Comparative studies of the feeding capacity and preference of Aphyosemion gularis (Boulenger 1901) on some aquatic macroinvertebrates.

ABSTRACT

Background & objectives: An efficient larvivorous fish must show a predilection for mosquito larvae in the presence of alternative preys. This study compares the feeding capacity and preference of Aphyosemion gularis exposed to different kinds of aquatic macroinvertebrates. Methods: Various prey organisms such as Anopheles larvae and pupae, Culex larvae, chironomid larvae and ostracods were either singly and/or jointly presented at different densities to the fish and the number of prey consumed in 12 h light and dark periods were recorded. Results: The result showed that in terms of capacity and preference, the fish significantly consumed (p <0.05) more Anopheles larvae than pupae and more Anopheles larvae compared to Culex and chironomid larvae. It was also found that the fish preferred Culex larvae to chironomids larvae while significantly (p <0.05) more Anopheles larvae were consumed compared to the more abundant ostracods. Conclusion: The results indicate that A. gularis is adapted to feed more on Anopheles than Culex larvae on one hand and generally preferred mosquito larvae to non-mosquito macroinvertebrates. The implication of this observation is that the presence of other non-mosquito organisms considered in this study is unlikely to divert the attention of the fish from mosquito larvae, especially Anopheles larvae. The fact that the fish are able to feed on some of the non-mosquito organisms such as chironomids and ostracods, means that they can subsist on these organisms in the absence of mosquito larvae.