I had 11 balloon moly fry in a 12-gallon tank. Five of the fry were about 3-months old, and the other six are about 2-months old. They've been living in this tank for almost two months. Last night I did a 10% water change (which I usually do three times a week) and all of the fish seemed fine. This morning I found two of the 3-month-old fry dead. I bought a water test kit which said that my ammonia, nitrate, nitrite, and chlorine levels were all 0 and the ph was 7.0. I have not changed water conditioners or food recently. I'm careful not to overfeed the fish, who receive three small meals a day.
The two fry that died were the largest of their litter, and I would have guessed they were the healthiest. They did not appear to have any diseases or to have been fighting. The rest of my fish still seem fine. The only thing that I can think of that might have caused their death is that the plastic on my heater was peeling a little bit. I'd never seen any of the fish pick at the heater, so even this doesn't seem likely to cause two fish to die (although I've already replaced it with a new heater). I'd appreciate any help or advice about what might have gone wrong, because right now I have no idea but I do not want any more of my fish to die.
The two fry that died were the largest of their litter, and I would have guessed they were the healthiest. They did not appear to have any diseases or to have been fighting. The rest of my fish still seem fine. The only thing that I can think of that might have caused their death is that the plastic on my heater was peeling a little bit. I'd never seen any of the fish pick at the heater, so even this doesn't seem likely to cause two fish to die (although I've already replaced it with a new heater). I'd appreciate any help or advice about what might have gone wrong, because right now I have no idea but I do not want any more of my fish to die.
