Firefish Goby
Nemateleotris magnifica
Slender dartfish with a flicking dorsal flagBeginner
- Lifespan
- 3-5 years
- Size
- 7-8 cm (3 in)
- Social needs
- Singly or bonded pair; nervous in groups
- Time
- Daily feeding; weekly testing/changes
- Cost
- Medium
- Diet
- Carnivore (mysis, brine, zooplankton, pellets)
Overview
What is this animal?
- The Firefish is a slender dartfish, pale at the front fading to fiery orange-red at the tail, with a tall first dorsal fin it flicks like a flag.
- Despite the common name it is a dartfish rather than a true goby.
- Peaceful, reef-safe, and hardy, it is a good beginner fish.
- It is timid and easily startled, hovering above the rockwork and darting into a burrow at any threat.
- Given calm tankmates and secure hiding holes, it becomes a graceful, ever-present swimmer that adds movement to the mid-water zone.
Temperament
- Peaceful, shy, and reef-safe, the Firefish hovers above the rocks and dives for cover when startled.
- It poses no threat to corals or invertebrates and is easily intimidated by pushier fish.
- Keep one per tank or a known bonded pair, as two unbonded individuals usually fight.
- It does best with equally gentle tankmates such as small gobies and cardinalfish, where it gains confidence and stays out in open water.
A good fit for
- Beginners wanting graceful movement
- Peaceful nano and community reefs
- Reef-safe stocking plans
- Keepers with a securely covered tank
Common mistakes to avoid
- Any open gap in the lid - they jump out
- Housing with aggressive tankmates
- Keeping two unbonded individuals (fighting)
- No burrows leaves them stressed and hidden
Enclosure
Minimum 75 litres (20 US gallons)
Fine alone or with company. Singly or bonded pair; nervous in groups
- A cycled 75L (20 gal) tank with rockwork providing several burrow-like crevices suits a single fish.
- Keep salinity 1.024-1.026, temperature 23-26°C (74-79°F), pH 8.1-8.4, and nitrate low.
- A tight, gap-free lid is essential because Firefish are accomplished jumpers.
- Provide multiple crevices so it always has a refuge within reach, which helps it feel secure and stay visible.
- House it only with peaceful tankmates, as boisterous fish keep a Firefish permanently hidden, stressed, and reluctant to feed.
Supplies
Setup
- Tank, stand and sump
- Return pump and powerheads
- Protein skimmer
- Reef lighting
- Rock and sand
- Salt mix, refractometer and test kits
- Quarantine tank
Ongoing
- Frozen mysis shrimp
- Frozen enriched brine shrimp
- Frozen cyclops
- Micro marine pellets
- Copepod bottle or refugium culture
- Turkey baster or pipette for target-feeding
- Small thawing cup and fine strainer
Safe substrate: Aragonite sand · Dry or cured live rock · Bare bottom
Care routine
Daily
- Check salinity, temperature and flow
- Check the lid and every gap
- Feed
- Head-count and look everyone over
- Top up evaporation with fresh water
Weekly
- Service the skimmer and filter socksevery 3 days
- Clean the glass
- Test the water
Monthly
- Water changeevery 2 weeks
- Calibrate the refractometer
- Check salt, RO/DI and reagents
- Replenish sand-bed life
Less often
- Deep-clean pumps and powerheadsevery 3 months
- Replace RO/DI filter mediaevery 6 months
Vet: Quarterly review with a lid check — every 3 months
Top resources for more info
Independent creators and organisations we would send a friend to. We have no affiliation with any of them, and nothing here is sponsored. Links checked 2026-09-19.
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Diet
- The Firefish is a micro-carnivore that picks zooplankton from the water column.
- Offer frozen mysis, brine shrimp, finely chopped seafood, and small marine pellets, fed once or twice daily in modest amounts.
- Most accept prepared foods quickly once settled, though shy individuals feed better when tankmates are calm.
- Small, frequent feedings suit its natural picking behaviour.
- A varied diet maintains its tail colour and overall condition.
Health
- Firefish are generally hardy but sensitive to stress and poor water quality.
- The leading cause of death is jumping out of the tank, not disease, so a sealed lid is the single most important health measure.
- They can develop marine ich or bacterial infections if stressed by aggressive tankmates or unstable conditions.
- Quarantine new fish, keep nitrate low, and provide a calm environment.
- A secure, peaceful tank lets a Firefish reach its full lifespan.
Is your enclosure big enough?
Is this urgent?
In a reef, stability matters more than any single target number. A parameter moving fast does more damage than a parameter sitting slightly off.
Go now
Today
Quarantine every new animal, including corals and inverts. It is the single practice that separates a reef that lasts from a reef that restarts.
This is general guidance for a healthy adult, not a diagnosis. An exotics vet who knows your animal always overrides it — and the time to find one is before you need one.
What it really costs
Setup, monthly, first year and across a whole life, itemised and with the electricity worked out from the actual wattage. Published figures for the same animal disagree by a factor of four, so the calculator shows ranges rather than picking one.
Bedding and substrate
In a marine system the rock and the sand are life support, and how you start them decides the first six months.
Safe
With a caveat
Never
This is our general list for saltwater fish. We have not built one specific to Gobies yet.
My kit says 0.25 ppm. Is that dangerous?
A liquid kit measures total ammonia, but only the un-ionised fraction is really toxic, and that fraction is governed by pH and temperature — each whole pH unit multiplies it roughly tenfold. So the same reading can be nearly harmless in one tank and lethal in another; this works out which one you are in.
Compare with other animals
The same axes for every animal, side by side — the way the guides are written makes that a fair comparison rather than two articles.
Gobies, side by side
Same axes, same care guides — the honest way to choose between types.
See all Gobies side by side →
