The gut contents of rainbow trout (Salmo gairdneri), kokanee (Oncorhynchus nerka), and two salamanders (Ambystoma gracile and Taricha granulosa) from Marion Lake were compared. The species found in these four predators were very similar but each predator concentrated on different prey. The kokanee concentrated on species present at the surface or in the water column, and the trout on larger benthos. The salamanders also fed on benthos but usually chose smaller size classes. In comparing the effect of the four predators, the average volume of food present by weight in the gut was multiplied by a proportional converter for the rate of passage through the gut, the mean meal size, and by the number of individuals in the population. The results suggested that Salmo gairdneri ate over half by weight (56%) of all the food taken by the four predators combined; kokanee and Ambystoma gracile were less important and consumed 25% and 19% respectively; and Taricha granulosa because of its low number and slow growth was unimportant (1%).