Thermoregulatory behavior and critical thermal limits of the angelfish Pterophyllum scalare (Lichtenstein) (Pisces : Cichlidae)

(1) Final temperature preferendum of juvenile (0.9-1.9 g) and adult (5.2-12.5 g) angelfish Pterophyllum scalare were determined with acute and gravitation methods. The final preferenda were similar, independent of the method and development stage (29.0-31.1degreesC). (2) The critical thermal maxima (CTMax) for juveniles were 36.9degreesC, 37.6degreesC, 40.6degreesC, 40.8degreesC and for adults 38.4degreesC, 38.6degreesC. 41.0degreesC. 42.1degreesC. Adult angelfish CTMax was slightly higher than in juveniles (1degreesC; P<0.05); the endpoint of CTMax was the onset of spasms. (3) The acclimation response ratio for both stages had an interval of 0.33-0.44; these values are in agreement with results for subtropical and tropical fishes. (4) Therefore it is recommended that angelfish cultivation should be consistent with temperatures that do not change abruptly throughout the year and temperature maximum does not exceed 30degreesC.