The subfamily Pteroinae, a widely distributed Indo-Pacific group, contains five genera and 27 species, including the well-known, invasive Red Lionfish Pterois volitans and Devil Firefish P. miles. Other species are imported in the marine ornamental trade; however, basic biological information for most is scarce or absent, which can make the determination of invasion risk difficult. Thermal tolerance is an important physiological characteristic which can limit the distribution of non-native fishes. Here we assess the thermal tolerances of two commonly traded lionfishes in the ornamental pathway, Shortfin Turkeyfish Dendrochirus brachypterus and Zebra Turkeyfish Dendrochirus zebra, using chronic lethal methodology. Average chronic lethal minimum temperature was 11.8°C for Shortfin Turkeyfish and 14.7°C for Zebra Turkeyfish, compared to 10.0°C for Red Lionfish. Our results suggest a narrower potential distribution in the Atlantic for both species if they were to establish outside captivity. These findings are useful for future risk assessment which can inform regulatory actions, if necessary, and ultimately mitigate deleterious introductions.