Author(s): PGWJ VAN OORDT
The reproductive cycle of male and female African catfish (Ctariasgariepinus) can be divided into a breeding period (May-August), a resting period (September-February) and a period of full gametogenesis (March-April). The pituitary gonadotropin (GTH) content and the ultrastructure of the gonadotropes largely parallel the cyclical changes in the gonads. The main characteristics of the pituitary GTH cycle are a prespawning GTH surge and a postspawning regression of the gonadotropes. These phenomena are suppressed when African catfish are kept under favourable husbandry conditions. Under such circumstances the pituitary stores large amounts of GTH and shows a limited, continuous secretion of the hormone, sufficient for a sustained gametogenesis and gonadal steroid production, but not for spontaneous spawning. Under such adequate fish culture conditions, ovulation can be induced and healthy larvae obtained at any time of year.