Four extruded diets (Table 1) varying in protein and lipid
content were produced in pellets of 9 mm diameter by T.
Skretting Ltd, Stavanger, Norway. Each diet was randomly
assigned to three net pens for each fish group. All fish were handfed
to satiation four times per day, and the feed use was recorded
daily. The fish in each pen were weighed in bulk and counted on
days 0, 60 and 138, resulting in two growth periods of 60 and 78
days, periods 1 and 2, respectively. All fish were starved for 2
days before weighing and sampling. Dead fish were removed
from the pens daily and weighed