I have 3 balas (about 3 inches each), 1 ck (4-5 inches), 1 gold severum (2.5 inches), 1 senegal bichir (3 inches). So far, so good. No problems at all. Will a pink kisser about the size of the severum work? I've been reading on these fish and it seems as if they are aggressive. I don't want it killing off my clown knife, severum, bichir or balas.