I worry my fish may be sickI had an small Algae Eater in, but he diedSo, I wonder if he was sick, and if so, could my fish have caught something.They swim, eat, and are very livelyBut I notice 1 has a red spot on his headIs that a illness in Goldfish? Or could it just be some kind of bumpThey swim fast alot, and sometimes knock over things in the tank, and get crazy when you first tern the light on them.So, could it be a bruise, or are red spots/bumps a bad sign in goldfish?Your algae eater died because you didn\'t feed itThey can not survive on algae growing in a tank, and no fish will eat other fish wasteYour aquarium is probably too small and the high concentrations of ammonia is causing chemical burns on your fish The first gold fish needs 20 gallons, every goldfish after than needs another 10 Algae eaters are tropical fish, gold fish are cold waterThey are incompatible and this could have also lead to fish deaths.Other related question