BETTY NYONGE1, CARSTEN SCHULZ1, FRANK KIRSCHBAUM2
1Humboldt-Universität zu Berlin, Department of Animal Science, Germany
2Leibniz - Institute of Freshwater Ecology and Inland Fisheries, Germany
About 50% of all known vertebrates are fishes. Of the estimated number of approximately 30 000 fishes nearly 50% comprize freshwater species, most of which are tropical freshwater fishes. Due to the high demand for animal protein in the tropics the aquaculture of tropical freshwater fishes has developed tremendously over the last decades. However, only a limited number of tropical freshwater species has been used up to now for aquaculture purposes. One reason for this is the lack of knowledge concerning biology and in particular reproduction in these species. The aim of our comparative study is to increase the knowledge on the reproduction - with preference on cyclical reproduction - of those taxa of tropical freshwater fishes comprising many economically important species.
In the framework of cyclical reproduction we study the influence of the variation of three environmental factors (decreasing conductivity, increasing water level, imitation of rain) on the maturation of gonads and finally spawning in the African knifefish Xenomystus nigri, on one silurid catfish, Kryptopterus bicirrhis, one schilbeid catfish, Eutropiellus vandenweyeri and two species of mochokid catfishes, Synodontis nigrita and S. nigriventris.
This paper discusses both aspects, a) the potential of tropical freshwater fishes for aquaculture development and b) ecophysiological research, with special emphasis to African fishes.
Keywords: Aquaculture development, cyclical reproduction, environmental factors, tropical freshwater fishes