Effects of temperature on somatic growth, gastric pepsin activity, and endocrine dynamics in orangefin labeo (Labeo calbasu)

This study investigated the effects of varying water temperatures on somatic growth, digestive enzyme activity, and endocrine responses in orangefin labeo (Labeo calbasu), a commercially important freshwater fish species. The experiment was performed in triplicate using 100 L glass aquaria at four temperature levels: 22, 26, 30, and 34°C. Over a 60-day experimental period, growth performance, pepsin activity, and hormonal dynamics were analyzed to identify optimal thermal conditions for aquaculture. Results demonstrated that 30°C was the most favorable temperature, yielding the highest specific growth rate (SGR: 0.45±0.05% day–1, n = 10), weight gain (3.07±0.70 g, n = 10), and length increase (1.29±0.57 cm, n = 10). In comparison, 22°C exhibited the lowest growth metrics (one-way ANOVA: p < 0.05). A thermal threshold for enzymatic efficiency was shown by significantly lower pepsin activity at both lower (22°C) and higher (34°C) temperatures, whereas digestive pepsin activity peaked at 30°C (8.34±0.71 U37 mg protein–1). Endocrine analysis revealed that the hormonal dynamics also temperature dependent. Reproductive hormones-follicle-stimulating hormone (FSH: 1.45±0.10 mIU mL⁻¹), luteinizing hormone (LH: 1.61±0.04 mIU mL⁻¹), testosterone (1.50±0.01 ng dL⁻¹), and estradiol-17β (E2) reached peak at 30°C which were higher than in other treatments (p < 0.05). Overall L. calbasu exhibited optimal growth, digestive efficiency, and reproductive performance within a narrow temperature range of 26–30°C (p < 0.05). These findings underscore the species’ sensitivity to temperature variation and highlight the importance of maintaining stable thermal conditions to ensure sustainable productivity and conservation in aquaculture.

Journal of Fisheries

Journal of Fisheries

14

2311-3111

N/A

2

10