dorsal fin

It has silvery blue skin and a red dorsal fin that runs the length of its body.

A dorsal fin cut the surface close by, there was a little flurry, and the pirate disappeared.

The back, dorsal fin and tail are generally well covered with dark brownish black spots.

Dorsal fin double, the first half having ten spines and the latter twenty-one or twenty-two soft rays.

The unpaired dorsal fin develops as a continuous thickening, which then grows up into a projecting fold of columnar cells.

The dorsal fin runs along the whole length of the back, and each pelvic has one spine and two soft rays.