I just got a 20 gallon aquarium and have no fish in it yet. I'm looking for something similiar to a piranha that doesn't require to be schooled with other fish, and will do fine in 20 gallons. The only petstores around here are Petsmart and Petco, and neither sell carnivorous fish, so help with a good online store for buying exotic fish and such would be greatly appreciated. I live in the Texas area by the way and only want something legal to own.