Organic and caloric levels of fish feces relative to its consumption by coprophagous reef fishes

Levels of protein, lipid, carbohydrate, ash, and calcium in the rectal contents of a species representative of each of four trophic groups of coral reef fishes were determined. These levels and the estimated caloric levels were related to the degree to which the feces of each species were eaten by species of coprophagous fishes and to the potential nutritional value of their non-fecal foods. The potential nutritional value of feces (based on estimated caloric content), protein and lipid levels were positively correlated with the percentage of feces eaten by coprophagous fishes. Levels of calcium and ash were negatively correlated with the percentage eaten. Fecal carbohydrate level was not correlated with the degree of ingestion. Food values of these feces were at least equal to those of non-fecal foods (i.e. zooplankton, coral tissue, algae, etc.) of the coprophages. Feces produced by the coprophagous species had even lower potential food value.