Fisheries Information

Fish Farming

In many parts of the world, fish have provided an important part of people’s diets for centuries. During the last hundred years, fish catches have increased rapidly due to technological improvements including more powerful engines and sonar equipment. Despite the fact that growth in fish catches stopped some 15 years ago, over fishing had already caused the worldwide decrease in stocks to become a real problem. The need to increase fish production by fish farming is urgent. The term ’aquaculture’ involves all forms of culture of aquatic animals and plants in fresh-, brackish- and saltwater. Aquaculture has the same objective as agriculture: to increase the production of food above the level which would be produced naturally. As in agriculture, fish farming techniques include the removal of unwanted plants and animals, their replacement by desirable species, the improvement of these species by cross-breeding and selection, and the improvement of food availability by the use of fertilizers. Fish farming can be combined with agriculture, animal husbandry and irrigation practices which can lead to a better utilization of local resources and ultimately to higher production and net profits. This practice is called ’integrated fish farming’ and this subject is extensively dealt with in Agrodok Books.

Advantages of Fish Farming

Fish is a high quality animal protein provider for human consumption.
A farmer can often integrate aquaculture into the existing farm to create additional income and improve water management on the farm.
Fish growth in ponds can be controlled: the fish species raised are the
ones the farmer selected.
The fish produced in a pond are the owner’s property; they are secure and can be harvested at will. Fish in wild waters are free for all and make an individual share in the common catch uncertain.
Fish in a pond are usually close at hand.
Effective land use: effective use of marginal land e.g. land that is too poor, or too costly to drain for agriculture can be profitably devoted to fish farming if it is suitably prepared.

Basic principles of raising fish and building a fish pond

Once agricultural activities on a farm have been diversified integration can be the next step. A farmer can diversify by raising different kinds of crops or animals. The different activities become integrated when the waste products from one activity are used for the production of another crop or animal. For example, animal dung can be used to improve the fertility of the soil, which will increase plant growth. Animal dung can also be used as a fertilizer in a fish pond to increase fish production. By using these methods production on an integrated farm will be higher than on a farm where activities are carried out separately. Production costs can be kept low by using the by products (e.g. stalks and leaves) from the different activities on the farm for fish culture. These by-products form an inexpensive way of making fish feed, which is cheaper than having to buy feed.

The advantages of integrated farming include:

Minimizing of waste products, which improves the local environment.
Decreased need for artificial fertilizers, which can increase profits by decreased production costs.
Increased fish and vegetable production, which can increase household consumption or income.
Decreased dependence on production inputs from outside the farm, which increases the stability of the farm.
Increased productivity and efficiency on the farm.The most important of the above advantages is the decrease in waste products. Improved soil structure, through the use of pond bottom silt in agriculture as fertilizer, means that water is better retained and less erosion takes place. These long-term advantages outweigh any others which lead only to an increase in fish production. The advantages of integrated fish culture mentioned here give a general indication of what can be achieved. Production methods and yields depend on local conditions. For example, farmers in Malawi, Africa adjust their integrated plant-fish culture system each year according to the amount of rainfall. In dry years the farmers grow vegetables on the pond bottom as there is not enough water to raise fish.
The vegetables grow well on the fertile soil at the bottom of the pond, and suffer less from the drought. Both plant and animal by-products can be used as fertilizer for a pond on an integrated fish farm. Applying natural fertilizer increases the amount of food available in the pond, so that the fish need less direct feeding. Some fish can be fed directly with plant waste. For other sorts the waste must first be made into compost. The compost is then used as a fertilizer in the pond, which increases the amount of natural food available, in turn resulting in an increase in fish production.

A special system of integrated plant-fish production:

Integrated rice-fish production. This production system is used commonly in Asia and can be practiced both extensively and intensively according to the local situation. Animal dung can be used as fish food for some fish species, or alternatively as fertilizer for the fish pond. There are various systems in which fish production can be integrated with other forms of animal production e.g. ducks or pigs. Whether fish production can be integrated with other forms of production depends on the local production and marketing conditions. The soil must be suitable for making a fish pond, and suitable fish species must be available.