Temperature preference and acclimation in Poecilia sphenops (Pisces, Poeciliidae)

Abstract

The preferred temperature (PT) of Poecilia sphenops (Pisces, Poeciliidae) (n = 240

1.13 +/- 0.06 g wet weight

3.26 +/- 0.88 cm standard length) from Presa Piedra Azul, Oaxaca, Mexico, was measured at acclimation temperature of 20 degreesC, 23 degreesC, 26 degreesC, 29 degreesC, 32 degreesC and 35 degreesC. The thermal preference of males was 25.5 degreesC in summer and 29.6 degreesC in winter

whereas females preferred 29 degreesC in both seasons. Fish held at 20 degreesC and 23 degreesC preferred temperatures 36% higher than their acclimation temperature (AT), and those held at 35 degreesC and 32 degreesC preferred 30% and 20% lower temperatures than their AT. In intermediate temperatures, no significant differences between PT and AT were found. The interval of thermal selection based on the higher (HAT) and lower (LAT) avoidance temperatures was of 10-14 degreesC and not different between sexes in both seasons. Knowledge of the thermal biology of P. sphenops based on the preferred and avoidance temperatures was very important in order to understand the capacity of the species to adapt to the thermal changes occurring in its habitat. Based on the results, we can recommend the use of P. sphenops in aquaculture owing to its thermal plasticity.