Sex Differences in Thermal Tolerance of Nine Ornamental Fish Species from the Poecilidae, Cichlidae and Cyprinidae Family

Thermal tolerance and intersexual differences of nine ornamental fish species (Chindango demosoni, Aulonocara stuartgranti, Mylandia lombardoi; Cichlidae; Carassius auratus, Pethia conchonius, Branchydanio rerio; Cyprinidae; Xiphophorus helleri, X. maculatus, Poecilia reticulate; Poecilidae) were determined in this study. CT-min of the species ranged between 9.63 and 11.37 in poecilids, 11.29 and 12.53 in cichlids, 4.67 and 8.46°C in cyprinids, while CT-max ranged between 39.12 and 40.53 in poecilids, 37.82 and 39.37 in cichlids, 36.12 and 40.30°C in cyprinids. While intersexual differences in the CT-min/CT-max values were not evident in cichlids and cyprinids, these values significantly differed across poecilids. The females of poecilids were approximately 0.5 to 1°C more resistant to both low and high temperatures than their males. Among the species included in our study, due to their resistance to low temperature, especially C. auratus and a lesser extent B. rerio and P. conchonius were considered the most suitable ones for outdoor aquaculture in subtropical regions. However, if they are cultured outside of their natural distribution, it should be noted that upon escapement from aquaculture facilities to nature, they may interfere with the ecosystem and compete with native species there due to their wide range of thermal tolerance.