The Cichlid Fishes of Lake Malawi, Africa

Abstract of Publication

Morioka, S., and D. Sikawa. 2001. Feeding habit and development of feeding-related morphological characters in Oreochromis shiranus (Boulenger, 1896) larvae and juveniles in Malawi. Pp. 215-219 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.  

Stomach content, gut length, morphology of pharyngeal teeth and gill rakers of Oreochromis shiranus larvae and juveniles were investigated in order to elucidate the timing of feeding habit conversion, and the relationships between feeding habit and the feeding-related morphological characters. Stomach content showed that the feeding habit of fish drastically changed between 14-20 mm TL from zooplanktovorous to herbivorous (phytoplanktovorous). Pharyngeal plate and teeth were already ossified in the smallest fish of this study (9.95 mm TL) and teeth number increased as fish grew. Percentage length of gut ((gut length/TL) x 100 %) became more than 100 % when TL reached 15-20 mm, falling mostly under the size with feeding habit conversion. Gill rakers in 4th gill arch started appearing at 14 mm TL when the feeding habit started converting. Consequently, the conversion of feeding habit in Oreochromis shiranus started when the percentage intestine length became over 100 % and gill rakers in 4th gill started appearing, and pharyngeal teeth did not seem to relate directly with such feeding habit conversion.




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