Convict cichlid with problems

[byron]

I recently bought a convict cichlid about 3 inches long, little did I know, I purchased a fish with problems. The convict has an organ type thing sticking out of its anus(pooing hole) (or wutever it is called, not quite sure lol) Anyways this fish is eating well but it cant really float in the water. It tries really hard to swim up top and when he stops moving its fins, it immediately sinks back down to the problem. I felt really bad and If i returned it back to the store, I know the fish is gonna also end up unwanted. Right now I dont really know what to do with the convict and What problem does it have.

[BaoBeiZhu]

your best choice is to sell it to a monster fish keeper