Bar Jack

Bar Jack, Commensal Feeding

In this photo, the Bar Jack and a Trumpetfish are following a Black Margate to feed on prey stirred up from the seafloor. This opportunistic behavior is known as commensal feeding.

The Bar Jack has a dark bar running along its back, with a bright, iridescent blue stripe directly beneath it. Its streamlined body is typically a silvery color, transitioning from a bluish-gray on its upper half to a pure white on its underside. When it is actively feeding, the silvery-blue hue on its body can darken considerably.

This Jack is mostly found solitary or in small groups in clear, shallow waters. It is known for its opportunistic feeding behavior, sometimes following other fish to snatch food stirred up from the seafloor. Bar Jacks are also common around bait balls, where they hunt small fish in fast, coordinated bursts. Juveniles often seek shelter near pilings and dock areas, or with floating Sargassum seaweed.