As some of you know I have a pond I need to stock, and I want to get a pacu to go along with my 13" oscars. The thing is will there be any aggression, and how big should I get the pacu?
Larger Oscars are usually very gentle towards large characins/cyprinids. I would reccomend the pacu(s) be at least 8 or 9'' if they were not brought up with the oscar(s). Just to be safe.
Remember that many pacus can get more than four feet long and easily over 100 lbs, and can consume tankmates.