Some aspects of reproduction in ricefield eel, Monopterus albus (Zuiew), maintained in a concrete tank
1997
Harmin, S.A. | Tang, C.H. | M.A. Ambak | U. Salleh
A study on some aspects of gonadal development and correlation of the sexual stages to body length of the ricefield eel, Monopterus albus (Zuiew), was undertaken between September 1992 and January 1993. Wild-caught eels were maintained in a concrete tank of 4-ton capacity in the hatchery and fed with 45% protein diet at 3% body weight/day. A sample of eels (n=8) from the tank was collected every two weeks. The majority of the eels used in the study were within 500-700 mm in total length and of 100-500 g body weight. Identification of the development of the gonads was conducted histologically. Among the 56 eels studied, 68% were females, 28% intersexes and 4% males. Generally, males were bigger in size (greater than 700mm) while females and intersexes were 400-750 and 400-850 mm, respectively. None of the females reached maturity stage and tertiary yolk granule was the most advanced stage of the oocyte development. The biggest oocyte was 1.08 mm. Frequency distribution of the oocyte diameter did not show a clear migration towards maturity. Other reproductive indicators such as gonadosomatic index, hepatosomatic index, dry matter and condition factor also showed no significant changes throughout the study. The results of the present study could be used for developing techniques to induce maturation of the gonads either through hormone manipulation or broodstock nutrition. This species can be used as a model to study egg quality in teleosts.
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