The common dragonet has a rather flattened head and body and when viewed from above the head is almost triangular in shape, its eyes are close together and on top of the head. In the mature male the first dorsal fin is more that twice the height of the second dorsal fin. Females and immature males are usually pale brown with a series of six darker blotches along the sides and three conspicuous saddle-like markings across the back. Males have numerous blue spots and stripes on their bodies and fins.

The common dragonet is usually found on sandy or muddy, it can be seen on the inshore dive sites where the rocky reefs meet the sandy bottom. It feeds on bottom-living crustaceans, worms and molluscs. The species is widespread all around the coasts of Ireland, including the Cork coast.