Reproductive biology of rivulated peacock flounder (Pseudorhombus argus Weber, 1930) in Wallace Line, Spermonde Islands

In Wallace Line at Spermonde waters, Pseudorhombus argus is an ecologically and economically important flatfish species. For sustainable management and conservation, understanding its reproductive biology is essential. However, there is insufficient information on the reproductive components of P. argus in Spermonde waters. This study aimed to study the reproductive biology of P. argus in Spermonde waters, including sex ratio, gonad maturity stage, gonadosomatic index (GSI), and size at first sexual maturity. Samples were taken monthly from December 2023 to November 2024. Sex ratio, gonad maturity stage, gonad index, and size at first sexual maturity were all reproductive parameters considered. Based on sampling period, gonad maturity stage, and size class, P. argus was dominated by females. In addition, females had larger body sizes than males. Morphological differences in the gonad maturity stage indicated a balance between males and females. The highest GSI was recorded in April, indicating the beginning of the dry season. For females, sexual maturity occurs at 20.70 cm, and for males at 20.25 cm. However, the size of the first sexual maturity and the spawning season of P. argus differ from that of some other flatfish species. Such data are essential in developing a sustainable P. argus resource management plan. Key Words: flatfish, first maturity, gonadal index, sex-ratio, stage of maturity.