This update of the document previously published in 1980 includes new data on pathogens previously not known to harm African fish (viruses, bacteria, fungi), and parasites earlier disregarded by fish pathologists, which are now being recognised as important pathogens of fish (Coccidia, Dermocystidium-like organisms, blood flukes), including the African species. the update also provides new data and interpretations on the life histories and developmental biology of pathogens and parasites which were previously little known or regarded as enigmatic (example Myxosporeans). Also communicated in this text are recent scientific findings on the general and the specific, acquired-type, defence responses activated by fish against prokaryotic and eukaryotic pathogen infections and the potential implementation of these immunological findings for the development of vaccines.
The review of diseases and infections of African fish has been expanded to include information from geographical regions outside Africa which could be relevant to the context of African fish and the warm-water environment. This information incorporates data from Israel, located at the north eastern end of the African continent, where African fish (cichlids and Clarias lazera) occur naturally, and are farmed in polyculture with European and Asian carp and grey mullets in warm water ponds (Sarig, 1989).
Also incorporated is information concerning tilapia farmed in the Southern USA and East Asia, as well as Asian carp and catfish farmed in tropical Asia. The information from the fast developing, both extensive and intensive, aquaculture of African tilapia in the Far East, particularly on viral and bacterial diseases, is of particular importance as first-hand knowledge, as well as for the prediction of diseases likely to affect future developing aquaculture in tropical Africa.
Of special interest are the pathogens carried by tropical ornamental fish. Inevitably, all these would appear to be of relevance to fish farming practices in Africa. Growing trade and commercial rearing of these fish is an increasing source for concern: there is a growing number of reported epizooites following introductions of exotic tropical ornamental fish of diverse origins into commercial systems.
New information has been obtained, since the preparation of the previous document (1979 – 1980), from a number of sources. These include; comprehensive formerly published reports on diseases relevant to African fish, Roberts & Sommerville (1982), Paperna et al. (1984) and Michel (1989), reviews on cichlids (tilapia) and a report issued by the University of Stirling (Balarin & Hutton, 1979). In addition, comprehensive reports on fish parasites include; a check list on parasites of fish in Southern Africa (Van As & Basson, 1984) and a report by Douellou (1992a,b) on infections in L. Kariba fish. Three publications deal with “winter” diseases of cichlid fish living or farmed outside tropical Africa (Paperna, 1984; Oldewage & Van As, 1987; Lightner et al., 1988). Further important sources of information include several, as yet un-published, university degree theses, dealing with individual groups or taxa of parasites; helminths of northern Transvaal fish (Mashego, 1982), metacercarial infections (Yekutiel, 1985; Farstey, 1986; Finkelman, 1988). Data from other degree theses published in the current scientific literature, in the interim period, are quoted where relevant in the text.
REFERENCES
Balarin, J.D. & Hutton, J.P., 1979. Tilapia. A guide to their biology and culture in Africa. Unit of Aquatic Pathobiology, University of Stirling, Scotland. 174 p.
Douellou, L., 1992a. A survey of fish parasites in Lake Kariba, Zimbabwe (1989–1992), Final Report. ULKRS [University of Zimbabwe Lake Kariba Research Station] Bulletin, 1/92. 71 p.
Douellou, L., 1992b. Parasites of Oreochromis (Oreochromis) mortimeri (Trewavas, 1966) and Tilapia rendali rendali (Boulanger, 1836) in Lake Kariba, Zimbabwe. University of Zimbabwe Lake Kariba Research Station Bull., 2 (Proc. of seminar series): 14–31.
Farstey, V., 1986. Centrocestus sp. (Heterophyidae) and other trematode infections of the snail Melanoides tuberculata (Muller, 1774) and cichlid fish in Lake Kinneret. MSc Thesis, Hebrew University of Jerusalem (Hebrew text, English summary).
Finkelman, S., 1988. Infections of Clinostomatidea in the Sea of Galilee fish. MSc Thesis, Faculty of Agriculture, Hebrew University of Jerusalem (Hebrew text, English summary).
Lightner, D., Redman, R., Mahoney, L, Dickerson, G. & Fitzsimmons, K., 1988. Major diseases encountered in controlled environment culture of tilapias in freshwater and brackish water over a three year period in Arizona. In: Pullin, R.S.V., Bukaswan, T., Tonguthai, K. & Maclean, J.L. (eds.) The Second International Symposium on Tilapia in Aquaculture. ICLARM Manila, Philippines, pp. 111–116.
Mashego, S.N., 1982. A seasonal investigation of the helminth parasites of Barbus species in water bodies in Lebowa and Venda, South Africa. PhD Thesis, University of the North, Sovenga, south Africa. 191 pp.
Michel, C., 1989. Pathology of tilapias. Aquat. Living Resour. 2: 117–126.
Oldewage, W.H. & Van As, J.G., 1987. Parasites and winter mortalities of Oreochromis mossambica. S. Afr. J. Wildl. Res., 17: 7–12.
Paperna, I., 1984. Winter diseases of cultured tilapia. In: Acuigrup (ed.) Fish Diseases. Fourth COPRAQ session. Editora ATP Madrid (Espanha) pp. 139–147.
Paperna I., Van As, J.G. & Basson, L., 1984. Review of diseases affecting cultured cichlids. In: Fishelson, L. & Yaron, Z. (eds.) Internat. Symp. on Tilapia Aquaculture, Tel Aviv University Press. pp. 174–184.
Roberts, R.J. & Sommerville, C., 1982. Diseases of tilapias. In: Pullin, R.S.V. & Lowe-McConnell, R.H. (eds.) The Biology and Culture of Tilapias. ICLARM Conference Proceedings, 7, Manila, Philippines. pp. 247–263.
Sarig, S., 1989. Introduction and state of art of aquaculture. In: Shilo, M. & Sarig, S. Fish culture in warm water systems: problems and trends. CRC Press, 1–19.
Van As, J.G. & Basson, L., 1984. Checklist of freshwater fish parasites from southern Africa. S. Afr. J. Wildl., 14: 49–61.
Yekutiel, D., 1985. Metacercaria infections of cichlid fry in Lake Kinneret. MSc Thesis, Hebrew University of Jerusalem (Hebrew text, English summary).
