Why is the Helfrich's Firefish so expensive compared to other firefish?

They are collected at much greater depths (often 40-90 metres) than common firefish, which requires divers to use specialised equipment like rebreathers, significantly increasing collection risks and costs.

Can I keep multiple Helfrich's Firefish in the same tank?

Unless they are a confirmed, bonded male and female pair, keeping more than one in a standard aquarium will almost certainly result in territorial fighting until only one survives.

Why is my firefish hiding all the time?

Dartfish are naturally timid. If housed with fast, aggressive, or large tankmates, they will remain in their bolt holes. Ensure the tank is peaceful, lighting isn't excessively harsh, and that no other fish is harassing it.

Will a Helfrich's Firefish eat my ornamental shrimp or corals?

No. They are 100% reef safe and strictly planktivorous. They will ignore your corals, cleaner shrimp, and hermit crabs entirely.

Do I need a deep sand bed to keep them?

While related to gobies, firefish do not usually dig their own burrows. They prefer to use existing crevices in live rock or rubble at the base of the aquascape. A deep sand bed is not strictly necessary as long as adequate bolt holes are provided.

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Helfrich's Firefish

Nemateleotris helfrichi

A stunning, deep-water dartfish famed for its vivid purple-to-yellow gradient, demanding a secure aquarium lid and peaceful tankmates.

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Ideal Conditions

Temperature: 22 – 26 °C
pH range: 8.1 – 8.4
Hardness: 14 – 22 dGH
Salinity: 1.023 – 1.026 SG
Adult size: 5 – 7 cm
Nano reef or larger: 75 litres+
Lifespan: 3 – 5 years
Diet: Carnivore
Water flow: Moderate
Preferred setup: Live rock with numerous caves, overhangs, and bolt holes. Tight-fitting lid is mandatory.

About the Helfrich's Firefish

Helfrich's Firefish is arguably the most coveted of all the dartfishes, commanding a high price due to the significant depths at which it is collected. Recently, taxonomists split the fish historically traded under this name into two species: the true *Nemateleotris helfrichi* (endemic to French Polynesia) and the newly described *Nemateleotris lavandula* (the Lavender Dartfish, found across the wider Pacific). In the aquarium hobby, both are still routinely sold as Helfrich's Firefish and share identical care requirements. They are exquisite, slender fish featuring a striking purple face that gives way to a pale, pastel-yellow or white body, capped by an elongated, flicking dorsal fin.

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Is it right for your tank?

Check Helfrich's Firefish against a habitat you already keep. We compare water type, temperature, pH, adult size, group needs and everything living there.

Where Helfrich's Firefish comes from

Native range

French Polynesia, Tuamotu Archipelago, Marquesas Islands, Society Islands

Countries / regions

French Polynesia

Habitat

Deep outer reef slopes, drop-offs, and rubble patches at the base of vertical walls.

A 2023 taxonomic revision split the widely distributed western/central Pacific populations into a new species, Nemateleotris lavandula. True N. helfrichi is restricted to French Polynesia.

Similar species

Lavender Dartfish
Nemateleotris lavandula
Purple Firefish
Nemateleotris decora
Fire Goby
Nemateleotris magnifica

We’re adding more full species guides as the catalogue grows.

Compatible tank mates

Reviewed guidance based on this species' recorded traits.

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Ocellaris Clownfish
Amphiprion ocellaris
Peaceful, occupies a different territory, and will not intimidate the shy firefish.
Great
Tailspot Blenny
Ecsenius stigmatura
Small, peaceful benthic grazer that leaves the water column entirely to the dartfish.
Great
Purple Firefish
Nemateleotris decora
Congeneric species will fight fiercely in all but the largest, most intricately scaped aquariums.
Not recommended
Six Line Wrasse
Pseudocheilinus hexataenia
Highly active and potentially aggressive wrasses may intimidate the firefish, causing it to hide perpetually and starve.
Compatible with caution
Dwarf Lionfish
Dendrochirus brachypterus
Will easily swallow the slender firefish whole.
Not recommended

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