I have to agree. I've seen one breedign pair of cons completely take over half a 130 gallon tank, shoving two 10 inch O's a3/4 grown JD, and Nicaraguense as well as another male con off to one side. The second any of those fish were over the invisible boundary, the dominant male convict was there gills flared out, showing enough attitude to indimidate either of those. Never realy was any fighting per se, since they figured he was serious, but I stopped underestimating cons after witnessing that for a few weeks... lol