Pond culture is the most common culture system of catfish in all parts of the world, and most of the present-day production comes from small- and large-scale pond farms. Though more than one species of catfish may be reared in the same pond, polyculture of the type employed in carp farming is seldom practised. Exceptions are the small-scale rearing of Pangasius with tawes (Puntius gonionotus) andsepat siam (Trichogaster pectoralis) in Thailand, and the grow-out of yearlings of sheatfish in carp ponds. The double-cropping system of channel catfish with rainbow trout in the south-ern USA has already been described in the previous section.
In predominantly catfish-farming areas, preference is usually for intensive farming systems. The hardy nature of the species makes high-density culture possible. Nevertheless, as will be discussed later, excessive stocking densities and very intensive feeding have created several management problems in some areas, such as Thailand.
Raceway culture is one of the intensive systems of catfish farming employed in the USA. Raceways constructed of concrete, asphalt, concrete blocks or earth are used. The degree of production intensity depends largely on the abundance of the water supply. Smaller raceways with water supplies of high volume and high velocity are used for highly intensive production, whereas larger raceways with a lower water flow are utilized for semi-intensive systems of production. A recent development is the use of circular and linear tanks for growing fish to market size.
The catfish Pangasius has been cultured from ancient times in floating bamboo cages in Kam-puchea and Thailand. This system of culture is now carried out in Europe and the USA as well, using new and improved types of cages and feeds. However, cage culture production of catfish in any of these areas is only a small percentage of that of ponds and raceways.
A culture system of some importance in the USA consists of the development and management of what are called fee-lakes, pay-lakes orput-and-take fishing. Operators of such establishments produce their own fingerlings for stocking lakes or ponds, or buy fingerlings from other producers. Recreational fishermen are allowed to fish in these waters for a fee, based on the quantity of fish caught or the duration of recreational fishing.