Reproductive Characteristics of Odontobutis potamophila: Implications for Sustainable Fisheries Management

Odontobutis potamophila, a small benthic carnivorous fish endemic to the Yangtze River basin, holds considerable ecological and commercial value. However, overfishing and habitat degradation have led to a severe decline in its wild population. A lack of quantitative reproductive data has further hampered effective conservation and resource management. To address this, we conducted monthly sampling, collecting a total of 894 individuals from Nansi Lake between August 2017 and July 2018. By integrating gonadal histological staging, gonadosomatic index (GSI) analysis, logistic regression, and fecundity assessments, we provide a foundational understanding of the species' reproductive biology. The annual sex ratio was 1.06:1, with a temporary female bias in April (2.14:1) shifting due to male nest-guarding behavior. Both sexes reached maturity at one year and approximately 73.6 mm in length. Spawning occurred from March to June, peaking in May (GSI = 28.92%). Absolute fecundity ranged 2306 ± 1430 eggs and correlated positively with body size and age, while relative fecundity stabilized after age two. Individuals aged two years and older contributed over 80% of total egg production, reflecting a strategy of early maturation with high reproductive output at older ages. This study aims to systematically understand the reproductive biology of O. potamophila. These results support science-based measures such as Covering the entire window from gonadal maturation to fry dispersal, an annual fish ban established from March to June, a minimum catch size of 80 mm, and improved broodstock management for aquaculture and conservation efforts aimed at this and related benthic fishes in shallow lake ecosystems.