Pristicon trimaculatus
A small, rarely-logged cardinalfish spotted in Okinawa's reefs, comfortable in warm 26-29C water year-round. Here's how to spot one.
Small, compact fish around 10 cm, with a big-eyed, blunt-nosed cardinalfish shape typical of the family. Body tone runs reddish-brown to tan, with the namesake three dark spots along the body that stand out against the paler background when a torch or strobe hits it. Usually seen hovering nearly motionless, angled slightly head-down, close to a ledge or crevice rather than out in open water.
Divers find it tucked close to reef structure, hovering in small sheltered gaps rather than swimming out over open sand or coral. Like most cardinalfish it tends to sit still and let divers approach, relying on its low profile and cover rather than fleeing. Given the family's habits, sightings are more likely on slower, close-focus dives where you're checking ledges and crevices rather than cruising past them.
Cardinalfish in this family are mouthbrooders, with the male carrying fertilised eggs in his mouth until they hatch, though this hasn't been specifically documented for this species in the field.
No clear seasonal pattern shows up in the sightings, and the observed temperature range of 25.9 to 29.3C matches Okinawa's reefs for most of the year, 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.
Currently confirmed by divers in Japan, specifically around the Okinawa & Ryukyu Islands, where it has been logged as a rare find on local reefs. Data outside this region is sparse, so treat Okinawa as the known starting point for a deliberate search rather than a wide-ranging guarantee.
Mapping where Threespot Cardinalfish is logged…
The only confirmed diver sightings come from Okinawa & Ryukyu Islands in Japan, where it's logged as a rare find. It hasn't been widely reported elsewhere, so Japan is currently the place to look.
There's no detected season in the sighting data, and the water temperatures where it's been found, 25.9 to 29.3C, hold steady across much of the year in Okinawa. Treat it as a year-round possibility rather than a seasonal event.
Look for a small, reddish-brown cardinalfish around 10 cm long with three dark spots along its body and the big eyes typical of the family. It's usually found hovering close to reef crevices rather than in open water.
They reach around 10 cm, a typical size for small reef-dwelling cardinalfish.
No, they pose no threat to divers. They're small, sheltering fish with no venom or aggressive behaviour towards people.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
Iridescent Cardinalfish
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