Today my 3 Leporinus in my 125 community tank died within hours of a 30% water change and I have no idea why, definitely bummed out. Prior to the water change which I do about every 12 to 14 days the water parameters were normal, maybe about .05 ammonia and all else normal. I have no idea what happened as they have been through several water changes like this one before and every other fish, loach, and snail in the tank are fine. The water temperature never varied more than about 1.5 degrees, I use a laser thermometer for the tap water. After each water change I add prime and Pristine as directed and a little carbon(flourish) for the plants. I tested the water after a few hours, ammonia at 0, nitrates around 30, all others the same as always, any ideas? I really liked these 3 fish and now I am afraid to get more.