author(s)
Neha Sharma, Syed Shabih Hassan and MD Ansal

abstract
Experiment was conducted in (80m²) outdoor cemented tanks for 180 days to assess the efficacy of press mud incorporated diets in semi-intensive carp polyculture system. Experimental diets were prepared by 15% (D₂), 20% (D₃), 25% (D₄) and 30% (D₅) replacement of rice bran (i.e. 50 %) of basal diet-D₁ (de-oiled rice bran and mustard meal in the ratio of 1:1) with dried press mud. These diets were fed to Indian major carp fry (Catla catla Ham., Labeo rohita Ham. Cirrhinus mrigala Ham) and exotic carp fry (Cyprinus carpio Linnaeus) stocked @ 10000/ha (80 per tank). The diets were fed @ 10% fish body weight (BW) for the first month, 3% BW for the second month and 1.5% BW for the next two months and @ 1% BW for the following months. All the species fed with press mud based diets reflected better condition factor which indicates better health and condition of fish. Press mud inclusion had no negative effect on the flesh quality of all the fish species. As compared to control, press mud incorporation supported higher or comparable growth in L. rohita with 20 % (D₃) and 25 % (D₄), in C. mrigala with 20-30% (D₃-D₅) and in C. carpio at 30% (D₅) rice bran replacement level; however, growth of C. catla declined significantly with press mud based diets. The maximum yield was recorded in control (Diet-D₁) comparable to this was D₂. Comparative net profit of experimental diets with respect to yield and feed cost reduction was also evaluated. Among the different treatments maximum fish harvest (6.089 kg) was recorded for diet D₁ (control) followed by D₂ (5.704 kg), D₃ (5.633 kg), D₄ (5.546 kg) and D₅ (5.450 kg). As compared to control 6.32 %, 7.49 %, 8.87 % and 10.49 % less fish biomass were recorded with diets D₂, D₃, D₄ and D₅, respectively. Lowest FCR was recorded for diet D₃ and D₂ (1.62 and 1.63) followed by D₁ (1.74), D₄ (1.77) and D₅ (1.84). Cost of feed decreased by 5.19, 6.96, 8.67 and 10.44 % in diet D₂, D₃, D₄, D_5, due to press mud incorporation. Maximum net profit with respect to fish harvest and feed cost was recorded for D_1, which was 3.16 % higher than D₂ followed by D₃, D_4, and D₅. The net profit and total fish harvest from press mud incorporated carp diet in different treatment (D₂ -D₅) were found to be comparable to control diet. The resulting lower FCR in 20 % and 15% level of press mud inclusion diet (1.62 and 1.63) showed that these feeds are efficiently used by the fishes. The results of present study reveal that press mud inclusion at all levels (15 - 30%) in carp supplementary diet did not affect water quality parameters, plankton productivity, survival, growth and flesh quality of fish. Hence, both these diets can be efficiently used to replace control diet. The results reveal that press mud can be included in carp diet up to 30% level for formulating low cost diets for production of good quality economical carp fish production.