A method for estimating the daily food consumption of 0-group plaice in the sea is described. Eight series of samples were taken, four in the summer and four in the autumn. Each series was comprised of eight pairs of samples taken at 3-h intervals. One of each pair was preserved immediately, the other was held in deck tanks until the next pair of samples was taken. The difference between the mean stomach contents of the sample held in the deck tank and that of the sample caught three hours later, and preserved at the time of capture, is a measure of the food consumed in the 3-h interval. The fish show a tendency to commence feeding on the ebb tide after day break. They cease to feed shortly after sunset, except when there is a full moon. Then they may continue to feed through the night. In July the fish consumed 8 to 11 % their body weight per day and in September–October 1 to 3 %. This decrease in feeding level was not related to sea temperature.