yeah naturally it would attack an oscar or any other fish tossed in there because they're terroritorial. i'd consider that more a natural reaction then a sign of being aggressive.
how big is it? if it's too big for bloodworm i wouldn't bother. a feeder here and there is fine IMO, just quarantine first. if it were me, i'd check the water params like JP asked earlier, make sure everything tests out right, give it a couple of feeders and then start the process of fasting it onto talipia, smelts, pellets etc etc.
how big is it? if it's too big for bloodworm i wouldn't bother. a feeder here and there is fine IMO, just quarantine first. if it were me, i'd check the water params like JP asked earlier, make sure everything tests out right, give it a couple of feeders and then start the process of fasting it onto talipia, smelts, pellets etc etc.