Sudden death of one of my fry

[chaoslite]

I had a small batch of 8 four week old fry that I had to move to a different tank # days ago because the parents decided to breed again. Today I fed GP and about 20 minutes later one of the fry began to swim at the top of the water. After about a minute he started to list to one side and then shake. That lasted about a minute before he had a hard convulsion and then fell to the bottom of the tank dead. I immediately did a 90% water change. Anyone have any ideas?

I didn't think to do a test on the water before changing it.

Right now the water parameters are:
ph 7.4
ammonia 0
nitrites 0
nitrates 0

The other 7 seem fine and are eating. I normally do a 50% water change twice daily making sure to scrub down the tank. The only thing that would be different in my water change would be that I am trying to slowly increase tap water to my water changes. The fry grew up in RO water which I had slowly begun to add tap water to, before the parents decided to spawn again.

Mishka

[mmorris]

Bummer, I know. How many days ago did you move the fry? Did you add a cycled filter to the baby tank? What temperature are you keeping them at? Are you ageing your water? Is the incoming water exactly the same temp and ph as the outgoing water? You should not have 0 nitrates. It suggests that the baby tank isn't cycled.

[chaoslite]

Bummer, I know. How many days ago did you move the fry? Did you add a cycled filter to the baby tank? What temperature are you keeping them at? Are you ageing your water? Is the incoming water exactly the same temp and ph as the outgoing water? You should not have 0 nitrates. It suggests that the baby tank isn't cycled.

I moved the fry 4 days ago and used water and a cycled sponge from the breeding tank which had been running for over two months. The water is aged a day even though it stays the same ph. The temp of my tank is 84 degrees and the temp is the same when I put new water in. Any advice would be appreciated.

The remaining fry are all swimming around and eating like pigs.

Mishka

[mmorris]

It sounds like you did everything right, Mishka. It might be 'just one of those things'...food lodged somewhere in his body, a freak gas bubble, who knows? They are so delicate at this age.

[kaceyo]

When these things happen you'll usually never know what caused it. The best you can do is look for possible reasons so more fish aren't effected if it's something you can find.