" wrote in
ups.com:

It has a torn up tail, the main fin is slightly torn. It still eats. Is
there a problem with it? I have a twenty gallon tank with five cichlids
in it. Could they be fighting as well?

Cichlids are notorious for aggression, a damaged caudal fin is a sure sign
of it.

What sort of cichlids do you keep? 20 gallons can be small for Africans or
Central Americans depending on the size and species. If cichlids are
unable to avoid aggression by fleeing or hiding it will eventually lead to
stress, injury, and death.

I suggest you try using Melafix to help speed the healing unless the injury
looks heavily infected. Some signs of infection can be redness,
inflammation, excessive slime shed, stringy white material, or sharp
bristle-like hairs. If the aggression continues no medication will be of
much help.