Are these the "blue dolphins" that were recently imported (recently being 6-10 years ago now)? If so I was buying the heck out of them at auctions before people really knew what they were. I had ~10+ in a 120 gallon (5' tank) and they did well, but I only kept them for about 1.5-2 years to facilitate easier relocation of the tanks when moving between residences, so they never did get full size during the time I had them. They were aggressive, but not "demasoni aggressive" - more like "zebra aggressive".