Temperature preference of newly feeding fry of two species of Salmo, three species of Salvelinus, and seven hybrids were determined in a horizontal gradient. Fry of species in the genus Salmo and intergeneric hybrids with female parent in Salmo selected significantly higher temperatures (13.0–15.0 °C, P < 0.05) than did fry of species and hybrids of the genus Salvelinus (9.0–11.5 °C). No significant differences were obtained among species and hybrids within either of the two groups described above. Preferred temperatures of fingerlings (after 3 mo of feeding) of two species and two hybrids within Salvelinus were determined in a vertical temperature gradient. Brook trout preferred 17.5 °C, and lake trout 10.8 °C. The two hybrids (brook trout × lake trout and lake trout × brook trout) preferred intermediate temperatures (14.7 and 14.4 °C). Rainbow trout fingerlings selected 14.7 °C. Key words: temperature, preference, Salmo, Salvelinus, hybrids, gradients