Bettas, sometimes known as fighting fish, are tropical Asian varieties having spectacular waving tails and fins. They're available in a wide range of colors. This ''Pet Handbook'' gives expert guidance on the selection and care of bettas, plus advice on segregating them from less pugnacious fish. ''Barron's Pet Handbooks'' are written by breeders, trainers, and veterinarians, they present expert advice on feeding, health care, housing, breeding, and all other important aspects of pet care. They are filled with vivid color photos and instructive line art.