You've seen them before. Perhaps many times before. In the pet stores, at friends, when you visit family, and in public aquariums, no doubt. You're struck by the wide variety of species (nearly 1,500 and counting ). By the beautiful colors of some and by the unique shapes and sizes of others. You think to yourself: How can it be so? How can they all be related? What am I talking about? Cichlids, of course. The family of fish whose relatives can be...