Lionfish tolerate a wide range locations, temperature, depth and salinity and are found throughout tropical and subtropical areas including:
Lionfish exhibit high site fidelity and studies have shown 74% do not venture further than 10 meters/ 33 ft from capture location (Jud & Layman 2012).
Temperature appears to be a limiting factor on lionfish distribution. Lionfish have been observed in water as cold as 13°C/56°F and as warm as 30°C/86°F. Based on the tolerance of lionfish to cooler temperature scientists have estimated the potential future range based on the lethal thermal minimum of 10°C / 50°F. This predicted range is indicated in the red hatched shaded area in the map below. However, studies have shown that lionfish stop feeding at temperatures of 16°C/61°F and cooler, so in order to survive in the cooler temperatures they would need to adapt.
In their native range lionfish have been found in water depths to 175 meters/ 575 feet. In Belize lionfish have been caught by fishermen bottom fishing off the drop off in water depth greater than 152 meters/500.
Studies have shown them to tolerate low salinity waters of 10 ppt, normal sea water is about 35 ppt.
Thermoclines of oceans indicates a sharp decrease in temperature between 300-600 ft. Given temperature limits distribution they would not survive much deeper than 500 ft.