Increased stocking density is a chronic stressor that can lead to decreases or increases in
the growth of African catfish (Kaiser et al., 1995; Hossain et al., 1998; van de
Nieuwegiessen et al., 2008). In this study, growth of African catfish decreased as the
stocking density increased. High stocking density can affect fish growth through the
combined effects of crowding stress and water quality deterioration in recirculating
systems (Santos et al., 2010). Here, 150% daily water exchange was insufficient to
prevent deterioration of the water quality.