Food delivery started at 36 hah. From this moment on, newly hatched brine shrimp (Artemia) nauplii were delivered every 3 h (eight times per day). Brine shrimp naupliiwere produced twice a day (20-h incubation of cysts at 29 °C in brackish water [25 g NaCl L−1]) and maintained in brackish water in a refrigerator (4–6 °C) during the 12 h following hatching. The concentration of brine shrimp nauplii was determined by volumetric counts (mean of three replicates) in 1- mL samples that were collected with a pipette. At each meal, an identical volume of brackish water was collected, brine shrimp nauplii were rinsed and placed in fresh water from the recirculating system a few minutes before distribution to the experimental tanks, in order to
minimise the amount of salt that was transferred to the rearing environment. At the time of food delivery, water flow in the tanks was stopped for 30 min in order to maintain the prey density as homogeneous as possible throughout the tank (i.e. otherwise brine shrimp nauplii tend to drift and concentrate near the exit of the tank).
This 30-min period was adequate for the fish to feed maximally, by reference to observations of food intake in larvae allowed to feed over 15 and 30 min (E. Baras, unpublished data).