Fish were sampled in two successive years in a canal in north-west England with heavy boat traffic (10 000 mh−1yr−1). An energy budget was used to calculate the food consumption of the two most dominant species, roach Rutilus rutilus and gudgeon Gobio gobio. For two subdominant (perch, Perca fluviatilisand ruffe, Gymnocephalus cernuus) and four rare species living there, parameters of the energy budget and prey consumption were estimated using ecological indices calculated for both dominants. The food conversion efficiency was low compared with values for the same species in other habitats, probably because of detritus and scarcity of macrobenthos in the diet. This may have been a result of the heavy boat traffic.