Comparative Evaluation of Tilapia (Oreochromis niloticus) Seed Quality in Pond and Recirculating Aquaculture Systems Under Variable Climatic and Water Quality Conditions

Climate variability poses increasing challenges to hatchery performance by altering water quality and larval physiology. This study compared the seed quality of Nile tilapia (Oreochromis niloticus) produced in traditional ponds and Recirculatory Aquaculture Systems (RAS) under fluctuating climatic and water-quality conditions. RAS maintained stable conditions (temperature 28.1–29.4°C; DO 6.8–7.4 mg L⁻¹; ammonia≈ 0 mg L⁻¹) compared with pond system (temperature 27.2–32.5°C; DO 5.8–7.0 mg L⁻¹; ammonia 0.02–0.07 mg L⁻¹). Larvae reared in RAS showed higher length gain (2.94±0.658% vs. 1.19±0.207%), greater weight gain (7.24±1.37% vs. 7.04±0.81%), and improved specific growth rate (0.23±0.032% day⁻¹). Fulton`s condition factor was also superior in RAS (mean KF 1.97–2.15) compared with pond system (1.45–1.65). Morphometric traits, including total and caudal length, were significantly higher in RAS (P<0.001). PCA showed that water-quality variables contributed 42.5% of total variance. GHRH gene expression was markedly upregulated in RAS, indicating enhanced physiological performance. Overall, the stable and controlled environment in RAS improved larval quality, developmental progression, and molecular growth regulation, highlighting its potential as a climate-resilient and sustainable hatchery strategy for tilapia seed production.