Quote Originally Posted by greenmonkey51
Also the shape of a bettas tail has nothing to do with agression. Its like saying an albino BP is more agressive than a normal.
Not true. I learned about the aggression of crowntails from a person who keeps and breeds hundreds of bettas - crowntails, double tails, super deltas, and halfmoons.

Also I know this from personal experience. My crowntails are much more apt to flare and try to go after their next-door neighbors than your average veiltail betta.

I have no experience with barbs, but I remember reading about fin nipping - I equate this with aggression.