Water supply by gravity to a fish farm and its rearing devices and structures is important. This saves energy and, consequently, large amounts in terms of production costs.
The water supply to rearing devices can be done in two different ways. The rearing devices can be supplied either in parallel (separately) or in series. If the rearing tanks are connected to the water supply in series, the freshwater should be used first in tanks/ponds of younger fish, from where water flows into the tanks or ponds of older age groups of fish. Although arranging tanks in series is rather frequent, construction of new tanks should prioritize parallel water supply.
Especially in the case of a surface water* source, the construction of a water reservoir at the highest point of the fish farm will facilitate easy and efficient water management. The elevated central water reservoir will serve as a buffer, where water also settles. The water from the reservoir can be channelled to the rearing devices and structures through open canals, pipes or through a combination of these.
The rearing water should contain as much DO as its temperature allows. Aeration* ensures saturation of arriving water with air/oxygen. Aeration with a machine or the injection of pure oxygen* are very efficient techniques, but they are expensive. However, there are simple solutions/devices that can increase the DO of the arriving water.
Drainage of rearing devices and structures should also preferably be done by gravity in the simplest way possible.
At the point where water leaves rearing tanks and ponds, screens should be used. The mesh size of these screens should be dense enough to prevent fish not only from escaping but also from sticking into the screen or between the bars.
