Experimental data on the relationship between growth and feeding of some of the common gadoids in captivity are presented and discussed. For fish of a particular body weight, there is a linear relationship between daily growth in weight and daily energy intake up to the limit of the appetite of the fish. Regression lines were fitted to data of growth per day on food per day for fish of different body weights. The effect of body weight on the intercepts and slopes of these regressions was investigated. The intercept on the food per day axis, which is equivalent to the daily maintenance ration, was related to body weight raised to the power 0·7–0·8. The effect of temperature on the metabolic rate was also considered. Published data on the effect of temperature on oxygen consumption were used to derive a general formula allowing for the effect of temperature on maintenance. This formula is: maintenance = 0·0080 (exp 0·081T)W0·8 kcals/day, where T = temperature (°C) and W = body weight (g). The slopes of the regression lines provide estimates of net conversion efficiency and these also were found to be related to body weight. This coefficient appeared to decline relatively rapidly with body weight in the range 5 to 100 g, but no change with body weight could be detected over the weight range 100 to 900 g. Over the range 5 to 900 g, net conversion efficiency can be empirically related to body weight by the equation: net conversion efficiency = 0·79 W−0·15 g/kcal. The experimental results were summarised in the form of empirical relationships between food intake, F, (in kcal/day) and growth, G, (in g/day). These are: G = [0·79FW−0·15 − 0·0063W0·65 exp (0·081T)] g/day at T°C and F = [0·0080W0·8 exp (0081T) + 1·27GW0·15] kcals/day at T°C.