INFLUENCE OF Rhizoclonium MEAL WITH METHIONINE SUPPLEMENTATION ON GROWTH AND SURVIVAL PERFORMANCE OF NILE TILAPIA Oreochromis niloticus FRY

Feed additives are being used in aquatic feeds to ensure that the dietary nutrients are ingested, digested, absorbed and transported to the cells of fish. The experiment was conducted to investigate the effects of Rhizoclonium riparium var. implexum dried powder with methionine (MET) supplementation on the growth, feed conversion ratio and survival performance of Nile tilapia, Oreochromis niloticus fry as partial replacement for fishmeal. Fry were fed five diets with Rhizoclonium meal and containing inclusion levels of MET, namely, 0 (negative control), 5, 10, 15 and 20 g kg^-1. The feeding trial lasted for 6 weeks.

Results of the growth trial showed that the final weight (FW), weight gain (WG), specific growth rate (SGR), feed intake (FI), feed conversion ratio (FCR) and survival rate of all experimental fish were statistically similar (p<0.05). The group fed 15 g MET kg^-1 diet exhibited higher FW (4.54±0.32g), WG (4.21±0.32g), SGR (1.72±0.03) and FI (6.2±0.12g) than did negative control and other treatment groups (p>0.05). The group fed 15 g MET kg^-1 also exhibited lower FCR (1.49±0.09) than did the control group (p>0.05). However, results showed statistically similar survival rates of Nile tilapia fry among all treatments. Thus, the inclusion levels of methionine on diets with Rhizoclonium meal have no significant effect on the growth and survival of Nile tilapia fry. Rhizoclonium meal could partially replace the fishmeal and could also promote better growth and feed conversion efficiency with or without methionine supplementation kg^-1.