Squamation and scale character stability in cichlids, examined in Sarotheroden galilaeus (Linnaeus, 1758) (Perciformes, Cichlidae)

Squamation and scale morphology provide interesting characters for phyletic analysis within the Cichlidae. It is not known, however, to what extent these characters are genetically fixed or determined by environmental parameters. To clarify this point, a study on Sarotherodon galilaeus was conducted. This species has an extensive distribution and lives in markedly different environments. Most scale characters were found to be remarkably stable within the species. The only large variations occur in scale counts, extent of caudal fin Squamation, number of circuli and radii, and the extent of scale granulation. The Squamation pattern, the form of the circuli and radii, the shape of interradial rostrad projecting tongues, the denticles on the circuli in the rostral field, and especially the kind of granulation in the caudal field is similar in all specimens examined and is also retained in fish bred in aquaria for several generations. Thus it seems justified to assume that these characters are strongly determined by genetic factors and that their analysis can be useful in the determination of phyletic relationships.