Reproduction and growth of the African sharptooth catfish, Clarias gariepinus, under controlled conditions at eco fish farm in Hardap region, Namibia

Abstract

Abstract by author:

Hormone-induced breeding of the African sharptooth catfish Clarias gariepinus, a Clariidae species farmed at the Eco Fish Farm, Hardap, was carried out using the C. gariepinus pituitary gland homogenate. The growth of post larvae and juveniles was quantified. After administering the pituitary hormone injection to both males and females, spawning of sharptooth catfish occurred within 24 [hours] and about 382 950 eggs were obtained. The sexual maturity of males and females was synchronized. Eggs started hatching after 30 hours and the process was completed after approximately 100 hours (four days), producing 10, 650 eggs. The percentage of hatching of 2. 8 percent was considered low compared to average literature values of 10 percent. Hatching needs to be improved. Absorption of yolk sac was observed on the second day. Exogenic feeding commenced 2 days after hatching and frequency of feeding was three times a day using Atermia nauplii as starter feed with DHA protein being as a supplementary. Length and weight data were collected once a month from April to August, 2004. The data was computed and analyzed using Microsoft Office Excel (Mecer PC). The growth function, SGR percent (increase in relative growth per day) was found more appropriate than VBGF model, because the latter model does not apply to very small fish. The negative values obtained during early (post-larvae) growth may be attributed to non compliance with normal growth models employed to estimate growth increment. Strong correlations were obtained between length and weight, length and time as well as weight and time relationships