Had 'em, bred 'em , got rid of 'em. The biggest problem I had with pirhana, including wipples, besides keeping them fed, was keeping the water clean. They were in a 180g with (4) Magnum 330's, (6) power heads pushing 240gph, and (2) power filters rated at 400gph. The colony consisted fo 1m and 3f. I was turning this water over almost 20x per hour. Still had problems at times with keeping the water quality up. Pirhanas are almost as dirty as goldfish!