The objective of this study was to assess the impact of di erent dietary Trp concentrations on
the stress and metabolism response of juvenile Senegalese soles (Solea senegalensis). Fish (38.1 1.9 g)
were fed di erent Trp-enriched feeds (0%, 1% and 2% Trp added) for two and eight days, and later
exposed to air stress for three min. Samples were taken pre- and 1 h post-stress (condition). Plasma
cortisol, lactate, glucose and proteins were significantly a ected by the sampling time, showing higher
values at 1 h post-stress. Trp concentration in food also had significant e ects on lactate and glucose
levels. However, the feeding period did not a ect these parameters. Post-stress values were higher
than in the pre-stress condition for every plasma parameter, except for lactate in two days and 1% Trp
treatment. Nevertheless, cortisol, glucose and lactate did not vary significantly between pre- and
post-stress samplings in fish fed the 1% Trp-enriched diet for two days. The lack of variability in
cortisol response was also due to the high pre-stress value, significantly superior to pre-stress control.
The exposure time to Trp feeding did not significantly a ect any enzyme activity; however, Trp added
and condition influenced protein-related enzyme activities. In spite of decreasing stress markers,
Trp-enriched diets altered the protein metabolism