Brown sole Pleuronectes herzensteini were reared experimentally to the juvenile stage to determine the influence of rearing temperature and the timing of feeding Artemia Artemia salina nauplii on the occurrence of morphological abnormalities. In one series of experiments, sole larvae were reared at different temperatures (6-24°C) with the same feeding schedules. Rearing temperatures higher than 18°C reduced the appearance of morphological abnormalities. In the second series of experiments, the initial feeding of addition of Artemia nauplii was varied among experimental groups at constant temperature (15°C). The first group to receive Artemia nauplii were at the 4.5-8.0mmTL of sole larvae and the last group did not receive them until metamorphosis. Early feeding of Artemia nauplii reduced morphological abnormalities. Subsequently, mass production techniques were modified to determine if a combination of early feeding of Artemia nauplii to sole larvae (5.5mmTL) and high rearing temperature (18°C) could reduce morphological abnormalities in mass production tanks (20-50m3). These modifications resulted in the highest percentage (56-80%) of normal fish observed during the eleven years of mass seed production of brown sole.
