Polypterus are your best bet, most "predatory" fish are pretty wussy since they get by from eating smaller creatures, not hammering other fish like cichlids do. Bichirs just chill and are not commonly targeted by most cichlids
Should be good, just maybe grow the bichirs out to a good size to prevent the oscars from trying to eat them
YesDo I need a lid? I have heard they can be escape artists but is it necessary?
How about a Lima shovel nose catfish? WILL eat feeders if fed them but also like frozen foods
To give you an idea my new senegal torpedoed out within 6 hours of being in the tank. Needless to say, lid has been tight since then.Do I need a lid? I have heard they can be escape artists but is it necessary?