cromis are popluar choice but they might slowly kill each other off
longspine cardinals are my favorite ones
Have 5 differnt schools of fish in my tank. personally believe they will continue to weed out the weakest in the school. from time to time I just pick up more to replace those lost. Just adding 1 want cut it they will probably kill it. Always get as large as possible and add at least 3 or 4 at a time