I have 3 zebra danios in my 20 gallon tank and they were perfectly fine along with the other fish and then over then course of about an hour one of them just started to have trouble swimming and staying balanced in the water and seems kind of tail-heavy. the only thing i can think of is that it's because i just bought a new kind of food (tetra color crisps). It will flash and dart in a downward spiral often getting stuck in between two plants and then just staying there as if it's dead.
The water parameteres are fine i just checked them last night.
I have put it into a tupperware container with some of the tank water and it has stopped flashing and is acting somewhat normal but i sometimes catch it lying on it's side on the bottom for a few seconds. I was thinking of maybe trying to feed it a pea later tonight because it wouldn't eat the last time i fed the fish. I don't see any signs of
ICH or any other diseases