Regulation of the fishing net mesh size is imperative in implementing the ethical code of responsible fisheries. The fishing net mesh size should be defined based on the biological conditions of regional or local fish populations. This study aimed to estimate fish size at first gonadal maturity and analyze the minimum net mesh size for the Indian mackerel fishing gear in North Maluku Province, Indonesia. The research was conducted from January to June 2022 around along the North Maluku waters. The fish length, body girth at first gonadal maturity and some aspects of mini purse seine fishing gear were addressed. The study results showed that the average total length at first gonadal maturity for the male fish was 24.27 cm and 24.01 cm for the female fish. Moreover, tThe study results recommended that the maximum fish length of 24.27 cm should be used to define the minimum net mesh size for the Indian mackerel fishing in the province. Further analysis assumed that the allowable minimum net mesh size for the mini purse seine main body and wings was 5.81 cm (2.27 inches), while a and for mesh size of more than or equal to 2.54 cm (≥ 1 inches) should be used for bunt part.