Freshwater aquaculture

Unit 4 - Cultivable fish and their culture methods

4.3.2. Farming intensity
Depending on the stocking density and management of the system three levels of culture are recognized.

1) Extensive prawn culture:
In this system prawns are reared in ponds, reservoirs, irrigation ponds and rice fields. Production is less than 500 Kg/ha/yr. Stocking is mostly form wild sources. They are stocked with either PLs or juveniles at a density of 1-4/m2. There is no water quality management. Organic fertilization is rarely applied and there is no supplementary feeding.

2) Semi – intensive prawn culture:
This system involves stocking of PLs or juveniles usually from hatcheries at a density of 4-20/m2 in ponds. Fertilization is used and balanced feeds are provided. Predators and competitors are removed and water quality and health are monitored. This level of culture is most common in tropics and yields more than 500 kg/ha/yr.

3) Intensive prawn culture:
The prawns are reared in small earthen ponds or concrete tanks up to 0.2 ha, provided with high water exchange and continuous aeration. They are stocked @ 20/m2. High degree of management is required. Nutritionally balanced feeds are provided. A strict control over all aspects of water quality is maintained. This system requires more research particularly on the management of size variation. Therefore semi-intensive mono-culture of prawns is currently not recommended.