VIABILITY OF CLARIAS GARIEPINUS EGGS STORED IN FORMALIN AT VARIOUS TIME INTERVALS AND DISINFECTED WITH FORMALIN AND BITTER LEAF EXTRACT

ABSTRACT

Various organic and inorganic disinfectants have been recommended for the production of Clarias gariepinus. This study explored the possibility of using an organic and inorganic disinfectant (bitter leaf extract and formalin) in the spawning process of C. gariepinus. Formalin was also used as a  preservative  to determine the viability of C. gariepinus eggs stored in formalin at different concentrations and time intervals. The first range finding test was carried out to determine the effect of formalin at concentrations of 4%, 3%, 2%, and 1% stored for 30mins. Five treatments were used. The second range finding test was carried out using lower concentrations of formalin 0.5%, 0.2% and 0.1% and for different time intervals, 15 minutes, 10 minutes, and 5 minutes respectively. 4 treatments were used. 0.1% concentration of formalin and 20% concentration of bitter leaf extract was used for the disinfection experiment. 3 treatments; control, formalin treated eggs and eggs treated with bitter leaf extract having 3 replicates each were used. The results obtained showed significant differences (p<0.05) in the fertilization, hatching and survival rates between the formalin dip and the bitter leaf extract.  Between both disinfectants, the eggs treated with bitter leaf extract had the highest fertilization, hatching and survival rates with mean values of 77.03±6.51%, 64.53±11.80%, and 98.36±2.44% respectively. Although highly utilized as a broad-spectrum chemical in the aquaculture sector, formalin has a negative effect on the eggs of C. gariepinus in the concentrations that were used for this study, as both a preservative and a disinfectant. Bitter leaf extract having immunological and antioxidant properties is however recommended for use in the artificial propagation of C. gariepinus, as it had the best survival rate of fry during the course of this study.