Ichthyological Bulletin; No. 17

Among the most difficult problems of the systematist are certain groups of tropical fishes, notably the Parrotfishes and the Lethrinidae, whose bright colours fade quickly after death. Both of these groups are especially abundant in the Indo-Pacific. The Parrotfishes are troublesome enough, but the species do tend to retain the same livery fairly constantly in life, and there are several features that provide well defined generic cleavage, as well as useful clues to species. The Lethrinidae are more difficult, having fewer variable features. Even dimensions, e.g. relative depth, are useful only when comparable stadia can be compared, as considerable general change in body shape may occur with growth. Under the water these are troublesome fishes to identify, as most species are camouflaged by an intricate pattern of cross bars, cloudy patches, and reticulations, which make them all look much alike. In addition, they are among the most wary of the reef fishes, and difficult to approach for close scrutiny. Fresh from the water, the concealing, darker, cross markings and reticulations usually fade within a few moments, and some species are not difficult to recognise, since just after death, colour and pattern are normally reasonably constant within one species, a few are almost constant, others show variation round a typical pattern.Rhodes University Libraries (Digitisation