Dascyllus marginatus
A small grey damselfish found hovering over Red Sea reefs in South Sinai, Aqaba and Eilat, comfortable in 24.5-29.1C year-round.
A pocket-sized damselfish at around 4 cm, with a stocky, oval body and a grey to brownish base colour that darkens toward the tail. Look for the pale, almost white margins on the dorsal, anal and tail fins, which is where the common name comes from and the easiest feature to pick out against the darker body. It shoals in loose clusters just above coral heads rather than swimming out in open water.
Divers typically find it hovering in small, loose groups just above a single coral head or rubble patch, ducking back into cover the moment a shadow passes overhead. It's a shallow reef-dweller that sticks close to a home patch rather than roaming, so once you spot one colony you'll often find the same fish there on a repeat dive. Most sightings are logged as uncommon rather than abundant, so it rewards divers who slow down and check individual coral heads instead of scanning open water.
Like other dascyllus damselfish, it likely guards a small patch of reef and will dart at intruders many times its own size, a disproportionate bit of attitude for a 4 cm fish.
No clear seasonal pattern shows up in the sighting data, and its comfort range of 24.5 to 29.1C covers the Red Sea's water temperature nearly all year, so it's a fair bet on any dive trip to the region regardless of month.
Reef neighbours a diver could mistake it for. Use the identification notes above to tell them apart.
Most reliably logged across the northern Red Sea, with strong numbers in South Sinai, Egypt, and a steady presence in Aqaba, Jordan and Eilat, Israel. Marsa Alam & the Deep South and the wider Red Sea Riviera in Egypt also turn up sightings, making this essentially a Red Sea speciality rather than a species you'll find on Indo-Pacific reef trips.
Mapping where Marginate Dascyllus is logged…
It's a Red Sea speciality, most often logged in South Sinai, Egypt, as well as Aqaba, Jordan and Eilat, Israel. Marsa Alam and the Red Sea Riviera in Egypt also have populations, but you won't find it on typical Indo-Pacific reef trips.
There's no strong seasonal signal in the sightings, and it tolerates the Red Sea's typical 24.5 to 29.1C range comfortably, so it's present on reefs year-round rather than tied to a specific season.
Look for a small, oval-bodied damselfish around 4 cm long, greyish-brown overall, with pale white edges along the dorsal, anal and tail fins. It typically hovers in small loose groups just above a coral head rather than swimming in open water.
They stay small, topping out at around 4 cm, which is typical for damselfish in the Dascyllus genus.
No, they pose no threat to divers. At most they'll dart aggressively at anything that gets too close to their patch of reef, but this is purely a territorial display with no real risk.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
Yellowtail Clownfish
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