The lionfish has a beautifully banded head and body with reddish or golden brown bands stretching across a yellow background. The dorsal and anal fins possess dark rows of spots on a clear background.
Pterois volitans are differentiated from other scorpionfishes by having 13 rather than 12 poisonous dorsal spines and 14 long, feather-like pectoral rays. The anal fin has 3 spines and 6-7 rays.
Pterois volitans can grow to a maximum length of 38 cm.
Some other noteworthy characteristics of Pterois volitans are the bony ridge across the cheek and the flaps that partially cover both the eyes and nose. They also possess a "tentacle" above both eyes.