Keywords: Carp polyculture, growth and yield, women in aquaculture

A farmers field based experiment was conducted to assess the productivity of carp polyculture systems during 20 August – 18 December 2001 at Kathar–1 Kusahana, Chitwan. The experiment was carried out in 115-280 m2 earthen ponds with three treatments replicated thrice. Fish were stocked in three combinations: polyculture of rohu (Labeo rohita), naini (Cirrhina mrigala) and bhakur (Catla catla) at the rate of 0.3, 0.3 and 0.4/m², respectively (T₁), polyculture of silver carp (Hypophthalmichthys molitrix), bighead crap (Aristichthys nobilis), common carp (Cyprinus carpio) and grass carp (Ctenopharyngodon idella) at 0.5, 0.2, 0.1 /m2, respectively (T2) and polyculture of silver carp, common carp, bighead carp, grass carp, rohu, naini at the 0.35, 0.20, 0.15, 0.10, 0.10, 0.10/m², respectively (T₃). Fish were fed daily with locally prepared pellet feed (rice bran and mustard cake, 1:1 ratio) at 2% body weight, Ponds were fertilized by urea and diammonium phosphate to provide 0.15 g N/m²/day and 0.05 g P/m²/day (3:1 N:P ratio) in fortnightly interval. Pond water quality was found to be safe and independent of stocking ratio. Significantly (P<0.05) higher apparent food conversion ratio (AFCR) was in three species carp pllyculture system (T1) (1.70 ± 0.09) than four and six species carp polyculture system. Extrapolated net fish yield of three species carp polyculture system (1.61 ± 0.38 t/ha/yr) showed significantly lower ( P < 0.05) compared to four species (4.63 ± 0.43 t/ha/yr) and six species carp polyculture system ( 4.05 ± 0.63 t/ha/yr). Fish survival ranged between 93.7 ± 6.4 to 100% in different species. Results clearly showed that growth of Chinese carp was better in comparison to Indian major carp in sub-tropical Nepal.