Firefish and dartfish

Purple firefish

Nemateleotris decora

Also sold as Elegant firefish, Decorated dartfish

Good first fish

Purple firefish (Nemateleotris decora), photographed in the sea or an aquarium — Photo: TANAKA Juuyoh, CC BY 2.0, via Wikimedia Commons

Care level: Beginner
Adult size: 8.3 cm in aquariums
Minimum tank: 76 litres
Temperament: Peaceful
With corals: Reef safe
Captive-bred: Wild-caught (captive-bred rare)
IUCN status: Least Concern

Show volumes inLitresUK gallonsUS gallons

How do you care for the purple firefish?

Peaceful; territorial with own kind.

Feeding

Carnivore.

Vitamin-enriched foods keep colour.

Tank and special needs

Plan for at least 76 litres of water (the care sheet says 20 US gallons).

Tight lid; rubble.

Corals and invertebrates

None.

Which tankmates suit the purple firefish?

As firefish.

Suggested order in a mixed tank: add early, with the first peaceful fish.

More than one purple firefish

Only as a mated pair, or two juveniles added together. A third purple firefish is usually driven out.

Other fish

Checked against the other 59 fish in this guide, assuming a tank big enough for both. Individual fish differ, so treat this as a starting point.

Take care (5)

Maroon clownfishMaroon clownfish is aggressive and may bully the purple firefish, especially if the bully is added first.
Midas blennyMidas blennies are known to nip firefish and small gobies.
Humbug damselHumbug damsel is aggressive and may bully the purple firefish, especially if the bully is added first.
Six line wrasseSix line wrasses often bully peaceful wrasses, firefish and dartfish, especially in small tanks.
Powder blue tangPowder blue tang is aggressive and may bully the purple firefish, especially if the bully is added first.

Usually fine together (54)

Invertebrates

Only the invertebrates with a known risk are listed.

Take care (2)

Tiger tail sea cucumberA stressed or dead tiger tail sea cucumber can release toxins that harm fish; cover pump intakes.
Sea appleA stressed or dead sea apple can release toxins that harm fish; cover pump intakes.

Corals and anemones

Only the corals and anemones with a known risk are listed.

Take care (1)

Carpet anemones (Haddon's, giant)The carpet anemones (Haddon's, giant) can catch and eat small fish such as the purple firefish.

These checks follow the reasons fish and invertebrates clash: same species or genus, similar shape, mouth size, temperament, food, burrows, tank size and the order they are added. Individual animals differ; every source agrees on that.

Quarantine and health

Standard.

New fish are the most common way disease gets into a reef tank. Quarantine every fish in a separate tank before it joins the display, and choose a method that suits its tolerance of copper.

Captive-bred or wild?

Wild-caught mostly.

What does it cost in the UK?

about £40. This is one UK retailer’s listing on 21 October 2026, not a market average, and every item was sold out on that day.

Sources

LiveAquaria (US retailer) care sheetRead 21 October 2026, read in full. Used for: stats.
FishBase species summaryRead 21 October 2026, read in full. Used for: max length, IUCN.
Kraken Corals (UK retailer) catalogueRead 21 October 2026, read in full. Used for: UK price.

Last checked 21 October 2026. How we check

Found a mistake? Tell us how to fix it.