I have a 55 gallon. It has a 2 male victorians and 3 female.One 4" dempsey (friendly) some baby vic./zebras. which the demsey hasnt ate for some reason. I just added a 7" blue dolphin. He isnt doing well. head went dark. not active. Water peramators are good. Ph is high 8.3 nitrate a little high just added stress ease and the not natrual amonia detoxer. If that dont help I guess ill change more water. Any suggestions???