Abstract:
Aquaponic system is one of the promising alternatives in conserving the scarcely available water by recirculation. Though, there still exist the inherent challenge of imbalance in nutrient input and nutrient uptake for efficient and economical output in the system. Consequently, this research was carried out to determine an efficient feeding rate for economic production of fish and lettuce in aquaponics. This research was conducted by constructing two aquaponics system in which 35 pieces of juvenile catfish of relatively equal average weight were raised and subjected to two different feeding rates of 5 % and 3 % relative body weight of the fishes categorized as treatments A and B respectively. Each system was connected in series to directly utilize the effluent generated with respect to the different feeding rates as nutrient in raising lettuce plants. Another set of lettuce was grown on soil medium to serves as control and classified as conventional. The water physiochemical properties were monitored to determine how it affects the fishes and the plant in the aquaponics systems. Random sampling of fishes average weight and lettuce plant growth parameters in each treatment was carried out weekly in evaluating the fish growth rate, the average yield and productivity of the lettuce using regression analysis, Duncan multiple range test (DMRT) at 5% level of probability, and analysis of variance (ANOVA) at 5% confidence level. The result shows that treatment A has the highest effect on the growth rate of catfish with the highest regression coefficient (R2) value of 93.1% compared to treatment B at regression coefficient R2 value of 92.3%. Also the ANOVA result shows that there was no significant difference in the lettuce yield between the
two treatments. However, the regression coefficient (R2) in treatment B was higher at 76.3%, compared to treatment A at 72.9%. The DMR test shows that none of the treatments is highly significant than the other with mean value of 0.0004. The ANOVAs result for lettuce productivity in the treatments also shows that there was no significant difference in their mean. However, the DMR test shows that treatment A with the mean 0.0831 was highly significant compared to treatment B with the mean value at 0.0787. Consequently, it was concluded that treatment A being 5% feeding rate gives the optimum fish feed usage for economic production of fish and lettuce in aquaponics.
