In order to investigate the stress responses during crowding and subsequent recovery
at different concentrations of NaCl, other groups of fish were also transferred upon
arrival to indoor tanks at 50 fishrm3 and allowed to acclimate for 1 week in running
water. Salinity in these tanks was kept at 2–3 ppt NaCl during the first day and then
diluted within the next 24 h to 0 ppt. After 1 week, fish were netted and crowded in
smaller tanks with water at 0 ŽYoshida Stock. and 5 ppt NaCl ŽYasuda Stock., at a
density of 100 fishrm3 Žsame as during transport.. The water temperature during
crowding was 20.6"0.68C, the pH was 7.2"0.2 and the dissolved oxygen was
7.1"0.1 mgrl. After 4 h, the fish were returned to the original tanks and rearing
density but the tanks contained water at 0, 5 and 20 ppt NaCl. Fish in these tanks were
maintained as for fish recovering after transport