I've got no plans to add any coral to the tank, just fish only. The only reason I wanted to add only one was that I was concerned about overcrowding the tank with too many fish. I've already got a medium passer angel, medium naso tang, medium yellow tang, large foxface, sharpnosed puffer, two percs, longnosed hawk, royal gramma, three zerba gobies, and three yellow tailed damsels. If I added three more fish wouldn't that be crowding it a little too much for my size tank?