My 13" Afro has killed my royal clown knife and reticulata ray, and still nips at all of my polypterus ranging from 6 to 12 inches.They are not friendly fish from what I've seen with mine or what I have read on this forum. I recommend selling 2 or buying two. I tried breaking lines of sight, dividers, basically everything but separate them. Oddball said he had luck reintroducing conspecifics at 18-20" inches but I'm not sure if that was an exception or the rule.