The Scottish seine net used by fishermen in Majene waters generally has a low level of selectivity since it often catches small fish. Therefore, the Scottish seine net selectivity needs to be changed by changing the mesh size in the bag. This study used a modified Scottish seine net to analyze selectivity based on catches. The present investigation focused on analyzing the species composition and catch of a modified Scottish seine net based on the catchable size and the selectivity of a modified Scottish seine net based on catch. This research was conducted from July 2023 to January 2024, with a total of 78 trips. Observations were made by directly participating in fishing operations using modified Scottish seine net fishing gear, or what is commonly known as the experimental fishing method. The data collected were the number, species composition, and modified catch of each haul. The catch data collection technique was carried out by counting the number of catches contained in the main bag and outer bag, as well as weighing the total weight and measuring the total length of each type of fish caught. The results of the study detected nine types of fish catches: the shortfin scad (Decapterus macrosoma), the small mackarel tuna (Euthynnus sp < em>.), the bigeye scad (Selar crumenophthalmus), the rainbow runner (Eligatis bipinulata), the mackarel tuna (Euthynnus affinis), the skipjack tuna (Katsuwonus pelamis), the unicorn filefish (Aluterus monoceros), the golden trevally (Gnathanodon specious), and the fringescale sardinella (Sardinella fimbriata), with a total weight of 853,989kg. The sShortfin scad was the largest catch, with a total catch weighing of 680.177kg. The length of the shortfin scad at the interval between 19 and 25cm did not pass the main bag, so hence it can be interpreted that the modified seine is selective for the shortfin scad. In addition, F50 (50%) was obtained with a length of 13.98cm.