During the air transportation process, ¢sh are constantly
subjected to a series of stressors starting from
capture at farms to packaging for air transport, the adverse water quality and crowded and over-pressurized conditions during transport. It is well known that stress leads to osmoregulatory dysfunction (Harrell & Moline 1992; Weirich, Tomasso & Smith 1992)and causes fish mortality (Tomasso et al. 1980). The addition of salt to transport water has been found to be effective in reducing osmoregulatory disturbances
and fish mortality in several food fish species (Carneiro & Urbinati 2001). Similarly, when guppies were held in saline water for 40 h, their stress resistance increased with increasing salinity to 9%, which is close to isotonic conditions (Lim et al. 2000, Fig. 5).
Subsequent experiments showed that when guppies were packed in saline water of 1%,3% or 9% and
stocked in their respective salinities for recovery (with 30% daily dilution with freshwater) after ship-ment, all three treatments displayed a significantly
lower cumulative mortality than the control group at 7 days post shipment (Fig. 6).