Foa fo
A rare 3cm reef dweller logged near Dili, Timor-Leste and Luzon, Philippines in warm 24-29C water.
A tiny fish, topping out around 3 cm, with a slender, faintly translucent body typical of small cardinalfish. Look for the large eyes and blunt, rounded head that give it away as an apogonid, and its habit of hanging almost motionless close to structure rather than swimming out in the open. At this size and with no bold stripes or spots to key on, careful close-focus viewing is needed to separate it from similar small cardinalfish sharing the same reef.
Divers report this one as a rare to uncommon find, tucked in close to reef structure rather than out cruising open water. Like most small cardinalfish it likely stays sheltered by day and becomes more active around dusk, holding station near crevices or rubble where a slow, patient look is rewarded more than a fast swim-by.
Cardinalfish as a family are known for male mouthbrooding, carrying fertilised eggs in their mouth until they hatch, a trait worth watching for if you spot a pair close together on the reef.
There isn't enough logged data to show a clear season, and its comfortable range of roughly 24 to 29C spans typical year-round tropical reef temperatures in both Timor-Leste and the Philippines, so it's best treated as a possible sighting any month.
Reef neighbours a diver could mistake it for. Use the identification notes above to tell them apart.
Logged sightings so far come from just two spots: a site off Dili in Timor-Leste and one in Luzon, Philippines, making it a real rarity on both muck and reef dive itineraries in the region. If you're chasing this one specifically, plan around these two known locations rather than expecting it on a generic Coral Triangle checklist.
Mapping where Weedy Cardinalfish is logged…
Confirmed sightings are limited to a site near Dili in Timor-Leste and a site in Luzon, Philippines. It's considered rare, so treat any sighting there as a bonus rather than a guarantee.
There's no detected seasonal pattern in the sightings, and it lives in water between roughly 24 and 29C, which fits year-round tropical conditions in both Timor-Leste and the Philippines. Any time of year is as good as any other.
It's a small, slender fish around 3 cm long with large eyes and a plain, unpatterned body typical of many small apogonids. Without bold stripes or spots, close and careful observation near reef structure is needed to tell it apart from similar species.
They're small, reaching around 3 cm in length, making them one of the tinier cardinalfish a diver might spot on the reef.
Like other cardinalfish, it likely uses male mouthbrooding, where the male carries fertilised eggs in his mouth until the young hatch, a distinctive reproductive strategy within the family.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
Iridescent Cardinalfish
1,784 sites
