Growth Performance of Heterobranchus Longifilis With Tilapia Niloticus Using Extensive and Semi-Intensive Feeding Regime
Growth experiments using Heterobranchus longifilis and Tilapia niloticus under different culture systems and feeding regimes were conducted in earthen fish ponds in Nigeria. The experiament involved the polyculture of Heterobranchus longifilis and Tilapia.niloticus at different stocking ratios of 20 catfish with 20, 60, and 100 Tilapias at 11,111, 22,222, and 33,333 fish/hectare and fed rice bran / blood meal (20 % protein) alternatively at 2 % body weight, twice daily, seven times a week. The experiment lasted for a period of seven calendar months. Calcium carbonate was used for liming while NPK, Sulphur and chicken droppings were used for the fertilization of the ponds. Physio-chemical measurement for nitrate, nitrite, dissolved oxygen, BOD, turbidity and salinity were taken weekly. The regression equation, correlation coefficient, and coefficient of determination for the length – weight relationship of Heterobranchus longifilis and T.niloticus were high with corresponding high values of coefficient of determination (100r2), which ranged between 56.91 to 97.81%. The rate at which weight changes for every unit increase in length (b values) ranged between 2.317 to 2.438 for Tilapia and 2.419 to 3.082 for Heterobranchus longifilis. The stocking ratio of 1:3 (H. longifilis: Tilapia) fed rice bran / blood meal 20 % protein had the highest mean body weight, and highest combined net production, and the highest fish biomass. While the stocking ratio of 1:1 (H. longifilis :Tilapia) had the highest percentage weight gain, specific growth rate and relative weight gain. No significant difference was observed between the effects of stocking ratio and the mean final weight of fish. Although the effect of feed types on the growth of fish was statistically significant (P<0.05) ANOVA, no significant interaction was observed between stocking density and feed type.