So here's a little history. I bought the Danio's as cycling fish, yes i know i shouldn't have but i was a complete noob at that time. that was back in January. They all survived the cycling process. and a few months after it was fully cycled They've been slowly dying off one by one. It's weird but one will get sick, go to the top left corner of the tank and just stay there until it dies. At the start it will sometimes come out to eat, but after a few days it stops eating. Once that one dies, then the next one starts the same process, never 2 at a time. It's really weird. Parameters are all spot on, the tank is not over stocked at all. There is plenty of filtration and airstones and plants. None of the other fish show ANY signs of anything bad. Just the Danios. I do regular water changes and everything correctly. There are no white spots, no fin rot, no curved spine(except for 1). Nothing, it's like they see one do it and when he dies they want to try it.