The biology and taxonomic status of an estuarine population of Pranesus pinguis (Lacépède) (Teleostei: Atherinidae) in south east Africa

Abstract

The biology and taxonomic status of Pranesus pinguis in the subtropical Kosi estuary in south east Africa were investigated. Data from Kosi specimens support the view that P. pinguis is a highly variable species in terms of fin, spines, rays and body ratios. Nearly all the variations reported for P. pinguis by Smith (1965) occurred within the Kosi population. Criteria used to distinguish P. capricornensis, P. ogilbyi and P. insuiarum fall within the range of variation of P. pinguis from Kosi and must therefore be considered synonyms. The diet of P. pinguis in Kosi consisted chiefly of Calanoida and feeding took place at night. The fish congregated in shoals around a reef during daylight. The structure and dimensions of the gill rakers related to the diet indicate that, although P. pinguis feeds mainly by capturing individual prey, it is also a facultative filter feeder. All stages of the reproductive cycle were recorded from P. pinguis in the Kosi estuary. The eggs have a covering of filaments which may allow for demersal attachment. Although no direct evidence was available, spawning within the estuary may occur.