Freshwater Fish Nutrition

Nile tilapia (Oreochromis niloticus) fingerlings were reared in earthen ponds at three different feeding frequencies; twice daily, twice after 1 day, and twice after 2 days for a period of 7 months. Three hundred and seventy five fish were stocked into each of the nine, 150 m 2 ponds with three replicates for each treatment. The fish were fed with a commercial diet (26% crude protein).

Development of ecofriendly and efficient fish feed for best growth performance is an important step in the field of fisheries and aquaculture. A feeding trial was conducted to compare the effect of Duckweed (Lemna minor) and soybean Glycine max (L) meals as a source of protein on the growth performance, growth hormone level and proximate composition of Grass carp, Ctenopharyngodon idella (Valenciennes, 1844) and Silver carp, Hypophthylmichthys molitrix (Valenciennes, 1844) in monoculture system and in combination. Two 35 % protein experimental diets, F SBM (feed containing 21 % soybean meal) and F DW (feed having 21 % duckweed) as a source of protein were prepared and fed for 12 weeks. At the end of experiment, juveniles of C. idella showed a non-significantly higher growth rate as compare to H. molitrix when fed F DW while H. molitrix showed a higher growth rate in response to F SBM diet in both culture systems. A similar trend was observed in Percentage weight gain (% WG), specific growth rate (SGR %) and feed conversion efficiency (FCE %). The growth hormone level of Juvenile C. idella fed F DW were significantly (P<0.05) higher in both culture systems while same trend was shown by H. molitrix when fed F SBM diet. Proximate analysis showed approximately similar composition of both diets. The results of this study indicate the use of duckweed as a protein source in fish feed.