i dissagree rxracer. big or small, if a piranha decides to make a snack out of it, they will. people who have had a pleco in the tank for 10 months, all of a sudden find a eaten pleco 1 morning. its random and tank mates are never a guarantee. piranhas are just to unpredictable. but on a side note, i have a pleco in my rbp tank, its been in there for 4 months. still doin good.