Courtship Behavior and Induced Spawning Dynamics of the Freshwater Shark, Wallago attu, in Captivity: Implications for Silurid Reproductive Strategies

The vulnerable catfish Wallago attu, a commercially important freshwater species in Southeast Asia, faces population decline due to habitat degradation and overfishing. This study is the first to document the courtship behavior and induced spawning of W. attu under captive conditions in circular spawning tanks. The hormonal induction was achieved using a combination of salmon gonadotropin-releasing hormone analogue and domperidone (0.5 mL kg−1 for females; 0.2 mL kg−1 for males). Males exhibited dominant courtship behavior, characterized by aggressive chasing and U-shaped body wrapping around the female’s abdomen for 5.15 ± 0.17 s, leading to synchronized gamete release. The latency period prior to the onset of spawning occurred within a time frame of 9–10 h following hormonal administration. The findings indicate that the removal of brooders following egg release resulted in a significantly higher rate of fertilization and hatching, with a percentage of 88.12 ± 0.26%, as compared to 67.78 ± 1.78% in tanks that contained brooders This observation suggests the presence of egg predation. Plastic strings functioned as effective artificial substrates, enhancing fertilization (86.42 ± 1.18%) and hatching (89.28 ± 0.80%) in comparison to aquatic weeds. The findings presented herein provide a foundation of information upon which the establishment of efficient captive breeding and hatchery protocols for W. attu can be based. Such protocols will in turn support the conservation of the species and the sustainable development of aquaculture.