From the fifty-one-foot whale shark Rhincodon typus to a less-than-one-half-inch fish in the minnow family--the tiny Paedocypris progenetica --fish certainly carry a lot of weight . . . or do they? A fish's heft in water may vary, but these diverse aquatic animals certainly carry a lot of weight in our ecosystems and environment. From freshwater to ocean habitats, Judith S. Weis offers a fascinating look at these deceptively simple creatures. Fishes...