A COMPARATIVE STUDY OF THE GONADO-SOMATIC INDEX (GSI) AND GONAD GROSS MORPHOLOGY OF AFRICAN CATFISH (Clarias gariepinus) FED UNICAL AQUA FEED AND COPPENS COMMERCIAL FEED

Abstract

A comparative study of the gonado-somatic index (GSI) and gonad gross morphology of African catfish, Clarias gariepinus fed Unical Aqua feed and Coppens commercial feed was carried out for six months in concrete tanks. Two triplicate groups of 50 postfingerlings with a mean bulk weight of 0.50 ± 0.02 kg were stocked in circular concrete tanks, area 16.63 m 2 labeled A 1 , A 2 , A 3 , B 1 , B 2 and B 3 . Fish in units A 1 , A 2 and A 3 were fed Coppens feed while fish in units B 1 , B 2 and B 3 were fed Unical Aqua feed twice daily at 3% of their body weights. Results obtained showed that mean gonad weight (99.03 ± 16.57 g) and the GSI (15.89 ± 2.10%) of female C. gariepinus fed Unical Aqua feed was not significantly different (P>0.05) from fish fed Coppens feed with mean gonad weight (91.80 ± 12.83 g) and the GSI (13.81 ± 2.49%). In male fish fed Unical Aqua feed, mean gonad weight (7.08 ± 1.17 g) and the GSI (1.16 ± 0.30%) were not significantly different (P>0.05) from male fish fed Coppens feed with mean gonad weight (6.77 ± 1.09 g) and the GSI (1.12 ± 0.32%). In female fish fed both feeds, there was a positive significant relationship between the GSI and total length, total weight and gonad weight. In male fish fed both feeds, there was also a positive non-significant (P>0.05) relationship between the GSI and total length, total weight and gonad. Food conversion efficiency (FCE) was insignificantly higher (P>0.05) in fish fed Coppens feed (50.94 ± 0.91%) than fish fed Unical Aqua feed (50.37 ± 1.29 %). Histology of ovaries and testes of fish fed the two experimental diets showed normal development and distribution of oocytes and interstitial cells. Proximate analysis of the dry matter showed that moisture content, fat content, crude fibre content, ash content, carbohydrate and caloric value (C/V) differed significantly among experimental groups (P 0.05). Physicochemical parameters were within acceptable range for fresh water fish culture. Based on these findings, Unical Aqua feed competed favorably with Coppens feed in terms of the GSI and gross gonad morphology of C. gariepinus and, on the basis of affordability, Unical Aqua feed is more economical and therefore recommended for fish farmers.