I had 4 tinfoil barbs waiting for him in there, but since he was smaller than expected the tinfoils were a little big (about 6")...so yesterday I bought 4 irridescent sharks, a little smaller than him. They are in another tank right now, just want to watch for signs of parasites before I add them with the Mbu. Maybe later today I'll see. He will be happy, since now all alone in there he looks a little bored.