Asian Fisheries Science 24 (2011):354-366 Asian Fisheries Society ISSN 0116-6514 Standardising stocking density for freshwater prawn Macrobrachium rosenbergii (De Man, 1879) farming in coconut garden channels K. RANJEET 1 * and B. MADHUSOODANA KURUP 2 1 PG Department & Research Centre in Aquaculture and Fishery Microbiology, MES Ponnani College Ponnani South P.O., Malappuram (Dist) -679586, India 2 Kerala University of Fisheries and Ocean Studies, Panangad, P.O., Kochi, PIN-682 506, India Abstract The effect of stocking density on the population structure, growth characteristics and production of freshwater prawn Macrobrachium rosenbergii in coconut garden channels was studied. A randomised block design of four treatments andfour replicates was used and the only difference being the stocking densities which ranged from 5000ha -1 to 25,000ha -1 . The mean weight and survival at the time of harvest varied from 55.5 g to 101.7 g and 28.21% to 69.44% respectively. At lower densities the proportion of undersized non-marketable prawns was relatively low. However, net production increased with stocking density from 90.1 (TC-1) to 199.7 kg . ha -1. 8 months - 1 (TC-4). Final marketable yield structure and economics revealed that the stocking density of 15,000ha -1 was optimum for coconut garden channels in Kuttanad. Present study suggests that the profit incurred from freshwater prawnfarming is directly related with production of larger orange-clawed and blue-clawed morphotypes. Hence stocking density was found as an essential component for ensuring better marketable yield and improving the economic returns. This study provides significant information since most coconut garden channels are abandoned water areas which when utilised properly can be an additional source of income especially to agriculture farmers in India and other Asian countries. Introduction Aquaculture production systems used across the world differ widely depending on the species being cultured and on the geographical location and socio-economic context. The pursuit for an alternate eco-friendly and sustainable aquaculture has led to the recognition of giant freshwater prawn, Macrobrachium rosenbergii (De Man, 1879), with the trade name ‘scampi’, as the prime candidate species for freshwater grow-outs. Kuttanad, the rice bowl of Kerala (South India), is traditionally known as the home ground of this species. Traditionally, prawn farming is carried out in polders developed from paddy cultivation (Kurup et al. 2002). Being a low-lying wetland, Kuttanad is governed by a wide array of physico-chemical parameters characterised by low water and soil pH. Since this area is also frequently flooded, a round the year culture of scampi is not feasible. Moreover, paddy being given prime importance, scampi culture is only practiced as part of a crop rotation process. Hence, the duration of culture cannot be extended beyond 5-6 months. Also due to water logging, pre-stocking management practices like drying, raking and liming of the soil cannot be done effectively. Hence, a wide fluctuation in