WWW.WAS.ORG • WORLD AQUACULTURE • SEPTEMBER 2014 47 (CONTINUED ON PAGE 48) The stocking combinations were: 1) carp only, 2) carp and prawn, 3) carp, prawn and dedhuwa, 4) carp, prawn and mara, 5) carp, prawn and pothi, 6) carp and dedhuwa, and vii) carp and pothi. Carp, prawn and pothi were stocked by ten farmers each whereas carp only, carp and dedhuwa, and carp and pothi were stocked by 24, 30 and 32 farmers, respectively. Farmers stocked fingerlings of rohu (35 ± 2 g), mrigal (6 ± 1 g), silver carp (2.7 ± 0.3 g), bighead carp (7 ± 2 g), dedhuwa (0.99 ± 0.01 g), mara (1.39 ± 0.01 g) and pothi (1.94 ± 0.04 g) in March 2010 and juvenile prawn (0.21 ± 0.01 g) in July 2010. Fingerlings of rohu, mrigal, silver carp and bighead carp were procured from the nurseries of RIDS and FDC, Bhandara and dedhuwa and pothi were collected from the ponds of IAAS and mara from natural ponds of Sarlahi District. The project supported RIDS to establish a nursery in Kathar as a partial support towards making the organization sustainable. Prawn juveniles were transported from a private hatchery of Mymensingh, Bangladesh. Juveniles were transported by flight in oxygenated plastic bags from Dhaka to Kathmandu, and by van from Kathmandu to IAAS, Rampur where these were nursed for 30 days in ponds. The stocking densities used by farmers were: carp 1/ m2, prawn 0.5/m2 and SIS 3/m2. Urea and diammonium phosphate were applied at 0.4 g N/m2/ day and 0.1 g P/m2/day (Knud-Hansen et al. 1993), respectively. Farmers fed fish with farm feed ingredients such as rice bran, mustard oil cake, soybean cake and corn flour at 3 percent of body weight (Rai et al. 2010). Growth and production were monitored by two field supervisors and three research students. Fish were harvested in December 2010 after 270 days of production, whereas prawn was harvested after 160 days. During the production period, farmers regularly harvested SIS (up to two times per month after breeding of stocked brood SIS) for family consumption after three months of stocking, whereas carps and prawn were harvested all at once at the end of the culture period. Farmers obtained an extrapolated total production of carp, SIS and prawn of 3.2 t/ha/y. Total production was greater in Chitwan (3.6 t/ha/y) than in Kailali (2.8 t/ha/y). Production was greater in ponds with SIS than those without SIS, suggesting a synergistic effect of SIS on carp production. Greatest mean total production (38.9 kg/pond) and carp production (36.0 kg/pond) was obtained in carp-dedhuwa-prawn polyculture in nine months, which was 41 percent greater than carp polyculture. Among SIS, pothi and dedhuwa performed better than mara. Average production of pothi, dedhuwa and mara was 3.6, 2.7 and 0.9 kg/pond in 270 days, respectively. Mara bred only in a few ponds, which affected the size of partial harvests and overall production. Small fish contributed 10 percent to total production in Carp-SIS-Prawn polyculture ponds. Prawn production was very low due to high mortality. Therefore, the contribution of prawn to total production was negligible (<1 percent). Fish Consumption Carp was the major food from the pond consumed by households: 64 percent of total production was consumed by the family, ranging from 3 to 45 kg per household in 270 days. Average fish consumption per household was 21 kg in 270 days, equivalent to a per capita fish consumption of 4.8 kg/y, whereas the average national fish consumption rate in Nepal was 1.8 kg/yr (Ministry of Agriculture and Cooperatives 2009). Small fish consumption ranged from 0.5 to 6.4 kg per household in 270 days (maximum 23 g/capita per household per day over 270 d). Small fish contributed an average of 20 percent of total family consumption among SIS-growing farmers. Fish consumption was greater in ponds with SIS than without SIS. Farmers growing SIS carried out regular partial harvests of these fish, increasing household consumption by 38 percent over carpgrowing households (Fig. 1). Farmers consumed fresh and sundried SIS. A few farmers preserved excess dedhuwa by sun-drying for later consumption (Fig. 2). Micro-nutrients in SIS Vitamin A, iron and zinc in SIS were analyzed in a laboratory at the University of Copenhagen. Samples (n=36) of dedhuwa, mara and pothi were collected from farmers’ ponds. Among the four SIS, vitamin A content was greatest in mara, whereas iron and zinc were FIGURE 1. Ms. Bhagawati Mahato collecting dedhuwa from netting for preparation of a fish curry. FIGURE 2. Sun-drying surplus dedhuwa on bamboo plates for future consumption.
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