This study assessed the suitability and cost e⁄cacy of an equal blend of canola oil (CO) and poultry fat (PF) as a supplemental dietary lipid source for juvenile Atlantic salmon. Quadruplicate groups of Atlantic salmon ( $ 400 g) held in 4000 L outdoor ¢breglass tanks supplied with running (35^40 L min À1 ), aerated (dissolved oxygen, 7.88^10.4 mg L À 1 ), ambient temperature (8.6^10.9 1C) sea water (salinity, 263 5 g L À1 ) were fed twice daily to satiation one of three extruded dry pelleted diets of equivalent protein (488^493 g kg À1 dry matter) and lipid (2672 74 g kg À1 dry matter) content for 84 days. The diets were identical in composition except for the supplemental lipid (234.7 g kg À1 ) source viz., 100% anchovy oil (AO; diet COPF-0),70.2% AO and 29.8% CO and PF (diet COPF-30), and 40.3% AO and 59.7% . Atlantic salmon growth rate, feed intake, feed e⁄ciency, protein and gross energy utilization, percent survival and whole body and ¢llet proximate compositions were not a¡ected by diet treatment. Cost per kilogram weight gain was about 10% less for ¢sh fed diet COPF-60 than for diet COPF-0. Percentages of saturated fatty acids in dietary and ¢llet lipids varied narrowly. Moreover, percentages of 18:1n-9, monounsaturated fatty acids, 18:2n-6, n-6 fatty acids,18:3n-3, and ratios of n-6 to n-3 fatty acids in the £esh lipids were directly related to the dietary level of CO and PF whereas 22:6n-3, the total of 20:5n-3 (eicosapentaenoic acid; EPA) and 22:6n-3 (docosahexaenoic acid; DHA), and n-3 fatty acids revealed the opposite trend. Percentages of 22:6n-3, EPA and DHA, and n-3 fatty acids were signi¢cantly depressed in ¢sh fed diet COPF-60 versus diet COPF-0.We conclude that a 1:1 blend of CO and PF is an excellent cost-e¡ective dietary source of supplemental lipid for Atlantic salmon in sea water.