Book excerpt: Fishes form the largest group of vertebrates, with around 20,000 known species, and they display a remarkable diversity of size, shape, internal structure and ecology to cope with environments ranging from transient puddles to the abyssal depths of the sea. Life in water leads to particular problems for body fluid regulation, locomotion and sensory systems, and these have been resolved in the most ingenious ways. This book, the first edition of which was published in 1982, has been largely rewritten to take account of recent information resulting from the huge rate of publication of scientific papers and books on fishes. With the addition of J.H.S. Blaxter, the expertise of the original authors has been further widened, leading to new chapters on behaviour and on fisheries and aquaculture. A chapter on endocrines has also been added and all other chapters have been brought entirely up-to-date. The second edition includes a large number of new illustrations.