Temperature preferendum of postlarval black tiger shrimp (Penaeus monodon)

The environmental temperatures preferred or selected by postlarval black tiger shrimp Penaeus monodon (body weight 84 +/- 25 mg and body length 2.66 +/- 0.21 cm, mean +/- s.d.) acclimatized to 16, 20, 24, 28, 32 or 36 degrees C, were determined in a horizontal gradient (17-37 degrees C). The results indicated that the crustaceans were competent in detecting thermal discontinuities and in showing preference. The mean temperature selected by the postlarvae rose from 20.0 degrees C to 25.6 degrees C and the mode from 15 degrees C to 27 degrees C when the acclimation temperature was increased from 16 degrees C to 36 degrees C. The preferred temperature of the shrimp was not significantly different among the groups acclimatized at 24 degrees C, 28 degrees C and 32 degrees C. The final preferendum of the shrimp was estimated to be 23.2 degrees C, which is considerably lower than the optimal growth temperature for the species.