I have a lone RBP about 6" in a 75gal. I am trying to decide whether to raise him by himself, spend big$ to get him a couple RBP tankmates his own size, trade him in and get a school of 4-5 baby RBP, or trade him in and get a lone Black Piranha. I've only ever kept RBP so I don't know a ton about BlackPs except that they are less tolerant of tankmates of ay kind. I'd like to hear the opinions/pros&cons of people who have experience with both. Any info or advice would be appreciated. Thanks.