Eco-Friendly Aquaculture: First-Generation Organic Carps

Abstract

The demand for organically produced fish is becoming increasingly important, and consumers prefer other organic crops as a consensus on a healthy diet. To produce organic fish on a commercial scale, organically produced quality seeds are needed. However, uncertainty in the timeliness and quantity of seed supply is one of the major constraints in organic aquaculture. Therefore, a trial was undertaken for the production of organic carp seeds at the Natural Farming Unit, ICAR-CIFA, Bhubaneswar. During the monsoon season, fully matured male and female broods were selected from organic culture ponds. Females were injected with pituitary gland (PG) extract twice, but males were injected only once through the intraperitoneal route. The first dose was given in the evening hours to the female at 5-6 mg/kg body weight, and the second dose was given 4-6 hours after the first injection at 8-16 mg/kg body weight. Males were injected at the time of the second dose of 4-5 mg/kg body weight. Induced breeding was carried out by mixing two males per female from breeding hapas fixed in organic fish culture ponds. Spawning was performed in breeding hapa, but hatching was performed in circular incubation pools (cement). The spawn (first generation catla, rohu, and mrigal) produced were reared to the fry stage in a large concrete (50 m³) tank following the organic nursery rearing protocol. To enhance fertilization efficiency, liming was regularly performed in cement tanks. For the sustained production of natural fish food organisms in the rearing tanks, a mixture of mahua oil cake, raw organic cow dung, kalabati rice powder, yeast, jaggery, and organic rock phosphate was applied on a weekly basis, and spawn were also fed daily with a supplementary diet at a 1:1 ratio (kalabati rice powder:fish meal). At the end of 15 days, 50,000 rohu, 30,000 catla, and 20,000 mrigals of advanced fry were produced from large concrete (50 m³) tanks. Our study revealed that by following the standard protocol for organic carp seed production, the seeds of three species of organic carp could be easily produced. This is an attempt to produce the organic carp seeds of rohu, catla and mrigal. For the production of organic fish ponds, fingerlings produced from the earthen organic ponds of the IMC were stocked at two different stocking densities (SDs) in triplicate in grow-out pond experiments (SDs: 4,000 no./ha and 8,000 no./ha). The experimental fish were fed pelleted feed prepared from locally available organic feed ingredients at 2% of their body weight. After 15 months of culture, we found that the weight gain of the fish at an SD of 4000/ha was significantly greater and the FCR was lower than that at an SD of 8000/ha.