


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## TheOldSalt

Done!
We get this question so much it's high time we had a sticky for it.


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## ronnfive

Thanks much! Hope this will help a lot of people who's into this type of fish. This is a great fish and very hardy. 

ronn


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## apple

http://public.fotki.com/apple1/fish/ is my gold molly in the breeding nest a female lol i hope i didnt pu tthe wrong fish in the breeding nest lol


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## tonkstoy2003

Okay with the swordtails, only the Males have the sword? because I can sex the fish, but the lps told me that the two i have the one with the sword was the male and the one w/o it was the female, what puzzles me about this is the fins on the bottom are the same in both. they both have the same fins underneath just like my mollies. That's what i was confused about  Thanks


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## ronnfive

Pic would help a lot... 

All livebearer fish born females, then later on when they are old enough or about 2 months old or so, some of them decide to change gender and some continue being females. One of these situations is that sometimes this type of fish decides so late… and later on shows gonopodium and in your case swords. A late bloomer fish, what we called it…mostly they grow quite large that they looked often mistaken as female. I hope this help!

-ronn
ronn.gfxartist.com


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## Steve155

This is great! Thanks!


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## tikotaz

*Helpful, though confusing*

I have a male and female creamsicle molly they have similar dorsal fins though the one in a seperate tank is smaller. But underneathh it's hard to tell, they look similar as well and I can't up and squint to see if the one in the seperate tank has that part, though belly is getting bigger each day. Was told that it was a female, yet still not birthing yet.


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## cocomania

Great job, I will deffinently keep all of this in mind when i start buying all of my fish.


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## elvis332

* RONNFIVE YOU ARE RIGHT I HAVE A SORDTALE AND THE MALE HAS A BLACH SKINNY LINE IN ITS TALE*


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## vettech909

great info!!!now i know i have 2 females and 1 male
:fish::fish::fish:


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## audzter

Nice info!!!


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## Manthalynn

*She's now a he!*

Scientifically speaking, what causes them to decide to become male or female?

Is it physiological, ecological, or environmental (those last two might be the same...)? I'm curious about the cause because this happened (I think) in my 10 gal tank. Maybe "s"he is just a late bloomer.

I purchased a male and female swordtail about a month ago. I can definitely tell the difference between male and female livebearers but I think I was distracted by the one having a long tail and the other having a short, blunt tail. The more I looked at it I thought, now that's confusing, that looks like what I would expect to see on a male.

Tonight after moving a lot of things around, I just noticed that the "female" is starting to get an extended tail! That clears up my gender confusion, I guess.

To aid with the discussion, I have waaaay too many other livebearers in this tank so I wonder if it's a sort of darwinian pressure exerted from the others. Although I always thought it was the males supressing the other males from developing.


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## ThatFishKid

I noticed to my dismay that a group of livebearers was left out: Halfbeaks! I can't seem to determine weather or not there is a "modified anal fin" on the males or not. Size difference is the only thing i know of.


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## Guest

Manthalynn, more than likely your fish is a "late bloomer". Male swordtails often develop secondary sex characteristics slowly. Some older females, however, aren't incapable of switching their sex after becoming infertile.


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## Buggy

Wish we could do that. lol


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## Manthalynn

Leah, thanks for the information!


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## OldMan

Simple contrast may help with identifying the genders of common livebearers, not all of them. 
This is a male with the gonopodium on him. It can be easily seen starting just behind his belly and extending halfway to his tail. 









This is a female. The triangular fin is located in the same place as the gonopodium on the male but in this fish it reminds me of a fly's wing. 









Both of these are Heterandria formosa in which the gonopodium is a bit bigger relative to the body size than many common livebearing fish. Both fish in the pictures are adults but only about 3/4 inch long. Blowing them up to make things easily visible has made the pictures a bit blurry.


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## Manthalynn

OldMan, thanks for the photos. I've since figured out the difference, but when I was just starting out, it would have been nice to have contrasting photos in the actual thread.

Question for you: I had a batch of mollie fry on 11/8. I am pretty sure one of them is definitely male. Do they really develop this early? They're about 1/3 to 1/2 the size of the adults, but this one in particular, I'm pretty sure it's a he.


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## barty boy

hi ppl jus wondering if any 1 can help
i know this sounds daft but can mollies change sex because i have a large orange molly wich im sure is female but its underfin is gettin rathe long an starting 2 resemble a male but it has 2 fins further 4ward where my male hasnt 
plz help cheers


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## Guest

that would happen in two instances:

1: its a late bloomin male.

2: its a really old female.

am more inclined to option 2.


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## jaunypic

I have 4 white mollies. anyidea to tell the diference hear?


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## guppybreader

yes it is so odvious


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## whitemore55

Well done!!!

I think you have a lot of interest about male and female. Just joking....

You have noticed it very near and clearly. For this you can recognize it.

Thank you for sharing....


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