INTEGRATION OF MOLA Amblypharyngodon mola IN PRAWN-CARP GHER FARMING SYSTEMS TO INCREASE HOUSEHOLD NUTRITION AND EARNINGS FOR RURAL FARMERS IN SOUTHWEST BANGLADESH
The fish farmers of the Southwest Bangladesh Khulna region use a combined freshwater prawn (Machrobrachium rosenbergii) and carp (Labeo rohita) culture in seasonal paddy fields, a practice referred to as "gher farming". The farmers typically sell the prawns in overseas markets to fetch higher prices, leaving family members (particularly women and children) malnourished from lack of complete protein and vitamins. The present study sought to mitigate this problem by incorporating nutrient-rich Mola (Amblypharyngodon mola) for home consumption into traditional prawn-carp gher farming systems. Mola is a nutrient-dense, small indigenous fish that self-recruits and lives off natural pond biota. Hence it can be grown at little additional costs to farmers, yet can provide an important source of nutrition for them.
The first experiment investigated the effect of Mola incorporation on prawn production using the following treatments: a traditional prawn-carp culture (T1), a prawn-Mola culture (T2), and a prawn-carp-Mola culture (T3) with stocking densities of 2, 1, and 0.1/m2 for prawn, Mola, and carp, respectively. The biomass produced by the end of the 6-month experimental period is shown in Table 1. Results indicate that production of prawn increases, while carp production is little effected by introduction of Mola. These findings indicate that integrating Mola into prawn-carp gher farming systems has no negative impact on the production of either species and could enhance total seafood production.
A second experiment sought to optimize Mola stocking densities in prawn-carp gher ponds. Three experimental systems were examined containing 2/m2 prawn, 0.1/m2 carp, and either 1 (T1), 2 (T2), or 4/m2 (T3) Mola. A fourth control system (T4) contained only carp and prawn stocked at the same densities. The biomass recorded at the end of the study period was 455.58±14.69, 462.77±15.60, 456.28±13.94, and 362.25±17.84 kg/ha for prawn and 588.11±16.47, 572.19±17.28, 586.75±15.39, and 502.92±16.84 kg/ha for carp in T1-4 while Mola production was 298.55±11.55, 376.21±15.34, and 397.66±18.41 kg/ha in T1-3. Considering the initial stocking weight for Mola in T2 was lower than T4, and final production was similar between the two groups, the results suggest that stocking brood Mola at a density of 2 pieces/m2 in prawn-carp gher farming systems provides optimal production of all three species.
(Supported by the AquaFish Innovation Lab - USAID)