Freshwater macrophytes are considered as valuable fish feed ingredients for their rich nutritional profile. Six Lemna minor based pelleted diets LM-0, LM-0-IA-PS, LM-30, LM-40, LM-50 and LM-60 were formulated using the Interactive Fish Feed Designer (IFFD) software. There was no plant ingredient in one control diet, LM-0 while in other control diet, LM-0-IA-PS 3% Ipomoea aquatica and 2% Pistia stratiotes were incorporated. In diets LM-30, LM-40, LM-50 and LM-60, L . minor was incorporated 30, 40, 50 and 60% levels and 3% I. aquatica and 2% P. stratiotes were added to each diet. There was no significant (P>0.05) difference among the six formulated diets, except ash and calorific value. There was significant (P<0.05 ) difference in the fatty acid profiles of the six formulated diets. Significantly (P<0.05) higher total n-3 PUFA content was found in LM-60 diet compared to others. Rohu Labeo rohita fry (0.81±0.01 g) were cultured under six different feeding regimes. The stocking density was 30 fish/aquarium (60 L each). Fish were fed ad-libitum twice daily.
A direct relationship was found between the final body weight of fish and increasing level of L . minor in the diet till LM-50 diet fed group. The growth rate was significantly (P<0.05 ) lower in LM-60 diet fed group compared to other L. minor incorporated diets fed rohu. The specific growth rate showed the similar trend. The feed conversion ratio was significantly (P<0.05 ) lower in LM-50 diet fed fish compared to others. There were significant (P<0.05 ) differences in the proximate composition among different diets fed rohu. Significantly (P<0.05) higher EPA and DHA contents were observed in LM-50 diet fed fish compared to others. The amino acid profile study of six different diets fed rohu showed interesting results. Significantly (P<0.05) higher amylase, protease and lipase activities were found in LM-50 diet fed fish compared to others. The trypsin and chymotrypsin activities were significantly (P<0.05) higher in LM-40 diet fed fish compared to others. Significant (P<0.05) differences were observed in the expression of genes involved in the biosynthesis of fatty acids of fish cultured under six different feeding regimes.