IDK Whats Going On

[Waffen06]

Hi everyone, hope I can get some help. Ive been keeping fish for 15 years (fresh and salt) and never had an issue like this before. My wife has a 54 gallon aquarium that has been set up for about 4 years. Not many fish were kept in it and it had the same inhabitants for the past year (3 albino cory cats, a neon tetra and a couple serpae tetras). About 4 weeks ago the last neon passed and we decided to add a few new fish. We added a small pleco, a small blue gourami, a pictus catfish and an angelfish. After a week everyone was doing well but awoke to a dead pictus. Returned him and got another. At this time I decided to move the tank (only over a couple feet) drained about 75% of the water to move it and refilled. Fish got really stressed but were fine the next day. 2 weeks ago we added a 2nd angelfish and 2 mollies. All were doing well and eating. Then on friday awoke to the last of the tetras dead, didnt think much of it as weve had them for over 2 years then it went downhill. Saturday the pictus, an angel and a molly were all dead. I tested the water and everything looked good, 0 ammonia, 0 nitrites, about 15 on nitrates, PH of 7. Monday morning the other molly and a cory cat passed. The last angelfish looks terrible, pale redish spot on its side and looks like its peeling. The gourami, pleco and 2 last cory cats look okay and are acting normal. Im at a loss

 

[danny291]

maybe it was an ammonia spike

 

[libertybelle]

How old are your test kits. Are you using a liquid ammonia kit?

Even if ammonia didn’t cause the problem i think it’s a bit suspect that you have zero ammonia in a tank that has had that many dead fish in it for some hours.