Bud you need to do some research before you buy. Everyone here coulda told you that ten blacks would be just one in no time! As far most aggressive, here again, do a little research. This question is asked at least once a week.
*sorry I just started working at petsmart and I am sick of dealing with people asking dumb questions all day so dont take any offense*
But as far as most aggressive goes there is no one fish species that tends to be more aggressive then the others. You could end up with a bad ass axe murderer elong or one big pussy. Its up to the individual fish. However, I must say that my Mac is absolutly phsyco and alot of other Mac owners report the same thing. It is important to remember that it may take weeks or even months ( mine took about 3 months!!) for them to get comfortable and come out of their shell so to speak. So if you do end up with a pussy fish give it a while and see what happens, but even there are no garuntees with Ps.
