Abstract:
The best immersion period and concentration of different plant extracts (Okra and Bitter leaves) that can efficiently remove egg adhesiveness of Clarias gariepinus was assessed in this study. One male and a female C. gariepinus broodstock with weight 1.3kg and 1.4kg, respectively were used for the breeding. Three different concentrations of the okra leaf and bitter leaf extracts comprising of 1%, 3% and 5% and 0.5%, 1%, 1.5% respectively were used. Tannic acid of 0.75g into one litres of water was used as reference de-adhesion agent, while water without tannic acid or plant extracts was used as control. The fish eggs were rinsed with the solutions at different durations of 1, 3, 5 minutes and 30, 60 and 90 seconds for Okra and Bitter leaves, respectively. Each concentration with rinsing time were done in triplicates. All percentage data were subjected to Multivariate Analysis of Variance test, Tukey tests was used as a follow up procedure. Third order Polynomial regression analysis was used to determine the best concentration and immersion period that removed egg adhesiveness of C. gariepinus. The results of the study showed that there were no significant differences (p>0.05) in the percentage non-adhesive egg and hatching of eggs immersed in okra leaf extract, bitter leaf extract and tannic acid solution at lowest concentration. Okra leaf extract at 1% lowest concentration with 1 minute immersion period and bitter leaf extract at 0.5% lowest concentration with 30 seconds immersion period gave the highest fertilization, lowest sticky rate, highest hatchability, highest survival and were not significantly different (p>0.05) from the use of tannic acid solution. Therefore this study showed that okra leaf extract at 1% concentration with 1 minute immersion period and bitter leaf extract 0.5% concentration with 30 seconds immersion period can efficiently remove egg adhesiveness and increase percentage hatchability in C. gariepinus
