The division of food resources among 13 demersal fishes was examined over a 16-month period in an area of Passamaquoddy Bay, New Brunswick. Though over 100 prey species were found in the stomachs of the predators, each predator took only three or four principal prey, and these prey made up 70–99% of the mass of the food for each predator species. Which species that a predator took as principal prey depended on prey body size, whether the prey were nekton, epi-fauna, or in-fauna; and whether or not they had a hard test or shell. Within predator species there was significant heterogeneity in diet related to size of predator individual.The seasonal predators did not feed as a group on their own set of prey species. Most principal prey species of the seasonal predators were taken simultaneously by one or two of the regulars.Data were compared with published results from two other northern marine areas. Within Irish Sea, Sea of Okhotsk, and also Passamaquoddy winter and summer communities, only 10–24% of the possible recurrences of principal prey among predators actually occurred, i.e. there was relatively little overlap among diets. Such specialization would have adaptive significance in a food-limited production system.