Temperature affects the early allometric growth pattern of Coreius guichenoti

Coreius guichenoti, an endemic and economically important fish species in the upper Yangtze River, exhibits early growth stages that are highly sensitive to fluctuations in water temperature. Recent cascade dam constructions have altered the hydrological regime of the Yangtze River, exacerbating thermal stratification and potentially threatening natural reproduction and population sustainability. To investigate the effects of temperature on early growth and morphological development of C. guichenoti, this study simulated five temperature conditions (17.5℃, 20.0℃, 22.5℃, 25.0℃, and 27.5℃) in a controlled laboratory setting, systematically analyzing growth patterns and allometric developmental trajectories of morphological organs in individuals aged 0–30 days post-hatching. Results revealed that temperature significantly regulates growth rates and allometric growth strategies. Low-moderate temperatures (17.5–22.5℃) induced gradual declines in growth rates, whereas high-temperatures (25.0–27.5℃) enhanced or stabilized growth rates, with the highest post-inflection growth rate (0.92 mm/day) and the largest asymptotic length (87.83 mm) observed at 25.0℃. Allometric analysis showed that head traits (head length and eye diameter) exhibited positive allometry under low temperatures (b>1), transitioning to negative or isometric growth at temperatures ≥ 25.0℃. Trunk and tail allometric patterns shifted from “survival-oriented” to “growth-oriented” strategies with increasing temperatures. Comprehensive analysis identified 22.5–25.0℃ as the optimal thermal range for early development, characterized by high growth rates, delayed inflection points, and balanced energy allocation between survival and growth. These findings provide a theoretical basis for conservation strategies and hatchery temperature management of C. guichenoti in the Yangtze River, and offer insights for mitigating malformation risks in high-temperature aquaculture.