Critical thermal maxima and minima for curimbatá, Prochilodus scrofa Steindachner, of two different sizes

Critical thermal maxima (CTMax) and minima (CTMin) were determined for Prochilodus scrofa Steindachner of two sizes (19.5 ±7.2 g and 249 ± 42.4 g). acclimated at 15. 20, 25, 30 and 35 ± 1°C. The CTMax and the CTMin for the smaller fish were 33.9. 36.7. 38.7, 40.3. 42.0°C and 5.0, 7.2. 9.2. 10.3. 13.4^oC and for the larger (Ish 33.3, 35.7, 38.2. 40.6. 42.6°C and 6.5, 8.2. 10.8. 12.4, 14.6°C. respectively, at each acclimation temperature. The CTMin from smaller fish were significantly lower than those from larger ones but the CTMax did not show any such difference. These results indicate that P. scrofa is suitable for culture in south-eastern and even in southern Brazil where winter temperatures may drop to very low levels, mainly at night. The zone of thermal tolerance calculated by CTMax and CTMin was equivalent to 1046°C² and 964.2°C², respectively, for smaller and larger fish, showing a high degree of eurythermicity.