I brought home a sick fish from petsmart the other day who passed with in a few days. He was twitching uncontrollably for a few hours then died. I decided to not replace him and just stick with my 3 boys. Well today I did a water change and now my most active boy is laying on the bottom and will not eat. I used separate water change supplies from the sick fish so I do not believe he could've caught anything from him. But nothing appears to be physically wrong with him besides that he is laying on the bottom and a little clamped up. I don't think it has anything to do with why he's on the bottom but this past week he's begun fin biting. I don't know whats happening to my fish lately but they seem to be dropping like flies!