Substitution of fish meal by duckweed Lemna minor meal in diets for Nile tilapia Oreochromis niloticus
Duckweed meal was used to substitute fishmeal at levels of 0,15,30,47 and 60% in five experimental diets for Nile tilapia, Oreochromis niloticus (mean weight 1.10 ± 0.06g). The feeds were formulated to contain 35% crude protein. Each diet was fed to fish twice daily at 5% body weight per day for 10 weeks. In general, the best growth and feed performance was obtained with a fishmeal control diet. Fish fed the lowest dietary (15%) duckweed diet had comparable result with those that received the control diet. Fish fed higher levels of duckweed meal had depressed weight gain, reduced feed intake and higher mortalities. The adverse effects were probably due to high fibre content of duckweed and reductions in diet palatability. It was concluded that 15% dietary duckweed meal can be incorporated in Nile tilapia diet without significant depression of growth and health of the fish.
Keywords: Duckweed meal, substitution, fish meal, Nile tilapia.