2.3. Pen experiment
In the pond trial, each pen (432 m, 1 m water depth) was stocked with 20 O.
aureus fingerlings (c1.6 fish m 3) weighing between 9 and 12 g (10.28F1.31
(meanFSE)). Pens were made of nylon knotless mesh (mesh size: 2.54 cm). Each
treatment had four replicates (20 pens). Fish were fed following the feeding table of
Berzak (1992) two times daily (9:00 and 14:00 h) for 22 weeks. In the present study, daily
feeding levels varied from 10% to 2% of body weight during the course of the experiment.
In addition of the four treatments used (the same as in the aquaria experiment), a ‘‘no