The head is bluntly rounded with high set eyes and a small mouth.

The eyes are deep blue or green in colour with a yellow or orange iris.

The upper parts of the body range from black to dark brown to dark green in colour and is covered in pale yellow or white blotches, although juveniles tend to be paler than adults.

Some individuals have a yellow line dividing the darker and paler parts of the body.

When startled, it will typically inflate and hang in the water before suddenly deflating and rapidly swimming away.