Cages can either float in the water or be staked into the ground of the pond (in shallow areas of water). They are usually used between tank and pond culture as they make use of the pond water while still maintaining the control of a small area. There is therefore no control of the water quality when using cages and the water in which they are placed must be suitable for the species cultured. The mesh of the cage
should be small enough to prevent the fish from escaping yet large enough to allow water and waste to pass through to the outside.
Small cages (such as those illustrated below) are often used in the Far East for ornamental fish culture as many different species of fish can be housed separately in one waterbody without becoming inter-mixed. These cages are called ‘hapas’ and may be as small as 1 cubic metre.
Cages used in large open waters such as in dams, lakes or the sea must be strong enough to handle rough weather and be easy to access, clean and harvest from. Floating cages should be secured to the bottom or side of the pond to prevent them from drifting away in rough weather. Predators (e.g. otters, leguaans, other
large fish) may be a problem as they make holes in the cages and allow the fish to escape.