What is the symptoms and treatment coccidiosis in fish?

There are very few species of fish that can actually be troubled by this problem, and the possibility of your fish contracting one of the bugs that cause coccidiOSis is minute. If you say what species of fish you have I can advise you if it is even possible for that species to be infected. It's far better you look after your fishes water quality than waste your time worrying about such an unlikely problem as coccidiOSis. The basic rules for successful fishkeeping are :- 1 inch of fish needs at least 1 gallon of water. :- Every tank needs a permanently running cycled filter. :- Every tank needs to have 50% of its water replaced every week. The aforementioned are absolute necessities if you wish to keep fish alive for any length of time. I can guarantee that if you fail to keep any of the above basics, your fish will constantly be getting sick, and they will have shortened life spans.