The resting metabolic rate (MO 2rest ) of juvenile Nile tilapia (Oreochromis niloticus) decreased from 264.5 to 189.4 mg O 2 kg À1 h À1 after one week of starvation and the maximum post-exercise oxygen consumption (MO 2peak ) decreased from 1032.5 to 647.4 mg O 2 kg À1 h À1 . MO 2rest and MO 2peak decreased further to 166.5 and 463.3 mg O 2 kg À1 h À1 respectively after six weeks of starvation. Furthermore, the duration of the excess post-exercise oxygen consumption (EPOC) decreased from 113.3 to 56.3 min, and the magnitude of EPOC decreased from 276.8 to 100.2 mg O 2 kg À1 . We conclude that tilapia are very sensitive to food shortage and rapidly reduce their energy expenditure. The decreased metabolic scope and EPOC imply that both aerobic and anaerobic metabolic capacities are reduced in starved tilapia, possibly as a result of glycogen depletion. We suggest that food deprivation should not exceed one week when Nile tilapia are used as experimental fish.

The effect of incubation and rearing temperature on muscle development and swimming endurance under a high-intensity swimming test was investigated in juvenile Chinook salmon (Oncorhynchus tshawytscha) in a hatchery experiment. After controlling for the effects of fork length (L F) and parental identity, times to fatigue of fish were higher when fish were incubated or reared at warmer temperatures. Significant differences among combinations of pre-and post-emergence temperatures conformed to 15-15 C > 15-9 C > 9-9 C > 7-9 C > 7-7 C in 2011 when swimming tests were conducted at 300 accumulated temperature units post-emergence and 15-9 C > (7-9 C = 7-7 C) in 2012 when swimming tests were conducted at an L F of c. 40 mm. The combination of pre-and post-emergence temperatures also affected the number and size of muscle fibres, with differences among temperature treatments in mean fibre cross-sectional area persisting after controlling for L F and parental effects. Nonetheless, neither fibre number nor fibre size accounted for significant variation in swimming endurance. Thus, thermal carryover effects on swimming endurance were not mediated by thermal imprinting of muscle structure. This is the first study to test how temperature, body size and muscle structure interact to affect swimming endurance during early development in salmon.