Harnessing the Potential of Naturally-stabilized Earthen Ponds for Hill Aquaculture: A Demonstration Using Fish Species Combinations in Meghalaya

Aquaculture plays a pivotal role in sustaining livelihoods in the hilly regions of India. However, these areas face challenges in aquaculture production due to prolonged cold climates and suboptimal water temperatures. This study aimed to develop a low-input aquaculture system tailored for hilly conditions in Meghalaya, Northeast India, by employing naturally-stabilized earthen ponds. Ranging in area from 700 to 1500 m2 and with a depth of 1.5 to 2m, these ponds were stocked with fish of different feeding niches at a density of 5000 fish per hectare, with the following compositions: 20% Catla, 40% Rohu, and 40% Gonia in Pond 1; 20% Catla, 40% Rohu, and 40% Common carp in Pond 2; and 20% Catla, 40% Rohu, 20% Gonia, and 20% Common carp in Pond 3. The average size was 28.4±1.8 g for Catla, 7.5±0.4 g for Rohu, 7.6±0.5 g for Gonia, and 10.8±1.3 g for Common carp. The culture duration spanned 8 months, with the initial two months involving feeding fish with commercial feed and the subsequent 6 months with farm-made feed at 2% body weight. Monthly assessments of water quality parameters and bi-monthly evaluations of fish growth attributes were conducted. Analysis of water temperature revealed suboptimal average temperatures ranging from 19.5°C to 20.2°C. Fish production attributes at the end of 8-month was found to be better in Pond 2 (survival 83.2%; biomass 1227.5 kg/ha; FCR 1.53), followed by Pond 3 (survival 82.3%; biomass 1114.8 kg/ha; FCR 1.60) and Pond 1 (survival 81.1%; biomass 998.7 kg/ha; FCR 1.64). Ponds containing Common carp exhibited lower biomass, potentially due to their aggressive feeding behavior leading to competition with co-habiting fishes. It is concluded that naturally-stabilized earthen ponds in hilly areas could serve as a valuable resource for hill aquaculture. However, optimizing productivity requires appropriate fish combinations to minimize inter-specific competitions.