Helfrichs’ Dartfish (Nemateleotris helfrichi)

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Helfrichs’ Dartfish
Nemateleotris helfrichi
Helfrichs’ Dartfish (Nemateleotris helfrichi)
Name Helfrichs’ Dartfish
Name Lat. Nemateleotris helfrichi
Family Gobies
Family lat. Gobiidae
Order Gobies
Order lat. Gobiiformes
Origin Western Pacific
Habitat Rocky reefs
Diet Planktivore
pH 8.1-8.4
Hardness 8-10 °KH
Behavior Peaceful
Keeping Pair
Reef Compatible Yes
Care Level Difficult
Life Span 3-5 years
Protection No
Metric Units
Size 6 cm
Temperature 23-28 °C
Salinity 33-36 ‰
Aquarium ~ 200 l
US Units
Size 2.4"
Temperature 73-82 °F
Salinity 1.020-1.025 sg
Aquarium ~ 50 gal

Distribution and habitat

Nemateleotris helfrichi are widely distributed in the tropical Pacific Ocean, from Indonesia to the Tuamoto Islands and from the Ryukyu Islands to New Caledonia. They usually live in pairs in the sandy, boulder-rich zones of heavily circulated reefs below 40 m depth.


They need a well-structured aquarium with a reef structure (caves, crevices), with live rocks that they can graze on and that act like a biological filter, and deep, free sandy areas

Only lime-rich, heavy metal-free sands, gravels, stones or sea sand of various grain sizes may be used as substrate

Filters, skimmers and heaters are necessary to ensure water quality, as well as pumps to simulate tides, swells and bottom currents. Lighting must correspond to the species-appropriate day-night rhythm of the animals

Salinity: 33-36 ‰ pH value: 8.1-8.4
Carbonate hardness: 8-10 °KH Nitrate content: 2-8 mg/l
phosphate content: 0.01-0.1 mg/l nitrite content: 0.0-0.05 mg/l

For salinity, an average value should be aimed for, which may only vary slightly by +/- 0.5 ‰. Ammonia and ammonium must not be measurable. Special attention must be paid to constantly good water quality.


In nature they feed mainly on zooplankton. The feed change usually succeeds without problems. The food supply should consist of a commercially available, vitamin-enriched frozen special food mix for plankton eaters or a combination of live and frozen food, such as small mysis, krill, bosmids and artemia, as well as live cyclops, which also serve to keep them occupied. High-quality flake and granulated food is also often accepted after an acclimation period

It is recommended to feed small portions several times a day. Regular and varied feeding promotes health and increases resistance.

Behaviour and compatibility

They are monogamous and should be kept in pairs. Within the species they occasionally behave territorially. Keeping several pairs is only recommended in a larger and richly structured tank. Towards other fish they behave peacefully. They should only be socialized with other calm and peaceful fish, as they are very susceptible to stress.

Sex dimorphism

There are no known external distinguishing characteristics.

Reproduction and breeding

There are no known reports of successful breeding in the aquarium.


At night or in case of danger they retreat into self-dug caves under stones or coral blocks, accordingly the reef construction must be well secured. Suitable caves are e.g. stones lying hollow on the sand

Since they are very skittish and like to jump, the aquarium should be well covered.

If different species are kept together, care should be taken to ensure that the fish match each other in terms of water quality and temperature requirements, as well as their social behavior, and that the setup meets the needs of all species kept together. New fish to be introduced must be acclimated slowly to the water in the aquarium

Further literature can be found in your pet store.


Text: Werner Winter; Image: Franz Lowak

Source: KUITER, DEBELIUS (2007): Atlas der Meeresfische: Die Fische an den Küsten der Weltmeere, Kosmos Verlag; BAENSCH & DEBELIUS (2006): Meerwasser Atlas Bd. 1, Mergus Verlag; ENGELMANN (2005): Zootierhaltung - Tiere in menschlicher Obhut: Fische, Verlag Harri Deutsch

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