Understanding the relationship between production management and protandrous hermaphroditism in farmed Asian seabass (Lates calcarifer Bloch 1790) is vital for optimising aquaculture efficiency. This study evaluated the growth performance and gonadal development of Asian seabass (n = 112) across six open and semi-closed small-scale farms in Peninsular Malaysia. With the exception of one farm population that displayed negative allometric growth (𝑏𝑏 < 3 ), fish growth was isometric (𝑏𝑏 = 3 ) across the remaining groups. Non-parametric Mann-Whitney U tests revealed that semi-closed systems achieved significantly higher performance metrics than open configurations, where the relative condition factor (K) was significantly elevated (median 1.30 vs. 1.18; W = 172, p < 0.001), as was the Specific Growth Rate (SGR, median 1.01 vs. 0.99 % day-1; W = 279.5, p = 0.046). Multi-model information-theoretic selection (AICc) confirmed that farming practice models that combine enclosure method and water-source environment offered the highest predictive support (model weight, Wt = 76%), outperforming models based on broad system (semi-closed vs. open) configurations alone. Histologically, ordinal logistic regression models revealed that water salinity environmentally drives sex reversal in the farmed fish. Holding total length constant, fish reared in low-salinity environments (≤ 25 ppt) exhibited 9.1 times higher odds of occupying advanced gonadal stages compared to high-salinity cohorts (> 25 ppt), significantly compressing both male-peak and female-transition size thresholds. Ultimately, these findings demonstrate that while semi-closed infrastructure accelerates daily growth velocity, small-scale farmers must prioritise matching specific culture methods to environmental salinity profiles to manage growth and sex reversal timelines effectively.