And I have no idea why. There is no amonia, nitrites, the nitrate level has not risen above 10, in fact it's usually at 0, the temp stays around 80, I change 30% of the water every 2 weeks, all my fish are docile and appropriate to the temp, the ph is stable at 7.6, all the fish that have died I have had for a while and I have not added any recently. I lost 4 plattys and a catfish and my white skirt tetras are not looking very good. I also can't quite figure out what's wrong with them, they just die. The only thing I can see is one of my white skirts looks like his right gill is swollen. I'm really at a loss! :help: