# Wonder why they died?



## MrsBee93 (Aug 12, 2008)

My 10gal fish tank is almost 3 weeks old. It is fully cycled:

Nitrites are finally at 0 (they had spiked at 5.0 for a couple days and slowly dropped, thankfully)

Nitrates are at 0-10 (hard to tell on the dipstick chart)

Ammonia is 0.

Hardness, pH and alkalinity are all naturally high. I bought our fish from our LFS, so the fish are acclimated to these conditions.

Okay, I bought 2 dawn platies at the very beginning of the process... both did very well all through the poor water conditions. (I did frequent water changes, added a little salt, treated the new water with Stress Coat, watched the amount of food I fed.) But today, one of the platies died.

Why? The water is finally good and I thought they were safe now. They managed to get through the worst conditions, so why did he die?

Another question... the surviving dawn platy is plump, with nice shape. The one that died was skinny with almost no shape. Did he starve? I assumed that I must have gotten a male/female pair, but now I'm not sure. 

TIA!


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## Sea-Agg2009 (Aug 2, 2008)

Well, stress usually doesn't kill something right away. It kinda builds up over time. Also the fact that the water wasn't "right" at the beginning may not be as such a big deal as that the water condition is constantly changing. That changing water condition can stress the fish out as well. Of course, I would not say for sure stress killed the fish. 
As for the size of the fish, I'm not sure. Would you say plump as in "well fed", or plump as in fat? Either way, that fish seems pretty healthy. Overall, I would wait a week before getting any new fish. Make sure this one is doing good, and then go from there. Get 2 more, or some small number, and make sure they do well in the tank. If the new fish and the current living fish keep doing fine, just call the first loss a fluke and move on from there.


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## emc7 (Jul 23, 2005)

Just because a fish survives a cycle doesn't mean it didn't take damage. Ammonia burn on gills is like pneumonia in people, you get better, but can still have trouble breathing and be more likely to die from the next infection to go around. And even if the fish didn't suffer in your cycle, you don't know what it went through in shipping to get to you. 

3 weeks wouldn't be long enough to declare a new fish out of quarantine, so it could have died from something it came in with. A sunken/concave belly could mean internal parasites. 
Its really rare for a healthy fish to starve, but it can happen if a parasite is stealing its food. 

Male swordtails have a pointy anal fin (the one on the bottom rear of the fish), females have a rounded triangle. 

And there are also random fish deaths. They have accidents (hit their head on the lid), natural causes (heart attacks, childbirth), or even kill each other (usually you see signs of this).

Unfortunately, one death doesn't tell you much. Wait a few weeks to make sure the other one doesn't sicken, and then pick out a new fish. I'm sure you don't have another tank to quarantine any new comers, so your survivor will have to take her chances with what a new tankmate brings. 

Alternatively, if she is really fat and looks square from behind, maybe you just want to wait. She may populate your tank all by herself.


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## Sock Yee (Dec 29, 2007)

You might want to take into consideration that the fish could have been unhealthy when you purchased it. Usually transportation and the waiting period in the LFS could have taken its tool on the fish. It might have caught illness at the shop and so happen that it doesn’t show the symptoms until you bought it. I’m sorry, but sometimes these things happen.


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