hey so i have a 72 gallon bow front that i am setting up , i am buying 3 pygo "black ear" piranha, and i want the best looking set up as possible i was thinking to do natural gravel with a black background help me, or should i do sand , but what type of back ground fake plant backgrond or what im confused, also i think ima plant the tank and put some driftwood, plz give me some ideas. also how big of a shoal can i have in the tank i was thinking 3 was max for the tank size