Effects of Stocking Density, Size, and External Stress on Growth and Welfare of African Catfish (Clarias gariepinus Burchell, 1822) in a Commercial RAS

The effects of semi-intensive (100 kg m−3), intensive (200 and super-intensive (400 m−3) stocking densities on the growth welfare African catfish (Clarias gariepinus) were investigated under commercial production conditions. Plasma cortisol, glucose, selected transcripts following a stress challenge, lactate, as well skin lesions, analyzed at regular intervals (from 12 g juveniles to 1.5–2.0 kg). fish grew well, but after 23 weeks, semi-intensively stocked had mean final weight 1830.5 g, significantly higher than super-intensively with 1615.4 considerably intensively 1664.8 (p > 0.05). Cortisol glucose responses differed between stressed unstressed fish, not treatment groups. An unforeseen external stressor (nearby demolition noise) caused among all groups, was similarly coped with. Mortality ranged 3.8–9.2%. In juveniles, lesions reduced or densities, least in outgrown fish. Expression profiles 22 genes compared spleen densities. transcript concentrations most remained unchanged, except for slc39a8 mtf1, which downregulated We demonstrated that performance depend age density, also reacting noise. This supports farm management optimize during grow-out RAS suggests avoiding stress.