It is an established fact that protein from foods of animal origin is dangerously lacking in the everyday diet of much of the population of Africa. This deficiency is responsible for a great deal of ill health and many deaths each year in almost all the countries of Africa including Rhodesia and Zambia. Even in the absence of ill health, protein deficiency leads to poor growth, muscular weakness and an increased susceptibility to many diseases. The supply of meat from game, various domestic animals and fish from natural waters has so far failed to provide the population with the balanced diet needed. It is imperative therefore to increase protein production by all possible means, first by the intensification of the existing means of production, and second, by the introduction and development of additional sources of protein.
Fish culture in artificial waters is one of the best ways of increasing the availability of food rich in protein. One of the advantages of fish culture is that the protein it produces is generally more economically obtained than that of agriculture, which calls for nitrogenous fertilizers for fodder production, and protein concentrate supplements for feeding livestock, cattle, pigs, poultry, etc. Another advantage is that animal protein produced in fish ponds may exceed the production from agriculture on an equal area. That animal protein may be produced in ponds cheaply and in large quantities is important to a national economy. Low production costs mean low food prices, which, in turn, influence the general cost of living.
Fish is high quality food. It contains as much as 60 percent first class protein on a dry matter basis. It is rich in vitamins and also contains variable quantities of fat, calcium, phosphorus and other nutrients important to human health and growth. Fish in many ways is even more nutritious than most meats from warm-blooded animals. Nutrition experts agree that fish with the addition of a variety of vegetable products constitutes a completely balanced diet.
The cultivation of animal and vegetable life in a water is known as aquiculture. All kinds of water are used — sea water, brackish water and fresh water. Fresh water for aquiculture is used in artificially built ponds and reservoirs, as well as the fresh water of natural lakes, rivers and streams.
Aquiculture takes many forms, such as, for example, growing fish, frogs, oysters, rice and vegetables. A branch of aquiculture dealing with fish is called pisciculture or fish culture. Fish culture may be combined with other cultures, either animal or vegetable.
The variety of kinds and conditions of water calls for different methods of fish culture in natural as well as in artificial waters.
The aim of fish culture is always to achieve the highest possible fish production in any given circumstances and in the most economical way. Complete control over the physical, chemical and biological factors, which either directly or indirectly influence fish production, can rarely be achieved by management in natural waters. Despite good management, production may be limited by such factors as water which is too deep, absence of essential fertilizers, excessive invasion by water plants, undesirable composition of the fish population, and so on. In artificial waters, on the other hand, these adverse factors can be kept under control and a high fish production achieved.
Fish culture in natural waters is usually extensive and in artificial waters intensive. In either case extensive or intensive ways of management may be applied. Fish culture in ponds is always associated with intensive management.
Cultivation of fish in a variety of waters under different climatic conditions requires different approaches. Methods of fish culture used in salt, or brackish waters, or in temperate climates, are not described in this manual, as in central east Africa we are only concerned with fish culture in the fresh waters of tropical and subtropical zones.
Since in central east Africa both the warm and cold climatic zones exist, the critical dividing factor for either warm or cold water fish is a temperature of 11°C (52°F). Typical tropical fish do not survive water temperatures below 11°C for any length of time, whereas subtropical fish can resist fluctuations of temperature to below this point without harm.
Special chapters deal chiefly with fish culture in artifically built ponds, reservoirs, dams and lakes. With few exceptions all these waters are warm, so that the prevailing type of fish culture in central east Africa is warm water fish culture.
Fish culture in both ponds and reservoirs is undertaken mainly to produce fish for food. Sometimes, especially in reservoirs, fish is cultivated for recreational purposes. In addition, ponds are used to produce fish for stocking other ponds, fish for sanitary purposes and ornamental fish.
As to varieties, in central east Africa the culture of warm water fish, such as the species of the Cichlid family, predominates. Cold water fish such as trout are cultivated to a lesser degree. The warm water varieties also include such exotic fish as tench, black bass and bluegill. One of the latest introductions is carp, which is adaptable to cooler waters as well.
In principle, all artificial waters could be regarded as ponds if they conform to the following requirements:
They must be shallow.
It must be possible to drain them.
It must be possible to keep ponds dry or under water alternately for certain periods.
Not all artificial waters conform to these requirements. Some are closer in character to natural waters, others to proper fish ponds. Accordingly, two types of fish culture are applied in the artificial waters of central east Africa — culture in reservoirs and culture in ponds.
A bas-relief found on an ancient Egyptian tomb shows Tilapia being fished out of an artificial pond, presumably a drainable one (frontispiece). This bas-relief is evidence that Tilapia culture was already practiced in Egypt about 2500 B.C. This is the oldest presentation of a fish culture pond in the world. It is also the oldest evidence of fish culture on the African continent. There are no records to suggest that, during the thousands of years which have since elapsed, fish culture has developed on the African continent until recent times.
With regard to other parts of the world, it is known that carp culture was widespread in China in 2000 B.C. and the ancient Romans introduced carp from Asia Minor into Greece and Italy. In central Europe, carp culture was already well established in the seventh century, and became widespread over the European continent at the beginning of the seventeenth century. In recent times first attempts to cultivate the Tilapia species were made in Kenya in 1924, which rightfully mark the turning point in Tilapia culture in modern Africa. The Congo followed the example in 1937. In central east Africa the first trials of fish pond culture were made in Zambia in 1942, to be followed by Rhodesia in 1950.
The development of pond culture in Africa is reflected in the records of the Anglo-Belgian Fisheries Conference held in Elizabeth-ville in 1949 and in the records of the fisheries symposia which followed, sponsored by the Commission for Technical Co-operation in Africa South of the Sahara through its Scientific Council. These symposia were held in 1952 in Entebbe, in 1956 in Brazzaville, and in 1960 in Lusaka.
Developments in fish culture in Africa during the last 20 years may be summarized as follows:
New research institutions have been established in some countries, while existing institutions have been enlarged.
Results so far have shown that crops of 3,000 pounds per acre per annum can be obtained from fish ponds with correct management and crops up to 6,000 pounds per acre per annum have been obtained. However, with unsophisticated rural pond management in central Africa, crops are more likely to be of the order of 1,000–1,500 pounds per acre per annum.
As a result of research work and publicity, fisheries are now recognized in many countries as a vital factor in national nutritional policy and more attention is being given to their development.
Results already achieved justify the intensification of fish culture, in order to reduce the deficiency of protein in the diet of the majority of African people today.
