I have a 75 gallon tank with a lot of rock and plenty of hidding places, some mushrooms and zoo's. The tank is thriving, up and running over two years. My problem is I originally included damsel fish when I first stocked it including a little baby sargent major. Later I added a two inch red v tail grouper. Now I have a 3 inch Sargent major and a 6 inch grouper. I realize that sooner or later the grouper will have to go or the tank will have to get bigger, but I'm looking for any suggestions as to what I can add for a third fish in the meantime that will NOT become fish food! Any advice or comments would be greatly appreciated - what type of fish and size? Thanks. Clem