Indian Journal of Animal Nutrition

An outdoor feeding experiment was conducted to assess the efficacy of duckweed (Spirodela polyrrhiza L. Schleiden) incorporated diets in a semi-intensive carp poly-culture system. Spirodela based diets were prepared by 10% (D₂), 20% (D₃), 30% (D₄) and 40% (D₅) replacement of control diet -D₁ (de-oiled rice bran and mustard meal in the ratio 1:1) with sundriedSpirodela and were fed to carp fry (Catla catla Ham., Labeo rohita Ham. and Cirrhinus mrigala Ham.) for 210 days in outdoor cemented tanks. All the species fed on Spirodela diets exhibited significantly higher growth, better condition factor and superior flesh quality. Spirodela incorporation did not affect survival of fish and water quality in any of the treatments. Catla exhibited maximum growth with diet D₂, whilerohu and mrigal recorded maximum growth with diet D₄. Although higher yield was supported up to 40% Spirodela inclusion level (D₅); maximum yield (43.11% higher than the control) was however recorded at 30% Spirodela inclusion level (D₄) and among the different species, L. rohita registered maximum weight gain followed by C. mrigala and C. catla with 16.19%, 19.44% and 12.58% higher muscle protein content, respectively. The results reveal that sundried Spirodela can be incorporated in carp diet up to 30% level for formulating low cost eco-friendly diets for producing high quality fish and higher economic returns.