The effect of temperature on growth and feed utilization was studied over 56 days in Atlantic cod of different haemoglobin subtypes [designated Hb-I(1/1), Hb-I(1/2), and Hb-I(2/2)]. The fish, held in triplicate tanks, were reared at 6 and 14 °C (mean initial body weight, 218 and 212 g, respectively). These temperatures are close to the preferred temperatures of Hb-I(2/2) (8.2 °C) and Hb-I(1/1) (15.4 °C). Temperature had a significant effect on SGR, with cod of all haemoglobin variants growing best at 14 °C (P < 0.05). There was no significant effect of Hb-I⁎ subtype on SGR. Since cod of type Hb-I(2/2) had a higher SGR at 14 °C than at 6 °C this suggests that the temperature preferendum may not provide a good indicator of optimum growth temperature. Significant differences between the Hb-I⁎ variants were detected in several nutritional indicators. At 14 °C, the feed efficiency was poorer in the Hb-I(1/2) cod (0.99 ± 0.08) than in the Hb-I(1/1) and Hb-I(2/2) fish (1.35 ± 0.05 and 1.52 ± 0.07, respectively). Energy retention was significantly lower in the Hb-I(1/2) fish (19.5 ± 3.7%) than in the Hb-I(2/2) fish (43.8 ± 1.8%) at 14 °C. Regardless of the Hb-I⁎ subtype, retention of macronutrients and conversion efficiencies were better in fish reared at 6 than 14 °C.