Blue Devil Damselfish Identification Guide

Key identification features

• Entire body a deep, saturated electric blue with no yellow patches
• Deep, oval, laterally compressed body shape typical of damselfish
• Males often develop a black patch or spot at the base of the dorsal fin and sometimes on the tail
• Small size, usually 2-3 inches (5-8 cm)
• Slightly forked tail and pointed snout

Common look-alikes

• Yellowtail blue damselfish shares the same blue body but has a solid bright yellow tail, which the blue devil lacks.
• Springer's damselfish has a grey-white body with a bold black eye mask rather than being blue throughout.
• Neon damselfish is a similar blue but slimmer-bodied with a small yellow patch near the tail base instead of a fully blue tail.

Where you'll see one

Blue devil damselfish inhabit shallow lagoon and outer reef flats across the Indo-Pacific, from East Africa to the western Pacific islands. They are typically seen singly or in small groups hovering above branching coral or rubble, retreating quickly into crevices when approached, and are one of the most common small blue reef fish seen while snorkeling in shallow water.