Cage culture is an emerging technology through which fishes are reared from fry to fingerling, fingerling to table size or table size to marketable size while captive in an enclosed space that maintains the free exchange of water with the surrounding water body Fish can be cultured in one of four culture systems—ponds, raceways, recirculation systems or cages. A cage or net pen is a system that is enclosed on all sides with mesh netting made from synthetic material that can resist decomposition in water for a long period of time. A cage is enclosed on all sides with mesh netting made from synthetic material that can resist decomposition in water for a long period of time. The on growing and production of farmed aquatic organisms in caged enclosures has been a relatively recent aquaculture innovation.
Submerged net bags are fitted in a solid and rugged frame and submerged under the water. Their use is very limited.
The net bags of submersible cages are suspended from the surface, have adjustable buoyancy, and may be rigid or flexible.
The fixed cage is the most basic and widely used in shallow water with a depth of 1-3 meters. It consists of net bag fitted to posts and is normally placed in the flow of streams, canals, rivers, rivulets, shallow lakes and reservoirs, not touching the bottom. Fixed cages are comparatively inexpensive and simple, but their use is restricted.
Floating cages are supported by a floating frame such that the net bags hang in water without touching the bottom. Floating cages are generally used in water bodies with a depth of more than 5 metres. Enormous diversity in size, shape and design has been developed for floating cages to suit the wide range of conditions of fish culture in open waters.