During the spawning season, seabream often exhibit reduced or arrested somatic growth, a phenomenon that is particularly relevant in protandrous hermaphroditic species that undergo male-to-female sex reversal as body size increases. Under these conditions, maintaining growth and physiological condition is critical for broodstock performance. The present study aimed to evaluate the interactive effects of dietary lipid source and vitamin E supplementation on growth and nutritional performance of male seabream broodstock during the spawning season. A total of 180 male seabream (initial mean weight: 338.61 ± 1.94 g) were randomly distributed among 18 concrete tanks (4-ton capacity) and assigned to six dietary treatments in a 3 × 2 factorial design. Experimental diets contained three levels of fish oil replacement with soybean oil (0, 50, and 100%) and two levels of vitamin E supplementation (0 and 2.5 g kg⁻¹ diet) and were fed for 8 weeks. The results showed that diets enriched with long-chain polyunsaturated fatty acids (LC-PUFAs), particularly n-3 fatty acids, in combination with vitamin E significantly enhanced growth performance indicators, including weight gain, specific growth rate, condition factor, feed conversion ratio, lipid efficiency ratio, and total feed intake (p < 0.05). Visceral indices such as the gonadosomatic index (GSI) and hepatosomatic index (HSI) were also significantly higher in these treatments, reflecting improved gonadal development and hepatic metabolic status. In contrast, no significant differences were observed in visceral fat index or relative gut length, indicating that dietary lipids and vitamin E were preferentially allocated to somatic growth and reproductive processes rather than visceral fat deposition or intestinal growth. Overall, the findings demonstrate that dietary formulations rich in LC-PUFAs—especially DHA and EPA—combined with vitamin E supplementation markedly improve growth efficiency, feed utilization, and reproductive-related visceral indices in male seabream broodstock during the spawning season. These results highlight the importance of targeted lipid and antioxidant nutrition in broodstock diet formulation to optimize growth and physiological performance.