A comparative study of gonadosomatic index (GSI) and gonad gross morphology of the 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 post fingerlings with a mean bulk weight of 0.50 ± 0.02 kg were stocked in circular concrete tanks, area 16.63 m2 labeled A1, A2, A3, B1, B2 and B3. Fish in units A1, A2 and A3 were fed Coppens feed while fish in units B1, B2 and B3 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. gariepi nus 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 in significantly 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), while significant difference for crude protein content was not found (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.