Brackishwater aquaculture is done mainly in fish ponds located in coastal areas.Marine culture employs either fish cages or substrates for molluscs and seaweeds such as stakes, ropes, and rafts.Accumulation of anoxic sediments below cages due to fecal and waste feed build-up; market competition, especially for export produce; conflicts/failures, social disruption; consumption of wood and other materials.
Freshwater: health risks to farm workers from waterborne diseases.
It began in China, possibly due to the desires of an emperor to have a constant supply of fish.
It is speculated that the techniques for keeping fish in ponds originated in China with fishermen who kept their surplus catch alive temporarily in baskets submerged in rivers or small bodies of water created by damming one side of a river bed.
These practices include: (i) freshwater pond culture; (ii) rice-fish culture or integrated fish farming; (iii) brackishwater finfish culture; (iv) mariculture involving extensive culture and producing fish/shellfish (e.g., oysters, mussels, cockles) which are sold in rural and urban markets at relatively low prices.
Source: ADCP Aquaculture Regional Profiles, 1989b Extensive systems use low stocking densities (e.g., 5 000-10 000 shrimp post larvae (PL)/ha/crop) and no supplemental feeding, although fertilization may be done to stimulate the growth and production of natural food in the water.
Water change is effected through tidal means, i.e., new water is let in only during high tide and the pond can be drained only at low tide.