Effect of fish size, meal size and dietary moisture on gastric evacuation of pelleted diets by yellow perch, Perca flavescens

Abstract

The relationship of stomach volume to fish size, and the influence of meal size, fish size and dietary moisture on gastric evacuation, were evaluated for yellow perch, Perca flavescens. Relative stomach volume was determined as the amount of a standard pelleted diet consumed in a single feeding for three size groups of perch: 13–23 g, 44–54 g and 75–85 g. Gastric evacuation rates for meals of 0.80% and 0.40% body weight were determined for these size groups, and evacuation rates of a 4.7% and 24.1% moisture meal were determined for the 75–85 g fish. The smallest fish had a significantly greater relative stomach volume than either of the other two groups, which did not differ significantly from each other. Gastric evacuation rates were not affected by the size of the fish or by dietary moisture. Gastric evacuation differed significantly with variations in meal size, although differences in evacuation rates were not proportional to changes in meal size.