Nemateleotris decora
Spot the Elegant Firefish in Indonesia's Sumatra & Kalimantan reefs. Purple-tipped fins and a hovering posture make it one of the reef's most distinctive gobies.
A slender, hovering goby with a white-to-pale-lavender body and a dramatically elongated first dorsal spine that it raises and lowers like a flag. The key marks are the vivid purple-blue and orange banding on both dorsal fins and the dark-edged caudal fin, which together give a flame-like colour pattern unlike anything else on the reef. It typically hovers just centimetres above the substrate, angled slightly head-up, retreating tail-first into a hole when approached.
Elegant Firefish hover just above sandy rubble or coral slope edges, usually alone or in loose pairs, facing into the current to pick off passing zooplankton. They are shy; a diver moving too quickly or too close will send them reversing into their burrow instantly. Slow, patient approaches from a distance are the best way to observe them for any length of time.
Like other dartfish, elegant firefish maintain a burrow into which they disappear at the first sign of danger, and pairs have been observed sharing the same refuge, suggesting monogamous pairing behaviour on the reef.
No strong seasonal peak has emerged from logged sightings, so it can be treated as a year-round resident. Observed water temperatures run 27 to 30 °C, consistent with warm tropical reef conditions throughout the year.
Reef neighbours a diver could mistake it for. Use the identification notes above to tell them apart.
Most diver observations come from Indonesia, with the overwhelming majority logged across sites in Sumatra and Kalimantan. There is also a sighting from Kadavu, Fiji, suggesting the species has a broader Indo-Pacific range than the current log reflects.
Mapping where Elegant Firefish is logged…
The vast majority of diver sightings come from Indonesia, particularly around Sumatra and Kalimantan. There is also a confirmed sighting from Kadavu, Fiji. If you are planning a trip specifically to find one, Indonesian reefs in the Coral Triangle region offer the best current odds.
There is no clear seasonal peak in the sighting data, so year-round diving applies. Logged water temperatures sit between 27 and 30 °C, meaning any visit to warm Indonesian reef sites has a reasonable chance of an encounter.
Look for a slender, pale-bodied goby hovering just above the reef with its elongated first dorsal spine raised. The vivid purple-blue and orange banding on the dorsal fins is the clincher. It hovers head-up and retreats tail-first into a burrow when spooked.
At sites where it has been recorded, it is typically classed as uncommon, with a minority of sites rating it rare. Patience and slow movement near rubble slopes give you the best chance before it retreats into its burrow.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
Slender Goby
803 sites
