Turbot larvae will be reared under standard laboratory conditions based on Brachionus/Artemia in Vigo, Spain and under extensive conditions in Hirtshals, Denmark. (Under laboratory conditions it is possible to handle high numbers of larvae, and starvation is easily induced. However, laboratory reared larvae are usually in a poorer health condition with slower growth and high mortality. Extensively produced larvae have high growth rates and low mortality. However, production capacity is limited, and transfer to starvation may affect the larvae). Larvae with an age of 3 days, (end of yolk sac stage), 10 days (critical age in rearing) and 17 days (end of critical age) are deprived of food. At selected time intervals after onset of starvation, samples of larvae are analysed and compared to fed larvae. The parameters considered for the comparative study will be the following: length, dry weight, growth rate, condition factor, mortality, intestinal histology, lipids, vitamin C, RNA/DNA, CHN, amino acid profile.