International Journal of Fisheries and Aquatic Research

Authors
Songmo Berlin – léclair, Efole Ewoukem Thomas, Nana Towa Algrient, Tendonkeng Fernand

Abstract
The assessment of zooplankton productivity in polyculture ponds of three species of fish was carried out from January to December 2019 in the binomial rainfall forest zone of East Cameroon with the aim of optimizing fish production. For this purpose, 09 different fish ponds including 03 unfertilized, 03 fertilized with chicken manure and 03 fertilized through an intra-pond compost bin were used. The physicochemical characteristics of the water, zooplankton and fish growth were collected monthly in the various production ponds using standard methods. At the end of the study it emerges that the values ​​of transparency, pH, dissolved oxygen, nitrites, ammonium and phosphates significantly (p<0.05) varied with the modes of breeding. The highest nitrite (0.05 ± 0.01 mg/l) and ammonium (0.37 ± 0.11 mg/l) values ​​were recorded in ponds fertilized with chicken droppings. For transparency (35.37 ± 4.47 cm) and dissolved oxygen (5.97 ± 1.03 mg/l), the highest values ​​were recorded in unfertilized ponds. However, no significant difference (p>0.05) was observed between the husbandry methods with regard to temperature and nitrates although the higher nitrate values ​​ (3.83 ± 1.03 mg/l) were recorded in intra-pond compost ponds. A total of 101 species of zooplankton, 33 genera and 20 families were identified regardless of the farming methods. Of these 101 species, 91 were present in all the different farming methods. The densities of rotifers species (59) were the highest, followed by cladocerans (19) respectively in ponds fertilized with hen dung and through the intra-pond compost bin and the weakest (36 rotifers and 10 cladocerans) in unfertilized ponds. Densities of copepod species (05) were higher in the unfertilized pond. The average weight values ​​of fish species were significantly (p˂0.05) affected by farming methods. The highest values ​​of mean weight (362.50 ± 77.24 g), specific growth rate (0.75 ± 0.06 %g/j) and Fulton’s condition factor K (3.57 ± 0.77 g/cm) of Oreochromis niloticus and Hemichromis fasciatus were recorded in ponds fertilized with chicken droppings. As for Heterotis niloticus, the highest values ​​of mean weight (1825.00 ± 502.95 g) and specific growth rate (0.88 ± 0.08 %g/d) were obtained in compost ponds. In view of the results, we can recommend that fish farmers should practice Oreochromis niloticus the breeding in ponds fertilised whit chicken manure and the other hand Heterotis niloticus breeding of in intra-pond compost.