2.3. Fish sampling and chemical analyses
All fishwere individuallyweighed at the start of the experiment and group-weighed by tank every fourweeks thereafter. Fishwere fasted on the morning of weighing days. Four fish from the initial stock and one fish from each tank at the end of the experiment were sampled and stored frozen at −80 °C for subsequent whole-body composition analysis.
Another fish from each tank at the end of the experiment was dissected to remove liver, fillet and intestinal samples.
The liver weight was recorded and used to calculate the hepatosomatic index.
Fillets were frozen at −80 °C until analysis. Small pieces (b0.5 cm) of the distal intestine were sampled for histological analysis of gastrointestinal morphology