I have owned Green Sunfish, and have caught the most aggressive bass IMHO the Spotted/Smallmouth hybrids we have here, and Im telling you if you go by size a three spiked Stickleback is one of the meanest fish in the world (if you dont believe me put a2-3 inch three spiked Stickleback in a tank with similar 2-3inch fish and see what happens). If you want to look at BIG aggressive fish I will have to say that a similar sized pound for pound Alligator Gar will most probably destory any Bass (Smallmouth, Spotted, Shoal , Largemouth etc.), I truely believe only the Northern Pike is really any competition in the Natives category.