Ovarian and body responses of the African catfish (Clarias gariepinus) to human chorionic gonadotropin (Chorulon R) and carp pituitary suspension, used in a bioassay for estimating the gonadotropic activity of a crude carp powder preparation

Abstract Teleostean in vivo bioassays used for estimating the gonadotropic activity of fish pituitaries and gonadotropins are not standardized. Ovarian and body responses of the African catfish ( Clarias gariepinus ) to human chorionic gonadotropin (hCG) and a carp pituitary suspension (cPS) were used in a bioassay for estimating the gonadotropic activity of a crude carp powder preparation. The relationship between log-dose hCG and ovarian and body response was examined. Amongst the responses studied the stripped egg weight and stripping of ovary (wet weight of stripped eggs/wet weight of stripped eggs+wet weight of ovary after stripping × 100) are the most useful variables for a bioassay. The dose interval of 1103–1558 IU hCG and 0.724-1.025 mg cPS (per fish of 510 g, range ±50g) can be used for these responses in a bioassay. Whether or not the three-point parallel line assay provides a suitable model in the African catfish to perform a routine bioassay is not clear yet. Three fish per dose appears, in general, to be too small a number to get significant regression. In the case of significant regression, both for standard (hCG) and unknown preparation (cPS), tests for curvature and parallelism were carried out. For stripped egg weight and the stripping of ovary responses, the tests of curvature and parallelism were not significant, so the potency ratio was calculated for both variables and found to be 1 mg cPS equivalent to 1445 (1272–1613) IU hCG and 1 mg cPS equivalent to 1402 (1301–1496) IU hCG, respectively.