I have been in the tropical fish hobby for many years and have never seen anything like this before. I think it is a very aggressive type of fungal infection. My fish were fine in the morning. I check them carefully every morning when I feed them. There was absolutely no sign of disease at all. The water quality in my tank is perfect. I know how to care for, treat, and recognize disease. When I got home from work 8 hours later their fins were rotting away and there were sheets of thin white slime just coming off their entire body and you could see it clearly all over the bodies and eyes. I immediately treated them for fungus, but the disease was so aggressive that they were all dead a few hours later. Because I am so experienced I am stumped and would like to know what happened.

I would say it was a water quality issue. Perhaps a massive ammonia spike which stressed the fish and caused them to produce massive amounts of excess mucous. High ammonia levels would also damage the fins and tail and cause the eyes to go cloudy.

Fungus only gets into a damaged part of the body. It rarely affects more than one or two fish at a time and takes several days to kill the fish.

Bacterial infections turn up as red patching on the body or fins and even the worst bacterial infection takes 24 hours to kill a fish.

There is a strain of whitspot that I had in my tanks that killed within 24hours of noticing it. The fish would look fine but half a day later were covered in fine white dots and appeared to be covered in excess mucous. Then the next day they were all dead. But you could actually see little white spots.