The Cichlid Fishes of Lake Malawi, Africa

Abstract of Publication

Kamanga, L.J., E. Kaunda, J.P. Mtimuni, A.O. Maluwa, and W.M. Mfitilodze. 2001. Effect of temperature on oocyte development of Oreochromis karongae (TREWAVAS). Pp. 233-241 in: Weyl, O.L.F., and M.V. Weyl (Eds). Proceedings of the Lake Malawi Fisheries Management Symposium, 4th-9th June 2001, Capital Hotel, Lilongwe. National Aquatic Resource Management Programme (NARMAP), Monkey Bay. 272 pp.  

Oreochromis karongae (Trewavas) is one of the indigenous Tilapias that exhibit favorable traits for aquaculture in Malawi. However, fingerling production has been a problem. An experiment was therefore carried out to find the effect of temperature on oocyte development of the fish. Female O. karongae were reared under two temperature regimes, room (20.3 ± 0.8°C) and raised (26.5 ± 0.5°C) for 90 days while changes in gonadosomatic index (GSI) and oocyte developmental stages were followed every 45 days. Fish samples from the pond in which experimental fish were collected were used for comparison. Results showed that raising temperature to 26.5 ± 0.5°C significantly enhanced oocyte development. Higher GSI (p<0.05) were obtained after 45 and 90 days in fish cultured in raised temperature (0.817 ± 0.657 and 1.133 ± 0.471 %, respectively) than those from room temperature (0.057 ± 0.027 and 0.367 ± 0.045 %, respectively). GSI of fish samples from the pond were not different from that of fish from room temperature. Relative frequency of mature oocytes was higher (p<0.05) in fish from raised temperature (60.42 ± 3.63 %) than in fish from room temperature (1.76 ± 0.84 %) and pond (2.43 ± 1.38 %) after 45 days. After 90 days, the frequency of mature oocytes in fish from raised temperature was not different from that in fish from the pond (8.68 ± 2.40 and 10.99 ± 3.41 % respectively). Fish from room temperature had a low (p<0.05) frequency of mature oocytes (3.12 ± 2.03 %). The results suggest that O. karongae has the potential to spawn throughout the year if temperature is manipulated.




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