Two-spot Goby

The two-spot goby, also called the crab-eyed goby or twin-spot goby, is a small and distinctive goby in the family Gobiidae, the sole member of its genus Signigobius. It is native to sandy lagoons and reef flats of the Indo-Pacific, from the Philippines and Indonesia east to the western Pacific. The species is prized among divers and aquarists for its unusual eyespot markings, which mimic the appearance of a crab, likely serving as a predator deterrent. It typically lives in male-female pairs that share and defend a burrow in sand adjacent to reef structure. Populations appear stable and the species is not considered threatened.

The two-spot goby has a pale, sandy gray-white body with two large black eyespots ringed in blue set high on the rear of the elevated first dorsal fin, resembling a pair of crab eyes when the fin is raised.

• Small, laterally compressed body with a blunt snout
• First dorsal fin tall and often held erect like a fan
• Pelvic fins fused into a disc used for perching on sand
• Sand-sifting feeding behavior, scooping mouthfuls of substrate

Its unmistakable double eyespot pattern separates it from all other gobies, which typically lack such bold ocelli on the dorsal fin.

Two-spot gobies inhabit sheltered sandy lagoons, silty reef flats, and sand patches adjacent to coral reefs throughout the tropical Indo-Pacific, including the Philippines, Indonesia, Papua New Guinea, and northern Australia. They are typically found at shallow to moderate depths of about 3 to 20 meters, in areas with fine sand or silty-sand substrate near reef structure that provides refuge. Pairs dig and maintain a shared burrow in the sand, retreating into it when threatened. The species prefers calm, protected water over exposed high-energy reef edges.

Two-spot gobies are typically found living in monogamous male-female pairs that cooperatively excavate and defend a burrow in the sand near reef structure. They feed by repeatedly scooping mouthfuls of sand, sifting out small invertebrates and organic matter before ejecting the sand through their gills, a behavior that can be observed almost continuously during the day. When alarmed, a pair will raise their dorsal fins to display the crab-like eyespots, a startling display thought to deter would-be predators, before quickly retreating into their burrow. Spawning pairs lay eggs within the burrow, which one parent guards until hatching. Their sand-sifting activity contributes to sediment turnover on reef flats.