Heniochus acuminatus

Behavior:

The pennant bannerfish is a social and elegant species often found in pairs or small groups hovering above deep reef slopes and protected lagoons. Unlike its nearly identical cousin, the schooling bannerfish (H. diphreutes), the pennant bannerfish is more likely to be found in pairs and is more closely associated with the reef bottom. They are diurnal foragers, feeding primarily on small benthic invertebrates and occasionally zooplankton. They are generally peaceful and are a common sight for divers in coral-rich environments. The most striking feature of this fish is its extremely elongated fourth dorsal spine, which forms a long, white flowing “pennant” that can be longer than the fish’s actual body. They are frequently confused with the Moorish idol; however, you can distinguish the Pennant bannerfish by its bright yellow tail and pectoral fins, as well as the absence of the orange “saddle” on the snout that characterizes the Moorish idol.

Predators:

Grouper, snapper, and reef sharks.

Did you know?

Juveniles of this species sometimes act as “cleaners,” picking parasites off the skin of larger fish.