Pond culture is not a traditional farming practice in most parts of Africa. Introduced after the Second World War there was an initial spectacular aquaculture development with about 300,000 ponds being operational, mainly rearing Tilapia spp., in about 20 African countries by the end of the fifties (Meschkat, 1967). Since then fish culture has not made much further progress and has in many cases even declined resulting in the abandonment of fish ponds by discouraged farmers. According to the authors this failure has been attributed to:
· The harvesting of too many small stunted tilapia from over populated ponds because of the use of poor husbandry techniques.· The dependency on subsidized extension services and fingerling distribution centres.
· Misjudgement of the motivation of the rural fish farmers by policy makers, and the creation of the myth that the rural farmer will willingly take up fish farming for food security or as a source of protein for their family. This is most likely not the case, the primary motivation of the rural fish farmer generally being income generation.
· Failure to apply adequate resources (which may be naturally limiting) such as water and feed.
By the end of the sixties, a reorientation to increase aquaculture production was proposed that included:
· A modification of the farming technique for Tilapia spp. in which seed production and on-growing to marketable-sized fish are separated and the introduction of monosex tilapia culture (Pruginin, 1967 and Shell, 1968).· Identification of new, more suitable species for aquaculture development (Lemasson and Bard, 1968).
It was soon recognized that the African catfish Clarias gariepinus (Burchell 1822) was one of the most suitable species for aquaculture in Africa (CTFT, 1972; Micha, 1973; Pham, 1975; Jocque, 1975; Kelleher and Vincke, 1976; Richter, 1979; Hogendoorn, 1979) and since the seventies it has been considered to hold great promise for fish farming in Africa; the African catfish having a high growth rate, being very resistant to handling and stress, and being very well appreciated in a wide number of African countries.
The development of a reliable method for the production of C. gariepinus fingerlings was one of the priorities of aquaculture research in Africa (Anonymous, 1987a). Hormone-induced reproduction of the African catfish using deoxycorticosterone acetate, human chorionic gonadotropin and common carp pituitaries has been carried out successfully (Hogendoorn and Wieme, 1976; Hogendoorn and Vismans, 1980; Micha, 1976; Kelleher and Vincke, 1976; El Bolock, 1976).
Hogendoorn (1980) and Hogendoorn and Vismans, (1980) successfully developed an intensive farming system for African catfish fingerling production based on the use of Artemia salina nauplii and a commercial trout starter as feed. However the existence of technically feasible farming methods and manuals (Viveen et al., 1985) did not guarantee a successful implementation, as the impact of local socio-economic and technical conditions are more often than not always under-estimated (Anonymous, 1987b). The introduction of intensive rearing methods in the Central African Republic and the Ivory Coast encountered numerous technical and economic problems (Janssen, 1985a, 1985b and 1985c; de Graaf, 1989).
The main problem encountered with fingerling production in ponds was the poor and erratic fish survival rate; production varying from 0 to 60 fingerlings/m2/cycle (Micha, 1973, 1976; Hogendoorn, 1979; Hogendoorn and Wieme, 1976; Kelleher and Vincke, 1976). It has been suggested that the lack of appropriate feed and the presence of predators are the more likely causes of this mortality. In the late eighties a simple and reliable method was developed in the Republic of the Congo for the nursing of C. gariepinus within protected ponds (de Graaf et al., 1995) and this study indicated that competition for feed and cannibalism were the major factors affecting the pond nursing of C. gariepinus. The methodology as developed in the Republic of the Congo is now being used in many other African countries and an instruction video on this technique; “Anou is raising catfish” was produced by the FAO project (UNDP/FAO/PRC/88/007, Phase II) in the Republic of the Congo and can be obtained from the Nefisco Foundation, Amsterdam, the Netherlands (see Annex I).
The last twenty years has seen considerable gains in our knowledge concerning the reproduction and rearing of C. gariepinus, and in particular through the activities of FAO projects in the Central African Republic, the Republic of the Congo and Kenya; Centre Technique Forestier Tropical (CTFT) projects in the Ivory Coast; research programmes of the Department of Technology and Fisheries Science of the Rhodes University, South Africa and through basic research programmes carried out by the Department of Aquaculture and Inland Fisheries of the Wageningen University in the Netherlands and other Universities and Institutes throughout the world.
In the present paper an attempt is made to compile and update available knowledge concerning the rearing of C. gariepinus with particular emphasis on African conditions.
A number of the illustrations used in this paper have been presented before in the publication of Viveen et al., (1985) and permission given to use the illustrations in the present handbook is gratefully acknowledged.
Although more than 100 different species of the Genus Clarias have been described in Africa, a recent systematic revision based on morphological, anatomical and biographical studies has been carried out by Teugels (1982a, 1982b, 1984), who recognized 32 valid species. The large African species which are of interest for aquaculture belong to the subgenus Clarias. In earlier systematic studies on the large African catfish species Boulenger (1911) as well as David (1935) recognized five species within this subgenus. Both authors used morphological criteria such as form of vomerine teeth, ratio of vomerine to premaxillary teeth band and the number of gill rakers. The five species were:
· Clarias anguillarus
· Clarias senegalensis
· Clarias lazera
· Clarias mossambicus
· Clarias gariepinus
Natural geographical distribution
Clarias gariepinus, which is generally considered to be one of the most important tropical catfish species for aquaculture, has an almost Pan-African distribution, ranging from the Nile to West Africa and from Algeria to Southern Africa. They also occur in Asia Minor (Israel, Syria and South of Turkey). By contrast, Clarias anguillaris has a more restricted distribution and is found in Mauritania, in most West African basins and in the Nile (Figure 2). In general C. gariepinus lives in most river basins sympatrically with C. anguillaris.
