well i have seen both, soem agressive some less. They are alot less skittish. My large 10" red female red belly can have a red swim in front of her and nothing. Now my 8" red and caribe and my two 7 plus" reds will go freaking nuts as hell! it all depends on the fish but yeah i do think they loose agression if it is just reds, throw a caribe in there and wow makes a world of differance!