Growth Pattern and Condition in the Mudskipper <i>Scartelaos histophorus</i> in the Mekong Delta

Studies of the length-weight relationship (LWR) and condition factor (CF) in fish are abundant but often descriptive; yet, most studies overlook how intrinsic and extrinsic drivers structure these metrics. Here, this study tested whether the growth exponent (<i>b</i>) varies across sex, season, and ecological region, and whether CF is elevated in females and before spawning. Over the course of a complete annual cycle, a total of 1436 individuals were collected from four mudflat sites, measured for total length (TL) and weight (W), and analyzed using log10-linear regressions of LWR and CF, along with appropriate parametric or non-parametric tests under false discovery rate control. The TL strongly predicted W (<i>r</i> ² = 0.87) with <i>b</i> = 2.46 ± 0.02 SE, (< 3; <i>p</i> < 0.001), indicating negative allometry. Females showed a larger size and higher <i>b</i> value (2.52) than males (2.41). The dry season yielded a higher <i>b</i> value than the wet season, and southern sites showed a non-significant trend towards a higher <i>b</i> value than northern sites. Mean CF was 1.01 ± 0.01 SE, elevated in females (1.09 vs. 0.98) and in the dry season (1.04 vs. 0.99), while monthly fluctuations (0.89-1.08) tracked feeding and reproduction but showed no regional differences. Overall, <i>S. histophorus</i> exhibits consistently negative allometric growth, with systematic variation in <i>b</i> and CF across sex and season. These findings provide hypothesis-driven baselines for monitoring semi-terrestrial gobies and highlight the importance of considering life-history and hydrological context when applying LWR/CF in ecological and evolutionary research and management.