Effect of Photoperiod Manipulation on Spawning Induction in Catfish Broodstock in Cross River State

Manipulating environmental cues to improve the reliability of induced spawning in African catfish is a priority for commercial hatchery operators seeking consistent fingerling production. This study investigates the effect of photoperiod manipulation on spawning response and egg quality in Clarias gariepinus broodstock held at a hatchery in Calabar, Cross River State, South South Nigeria. Broodstock females were assigned to three photoperiod treatments, specifically natural light (12 hours light:12 hours dark), extended light (16 hours light:8 hours dark), and reduced light (8 hours light:16 hours dark), in light-controlled tanks over a 21-day conditioning period before hormonal induction using ovaprim. Spawning response, latency period, fertilisation rate, hatching rate, and larval deformity rate were recorded for each treatment group. Results showed that females conditioned under the 16-hour light treatment exhibited the highest ovulation response (88%) and shortest latency period to spawning. Fertilisation rate and hatching rate were also significantly higher in the extended photoperiod group compared to both the control and reduced light groups. Larval deformity rates were lowest in the extended photoperiod treatment. The study concludes that extended photoperiod conditioning for 21 days prior to hormonal induction improves reproductive performance in African catfish broodstock and recommends its integration into hatchery management protocols at Cross River State commercial catfish hatcheries seeking consistent and high-quality fingerling output.

Keywords: photoperiod, spawning induction, Clarias gariepinus, hatchery management, Cross River State