Thermal ecology of Poeciliopsis gracilis in the Pánuco basin

Specimens of P. gracilis were collected in the Santiago River under the Jihuico bridge, which were acclimatized and maintained at 25 °C to carry out the necessary evaluations in the laboratory.The critical temperatures (Tcmin: 9.2 °C, Tcmax: 40.8°C) and the preferred temperature range (Tp: 27.9 -29.2 °C) were determined.Likewise, performance tests were carried out under different thermal treatments to generate a locomotor performance curve.With the best model for the performance curve, it was determined that the temperature range in which organisms can swim from their maximum speed to 80% of this value is B 80 : 21.4 to 35 °C.Additionally, data from the National Collection of Mexican Fresh water Fishes (ENCB-IPN-P) were consulted to obtain records of the species in the Pánuco basin and the availability, use and preference of habitat was calculated, the thermal limits in field for the species 17.2 -32.5 °C, with a thermal preference range of 27.5-30 °C.The thermal preference ranges and the range of optimal temperatures estimated with field data coincide with those obtained in the laboratory.