Abstract: LED fishing lamps are one of the important fishing equipment for light-induced fisheries such as Pacific saury (Cololabis saira). The light configuration and illuminance distribution of these lamps directly impact fishing yield and catch efficiency. To optimize the lamp configuration, based on commercial LED fish-attracting lamps used for C. saira, we used TracePro software to establish a luminous model of the lamps for calculating underwater illuminance distribution. Then we validated the reliability of this model by comparing its predicted illuminance distribution with observed values obtained from tank tests. Based on the stable stay illuminance range for C, saira, the region enclosed by the 100 to 200 lx contour lines was defined as the usable water volume. The effective area of each water layer was calculated separately, and the prismatic volume formula was used to estimate the volume of the effective water. The results indicate that: 1) At inclination angles of 45°, 60°, and 75°, there was no significant difference (p>0.05) between the observed values from tank tests and the fitted values from TracePro, demonstrating that the luminous model accurately reflects real-world conditions. 2) At the same inclination angle, as water depth increased, the effective water body area initially expanded and then contracted. 3) At inclination angles of 30°, 45°, 60°, and 75°, the effective water depths were 2.4, 2.1, 1.8 and 1.4 m, respectively. 4) Within the 0° to 90°inclination angle range, the effective water body volume first increased and then decreased, reaching its maximum at angles between 30°and 40°.