Ok ive had my arowana for about a year and a half and hes pretty much had the same tankmates the whole time(2 red tail barracudas and a florida gar). Normally during the day he cruises back and forth with my gar and they get along fine and i dont watch them too much during the night. Tonight he was just being a jerk to the rest of the fish, any time the gar tried to swim with him he tried to bite him. The other thing was I put some goldfish in for everyone to eat and then went back to the computer all of a sudden i hear a big bang and assume they just eating goldfish so i turn around and see my aro with a barracuda sticking outta his mouth. So I run over and kinda grab his tail to make him let go and at first he just doesnt even respond so i try grabbing his head and then he spits him back out. I swear he didnt use to behave like that at night.