Length–weight relationships and condition factors of six fish species caught using gill nets in a tropical African reservoir, Zimbabwe

Abstract

ABSTRACT This study was carried out to fill a knowledge gap and provide useful information for fish management and conservation in the Malilangwe reservoir. Length–weight relationships and condition factors (K) of six fish species, Oreochromis macrochir, Oreochromis mossambicus, Hydrocynus vittatus, Clarias gariepinus, Oreochromis placidus and Labeo altivelis, were investigated in Malilangwe reservoir, Zimbabwe between February and October 2011. Samples were collected monthly with seine and gill nets during three seasons: hot-wet (February to April), cool-dry (May to August) and hot-dry (September to October). The length–weight relationship had a significant positive correlation (r>0.5) for the six species. The growth exponent (b) indicated a negative allometric growth for seven species (b range = 1.52–2.81). Condition factor (K) values were greater than one (1.34–9.29) for O. macrochir, O. mossambicus, C. gariepinus, O. placidus and L. altivelis while it was less than one for H. vittatus (0.82–3.09). The value of K varied with seasons. The study provides new information on length–weight parameters for O. mossambicus and O. placidus.