Grow-out Culture

The pearlspot is suitable for culture in confined, fresh and brackishwaters. The fish is cultured on a small scale mainly in the state of Kerala. It is cultured in the traditional manner, in the 'Pokkali' fields (paddy fields). An annual yield of 3 to 5 tonnes is obtained from these fields, of which, prawns constitute 80%, while the mullets and pearlspot form 20%. In mixed-culture operations along with prawns and other fishes ranged from 768.2 kg/ha/3 months at a stocking density of 25,200/ha (24000 prawns + 1200 fish) to 845.4 kg/ha/110 days at a stocking density of 20,300/ha (20,000 prawns + 300 fish) have been reported. The culture of pearlspot is more economical under polyculture system especially with milkfish and mullets than under monoculture.

The fish can attain a marketable size of 120-150 g over a period of 8-10 months. Though growth rate is relatively slow, high stocking density with low input management can yield optimum production. Under monoculture at stocking densities ranging from 20,000 to 30,000 / ha, an average production of 1,000 kg/ha/year can be obtained in brackishwater ponds. The fish can also be reared in the backyard ponds and tanks in the rural areas. Being a herbivorous fish it is suitable for polyculture. Pearlspot farming could be adopted to any scale integrating with other occupations like poultry farming. The poultry droppings form good manure for natural food production in the culture ponds.

Adult fish in the weight range of 50-125 g are stocked in ponds @ 5,000 nos./ha. The fish are fed with supplementary feed @ 3.5% of the body weight (prepared with groundnut oil cake 40%, rice bran 45% and fish meal 15% fortified with vitamin and mineral mix @ 2.5 kg per 100 kg of feed). The feed is supplied in pellet or dough form. The hydrographical parameters desirable for the breeding and seed production of pearl spot are: water temperature 24-32°C, salinity 15-30 ppt, dissolved oxygen > 3.5 ppm, pH 7.0 to 8.0 and transparency > 50 cm. To facilitate egg attachment, the pond is provided with substrate materials such as palmyrah leaves, coconut leaf petioles, coconut husks, wooden twigs, bricks etc. Breeding occurs within 30-40 days of introduction of the brooders. A production of upto 6 lakhs fry/ha/year can be achieved. Harvesting is usually undertaken by draining the water from the ponds and operating a seine net, cast net or a drag net for capturing the fish.