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Dascyllus trimaculatus

A dark damselfish up to 14 cm long, found from the Red Sea to the central Pacific. 1 2 As a juvenile it is black with a white spot on the forehead and one on each flank, and often lives among sea anemones or sea urchins; as an adult the spots shrink or disappear. 2 4 It is among the marine fish most imported for aquariums. 10

PomacentridaeIUCN: Least concern
Dascyllus trimaculatus

At a glance

Data from the scientific sources listed at the bottom.

Depth in the wild

0–55 m

0 m20 m40 m60 m80 m100 m

Size

up to 14 cm

03691215

maximum total length (males or unsexed specimens)

Conservation

NEDDLCNTVUENCREWEX

IUCN Red List: least concern (2021). Red List data taken from FishBase and GBIF. 2 11 It does not appear in the CITES lists checked on Species+. 12 Anemone bleaching can reduce its recruitment: in bleached anemones newly settled juveniles were three times fewer and, in an experiment, more of them died from predation. 8

Where it lives

Red SeaWestern Indian OceanEastern Indian OceanCentral Indo-PacificWestern PacificCentral PacificEastern PacificWestern AtlanticEastern AtlanticMediterranean

From the Red Sea and East Africa to the Line Islands and the Pitcairn Islands; north to southern Japan, south to Sydney. It does not live in Hawaii or the Marquesas. 2 Closely related species live in Hawaii, the Marquesas and the Line Islands and form a group of four species with it. 5 The Indian Ocean and Pacific populations are distinct genetic lineages, with slight differences in colour, that interbreed at Christmas Island and the Cocos Islands. 6

How to recognise it

Tap a number on the photo: the key explains what to look for.

123
  1. 1Forehead spot present in the juvenile, missing in the adult 2 4
  2. 2Flank spot high up; it shrinks and disappears with age 2 4
  3. 3Black body in the juvenile, with scales often bluish in the centre 2 4

Life in the wild

Where it is found

Coral and rocky reefs and mangrove lagoons, usually near branching corals. Adults frequent coral heads and large rocks; juveniles shelter among the spines of Diadema sea urchins, in large anemones or in branching corals. 2 4 7

What it eats

Algae, copepods and other small planktonic crustaceans have been found in the stomachs. 2

Behaviour

It lives in small to large groups and is active by day. 2 Immature individuals stay on or near host anemones. 7

Reproduction

It forms pairs to breed: the eggs stick to the bottom and the male guards and fans them. Courtship includes signal jumps by the male. 3 It was once thought to change sex from female to male; more recent studies indicate that the sexes are separate and that the change is not functional. 3 4

In the aquarium

From the experience of the BallingMania community.

Community rating
Swimming level
lowmediumhigh
Coral compatibility
lowmediumhigh
Aggression
lowmediumhigh
Care difficulty
lowmediumhigh
Original sheet

It is a community fish, and it is extremely aggressive towards species of the same family; very territorial, it is not recommended for beginner aquarists as it readily attacks both large fish and the aquarist's hand. It adapts to any situation, and if introduced as the first fish it is hard to add others later on; to reduce its aggression it should never be kept with other identical specimens or ones with a similar livery. By day it lives on the reef front or above the reef, while at night it hides under the rocks. It is an omnivorous fish and gets used to dry food easily; once placed in the aquarium it needs a couple of days to settle; if you decide to add it to the tank, keep it as the last fish. Once it has found its territory it will clear out all the fish that swim around it. It can be recognised by its blackish-brown colour and the three whitish spots on the post-caudal area.

Photo by: Lubomír Klátil

What studies say about keeping it

A figure reported by FishBase, not advice for a home aquarium: a pair in captivity spawned three times a month, for a total of 17 spawnings in 7 months. 3 In the United States it was the third most imported fish species in 2008 and 2009 and the fourth in 2011, with 3.7-5% of specimens. 10

Did you know?

The name trimaculatus means 'three-spotted' and refers to the three white spots of the juveniles. 4
In a group of 181 juveniles that settled together on a small reef in French Polynesia, 11 groups of siblings were found: it was the first evidence that siblings can stay together through the whole larval phase, which lasts almost a month. 9
It has an odd number of chromosomes, 47: one parent passes on 24 and the other 23. 5

Sources

  1. WoRMS Editorial Board (2026). Dascyllus trimaculatus (Rüppell, 1829). World Register of Marine Species.
  2. Froese R., Pauly D. (eds.) (2026). Dascyllus trimaculatus, Threespot dascyllus. FishBase.
  3. Froese R., Pauly D. (eds.) (2026). Reproduction of Dascyllus trimaculatus. FishBase.
  4. Bray D.J. (2025). Threespot Humbug, Dascyllus trimaculatus (Rüppell 1829). Fishes of Australia.
  5. Roberts M.B., Schultz D.T., Gatins R., Escalona M., Bernardi G. (2023). Chromosome-level genome of the three-spot damselfish, Dascyllus trimaculatus. G3: Genes, Genomes, Genetics.
  6. Salas E., Hobbs J.A., Bernal M.A. et al. (2020). Distinct patterns of hybridization across a suture zone in a coral reef fish (Dascyllus trimaculatus). Ecology and Evolution.
  7. Hayashi K., Kuwamura T., Tachihara K., Reimer J.D. (2022). Large host anemones can be shelters of a diverse assemblage of fish species, not just anemonefish. Journal of Fish Biology.
  8. Besson M. et al. (2022). Anemone bleaching impacts the larval recruitment success of an anemone-associated fish. Coral Reefs.
  9. Bernardi G., Beldade R., Holbrook S.J., Schmitt R.J. (2012). Full-sibs in cohorts of newly settled coral reef fishes. PLoS ONE.
  10. Rhyne A.L., Tlusty M.F., Szczebak J.T., Holmberg R.J. (2017). Expanding our understanding of the trade in marine aquarium animals. PeerJ.
  11. GBIF Secretariat (2026). Dascyllus trimaculatus, IUCN Red List category. GBIF.
  12. UNEP-WCMC (2026). Search for Dascyllus trimaculatus in the CITES lists. Species+.

Sources checked on 5 November 2026. Community texts and ratings are kept separate from the scientific data.

Download the original sheet (Italian)All species