the dovi its there teeth.they punture the lips of other fish at even if the other fish are bigger.i have seen a wild full grown male in costa rica wow what a set ! iwanted to see if the badest could live in a big tank to gether f/h red/dev, dovi ,ect ,i was glad to get him out, ripped lips, his teeth would go right thro when they jaw lock about 8inch only a baby really .but again all fish have diffrent temperment he would just hold his ground if started on but that was enuf he probably would be worse or be more pushy if bigger.never kept a talipia or some of the others its not always abound teeth it ,some fish have just got that jack russel thing going on as well,my 4 inch nigranese puts all the others in there place if they mess will him lol, does hit and run does not care what size they are saw them in the river with the dovi to, does no damage tho just mind the eyes a......