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,…

While biologists have been aware of the existence of native Mexican trouts for over a century, they have received little study. The few early studies that did muchmore than mention their existence began in the 1930s and continued into the…