Otolith morphology of six species of Cichlidae from Lake Buyo in the South-west of Côte d’Ivoire

Abstract

The morphology of otoliths is used as an indicator of various ecological processes or properties. So the present study was aimed to provide baseline data on the morphology of otoliths in six species of Cichlidae. A total of 179 individuals belonging to six species of the Cichlidae fished in Lake Buyo in June 2021 by artisanal fisheries. The sagitta of these species studied present common morphological characteristics. Indeed, they are elliptical in shape and robust with a concave internal face and a convex external face. However, there are a few differences that help distinguish each species. In the relationships between the total length of the fish and the length of the otolith, the values of the allometry coefficient "a" are between 0 and 1 (0 ˂ a ˂ 1) for all the species considered; they reflect a lowering allometry between the length of the fish and the length of the otolith. The values of the coefficient of determination are very high in Sarotherodon melanotheron (r2 = 0.8961), Oreochromis niloticus (r2 = 0.8469) and Coptodon zillii (r2 = 0.8403). These values reflect a strong correlation between the total length of the fish and the length of the otolith of each species. Our study, in the Ivorian or West African context, has the advantage of providing, on the one hand, morphological data on the otoliths of freshwater fish and, on the other hand, means of estimating the size of fish at from those of the otoliths.