The growing public interest in catfish farming has resulted in an increased demand for catfish fingerlings. This trend has led many individuals to engage in the trade of catfish fingerlings, either as a primary source of income through the establishment of fisheries groups or as a supplementary means of generating additional revenue. This study aims to investigate the implementation of the catfish fingerling trading system based on volume measurement from the perspectives of Islamic law and positive law. Utilizing a qualitative research approach, primary data were collected through interviews and documentation. The primary data sources include informants from fisheries business groups and individuals involved in the trade of catfish fingerlings using the volume-based measurement system. The findings reveal that the volume measurement system is employed to simplify the calculation process, although the initial reference measurement is not consistently aligned with subsequent measurements. Nonetheless, both parties agree to add an additional volume as compensation for potential mortality of the fingerlings. From the perspective of Islamic law, the catfish fingerling trading practices in Gunung Sembung Village, Pegaden Subdistrict, Subang Regency, fulfill the essential elements and conditions required for lawful transactions under Islamic law and are deemed valid according to positive law, as they conform to existing legal regulations.