like CA wrote, the Cyno afra's are pretty aggressive -- the demasoni will hold their own but your labs might get picked on quite a bit by the afra's. Mine are little devils already and are only 2 inches long and 6 months old--still babies. I'm selling them because unlike my other fish, they are maturing very fast and are proving they need a much larger tank earlier than I had anticipated. IMO mature afra's need at least a 75 gallon---they demand large territories.