POTENTIALITY OF Nannochloropsis sp. AS PARTIAL DIETARY REPLACEMENT OF FISHMEAL ON GROWTH, NUTRITIONAL PROFILE, PIGMENT, ANTIOXIDANTS AND BREEDING PERFORMANCE OF GUPPY (Poecilia reticulata

Abstract

In this study, fishmeal was partially replaced by Nannochloropsis sp. to evaluate its effect on growth, survival, proximate composition, pigment, antioxidants, breeding performance and water quality parameters in rearing guppy (Poecilia reticulate). Triplicate groups of fifteen uniform sized guppy fries were kept in each rectangular glass tank (20 L) maintaining the male and female ratio to 1:2. In diets, Nannochloropsis sp. was incorporated by replacing fishmeal at different levels-0 (control), 5 (N5), 10 (N10) and 15% (N15) and commercial feed (CMF) and fed to the fishes, twice a day at 5% of their body weight for 100 consecutive days. At the end of experiment, random sampling of fishes was done for growth parameter assessment and further laboratory analysis. Results showed that the lipid profile was significantly (P < 0.05) higher in 15% inclusion of Nannochloropsis sp. whereas there were no significant (P > 0.05) differences in protein and carbohydrate content in all groups. However, feed conversion ratio, specific growth rate, average daily growth, length increment and condition factor were relatively similar in all the groups except 15% and commercial feed. The carotenoid content of fin and muscle was significantly (P < 0.05) higher in 15% inclusion. In addition, the fish in 15, 10, and 5% inclusions performed significantly (P < 0.05) earlier breeding with a higher number of offspring, respectively than the control and commercial feed fed groups. Statistical analysis of the collected data also revealed that there was significant differences among treatments regarding survival and oxidative stress analyzed by hydrogen peroxide and lipid peroxidation assays. Survival rate was significantly (P < 0.05) higher in algal feed fed groups (N15, N10, and N5). H2O2 was significantly (P < 0.05) lower in N15 compared to the other groups whereas lipid peroxidation was lower in both N15 and N10. The addition of Nannochloropsis sp. to the feed improved and maintained good water quality during the culture period. In conclusion, results from this study indicate that selected marine microalga can improve reproductive performance through enhancing body coloration and lipid content of fish as well improving their survival rate with higher antioxidant properties might help in production of more hardy culture species for commercial aqua farming.