Zooplankton Productivity and Growth Performance of Three Fish Species (Oreochromis niloticus, Heterotis niloticus and Hemichromis fasciatus) in Polyculture Ponds in the Binomial Rainforest Zone of East Cameroon

Abstract

One of the major constraints of production aquaculture is due to the partial control of the ecology of fish ponds. The study on the zooplankton productivity in polyculture of the three species of fish according to the type of pond was continued from January to December 2019 in the forest zone with binomial rainfall of East Cameroon in order to optimize production fish farming. For this purpose, 32 ponds including 16 bypass and 16 dam were used. The physicochemical characteristics of the water, zooplankton and fish growth were collected monthly according to standard methods. Transparency (42.64 ± 5.40 cm) and dissolved oxygen ((6.32 ± 1.71)*10-3 mg/dm3 )) values were significantly (p <0.05) higher in bypass ponds. Conversely, nitrites ((0.04 ± 0.01)*10-3 mg/dm3 )) and ammonium ((0.30 ± 0.09)*10-3 mg/dm3 )) which were significantly (p <0.05) higher in the ponds of dam. However, no significant difference (p> 0.05) was observed for temperature, pH, nitrates, ammonium and phosphates regardless of the type of pond. A total of 101 species, 33 genera and 20 family of the three groups of zooplankton have been identified in the bypass ponds. On the other hand, 83 species, 39 genera and 22 family have been identified in the dam ponds. The highest density values of rotifers (7 ± 5 ind/dm3 ) and cladocerans (6 ± 4 ind/dm3 ) were obtained in the dam ponds while that of copepods (6 ± 3 ind/dm3 ) was observed in bypass ponds. The highest values of weight gain (390.28 ± 74.04g) and specific growth rate (0.76 ± 0.05%) in O. niloticus as well as those of weight gain recorded (2227.60 ± 392.35g) and the specific growth rate (0.93 ± 0.04%) recorded in H. niloticus were obtained in the dam ponds. At the end of the study, we recommend that fish farmers practice polyculture of the three species in the dam ponds.