You are what you are. . . if you're a fish not a tadpole. But when he minnow's best friend grows legs, loses his tail, leaves the water and returns to tell of birds and cows and people -- all of whom the minnow imagines in fishy forms -- he sets out to see for himself. Stranded on the bank, he's launched again by the frog, and has to agree -- willingly, from the depths of his "most beautiful of all worlds" -- that "fish is fish." Slight, but worth seeing for the outraged look in the eye of the left-behind minnow and the nifty cowfish he conjures up.