ich probably. i think u can only treat the fish when those the ich protozoa reproduces and get out of the fish. i don't know any treatment except salt bathing. i think if one fish caught ich, the whole tank catches it, so better remove it. if the other fish show symptoms like white spots and flashing, the whole tank is infected. i feel really sorry for u. when my tank got ich, it killed many. it might not be ich though. i am no expert.