J. smithi has a slightly compressed, oblong body with two
dorsal fins, the first having a deeply notched membrane with the third and fourth spines being the longest. The second dorsal fin is much taller than the first. The
anal fin starts slightly behind the front edge of second dorsal fin. The
caudal fin is rounded, but may be truncated. The mouth is slightly oblique and terminal, and stretches back to line up with the rear margin of the large eye. The
preoperculum edge is serrated, with three to seven flat, small serrations at the angle of the lower rear border. The scales are large and finely
ctenoid. The lateral line has 24-26 scales and the one or two scales at the base of the caudal fin lack pores. It is light tan in colour, becoming paler towards the whitish belly, with five or six faint, dark bars which fade completely in larger specimens. The front portion of the front dorsal fin is black with a series of black dots forming a line on the lower third of the rear dorsal fin. The outer margins of the second dorsal and the rear margins of the caudal fins are black. The
pectoral fins and
pelvic fins are transparent, darkening from white to light grey as the animal grows. Normally between 4–10 cm in length, they have a maximum length of 15 cm. ==Distribution==