Gunnellichthys curiosus
A slender 8cm goby logged in Hawaii and Fiji reefs, 24-29C water, seen year-round but always uncommon.
A slim, elongated body only about 8cm long, more eel-like than typical reef gobies, with a pale to sandy-grey base colour that blends into rubble and sand patches. It hovers with a gently undulating swimming motion rather than perching flat on the substrate like most gobies. Look for the tapered, almost worm-like profile and the way it holds a near-vertical posture just off the bottom near a burrow.
Divers find it hovering just above sand or rubble patches near its burrow, holding a slightly tilted, elongated posture rather than resting flat like a typical goby. It tends to stay close to cover and will dart back into its hole if you approach too fast, so a slow, low approach gives the best look. Sightings so far have been logged as uncommon even at the sites where it turns up, so patience over a sandy patch pays off more than active searching.
Its genus name, Gunnellichthys, refers to a slender, eel-like body shape shared by several wormfish species that use burrows in sand or rubble as a bolt-hole rather than living openly on the reef like most gobies.
No clear seasonal pattern shows up in the data, and the 24.1 to 28.8C range it's been observed in covers most of the year on tropical reefs, so it's best treated as a year-round possibility rather than a seasonal target.
Reef neighbours a diver could mistake it for. Use the identification notes above to tell them apart.
Logged sightings come from Hawaii in the United States and the Lomaiviti region of Fiji, so both are worth targeting if this species is on your list. Numbers are thin everywhere it has been recorded, so treat any sighting as a bonus rather than a guarantee on a given dive.
Mapping where Curious Wormfish is logged…
Confirmed sightings are limited to Hawaii in the United States and the Lomaiviti region of Fiji. It's an uncommon find even at those sites, so it's not a fish to plan a whole trip around, but worth watching for over sand and rubble patches there.
There's no detected season in the sighting data, and its water-temperature range of roughly 24 to 29C spans most of the year on the reefs where it's found, so year-round is the honest answer.
Look for a slender, elongated body around 8cm long with a pale, sandy colouring, hovering at an angle just above the substrate near a burrow entrance. Its undulating swimming style and worm-like profile set it apart from stockier reef gobies.
They stay small, reaching roughly 8cm in length, which is typical for wormfish in the Gunnellichthys genus.
It belongs to a small group of gobies with an unusually slender, eel-like body built for retreating headfirst into burrows in sand or rubble, a very different lifestyle from the perch-and-dart habit of most reef gobies.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
Slender Goby
803 sites
