Reproductive Endocrinology and Hormonal Manipulation of Spawning in Heterobranchus longifilis in South West Nigeria

This study characterises the reproductive endocrine system of the vundu catfish Heterobranchus longifilis and evaluates the effectiveness of hormonal spawning induction protocols for aquaculture development in South West Nigeria. Heterobranchus longifilis is a large, fast-growing catfish with superior market value relative to Clarias gariepinus, but the lack of reliable controlled spawning protocols has prevented commercial scale-up of its production. Plasma concentrations of gonadotropins (FSH and LH), sex steroids (17-beta estradiol and testosterone), and gonadotropin-releasing hormone (GnRH) were determined by ELISA in wild-caught females across a gonadal development cycle established histologically. Five hormonal induction protocols were evaluated in triplicate: carp pituitary extract, LHRH analogue alone, LHRH plus domperidone, human chorionic gonadotropin (hCG), and a combined protocol. Ovulation rate, latency period, fertilisation rate, hatching rate, and 48-hour larval survival were compared. LH peaked sharply at ovulation onset and was the strongest predictor of spawning readiness. The LHRH analogue plus domperidone protocol produced the highest ovulation rate (86%), shortest latency (10.3 hours), and best fertilisation rate (81.3%). hCG alone produced variable results with longer latency and lower ovulation percentage. Plasma estradiol profiles peaked at final maturation, confirming the utility of estradiol as a readiness indicator. The study establishes baseline reproductive endocrinology data for Heterobranchus longifilis and delivers a validated spawning protocol directly applicable to commercial hatcheries in South West Nigeria. Keywords: reproductive endocrinology, Heterobranchus longifilis, spawning induction, aquaculture, hormonal manipulation.