The Effects of Substituting Fishmeal Based-Diet With Plant Based-Diet on Nile Tilapia (Oreochromis niloticus) Fish Growth, Feed Efficiency and Production Cost-Effectiveness

Aquaculture started in The Gambia in 1979 but is still at a rudimentary stage. Many government and private interventions conducted on fish farming failed due to the high cost of feed. Fishmeal based diets are expensive thus using them makes many fish farming in the developing countries unprofitable businesses. There is a need to use locally available plant ingredients to develop fish feeds. This study was conducted to compare the growth, feed efficiency and production cost-effectiveness of the Nile tilapia (Oreochromis niloticus) fish fed on fishmeal-based diet (control diet) to that of the same fish fed on plant-based diet (test diet). The two isonitrogenous (30 % CP) experimental diets were tested on 0.81g Nile tilapia (Oreochromis niloticus) fry for a period of six (6) weeks. The control diet composed of fishmeal, soybean meal, cassava flour, and a blend of palm oil and fish oil premixed with mineral and vitamin supplements. The plant-based diet consisted of groundnut cake, wheat flour, brewery waste and rice bran supplemented with mineral and vitamin premixes. Regarding growth performance parameters, there were significant differences between the final mean weight, mean weight gain, percentage mean weight gain and the specific growth rate of Nile tilapia (Oreochromis niloticus) fish fed on the control diet and the plant-based diet. For feed efficiency parameters, there was significant difference between feed conversion ratio for fish fed the control diet and the plant-based diet. However, there was no difference between the fish fed the two diets with regards to the protein efficiency ratio or survival rate. The plant-based diet was inferior to the fishmeal-based diet in terms of growth and feed efficiency parameters of 0.81g Nile tilapia (Oreochromis niloticus) fry. When compared to the fish-meal based diet, the plant based-diet was more cost-effective in producing a kilogram of feed but less cost-effective in producing of a kilogram of fish. Therefore, a plant based-diet cannot replace a fishmeal based-diet without compromising Nile tilapia (Oreochromis niloticus) fish growth performance and production cost-effectiveness.