My old tank boss, an OB peacock, changed his behavior about a month ago. For a little background, He is about 2 years old, 5" long and lives in an all male peacock 4' long tank. He quit swimming among the other fish and stays inside his cave at the bottom of the tank, but he use to be all over the tank just a couple months ago. Now he only comes out once a day to feed in the morning. He doesn't eat during the second feeding in the evening, but he use to be one of the most aggressive eaters. His color isn't as bright anymore either. The water levels are good for nitrates, nitrites, ect… No new fish have been introduced lately. I'm trying to figure out if this is just behavioral or an illness. A couple months ago I did notice an odd behavior a few times where it looked liked my rainbow shark was cleaning the OB. The shark is smaller and stays out of the Cichlids way generally so if the OB didn't want him doing it, the OB could have chased him off. Could this be a sign of a possible parasite? No physical symptoms have shown besides his color being worse. Any thoughts? Would it hurt to treat the whole tank with salt just in case?