By Hektor Jorgo
The firefish goby (Nemateleotris magnifica) is one of the most visually striking small fish available for reef and community tanks — a slender, hovering fish with a fiery red-orange rear half, a pale front half, and a tall, flag-like dorsal fin it flicks constantly. It's peaceful, reef safe, and easy to feed. It also has one notable quirk that every prospective owner should know about before buying: firefish are prolific jumpers, and an open-top tank is a real risk to their safety.
Appearance and Behavior
Firefish have an elongated body, pale cream-to-white on the front half transitioning to a vivid red-orange on the rear half and tail. The first dorsal fin is tall and dark-edged, and is raised and lowered almost constantly — thought to be both a communication signal to other firefish and a startle response.
They're generally shy, spending most of their time hovering near a chosen burrow or rock crevice, darting in tail-first at the slightest disturbance. Over time, in a tank without aggressive tank mates, firefish become bolder and will hover further out in open water — but they never fully lose the instinct to dive for cover.
Tank Requirements
Tank Size
A single firefish can be kept in a tank as small as 10-20 gallons (38-75 liters). They're not active swimmers in the sense of needing long swimming lanes — what they need is a secure burrow/crevice and, critically, a covered top or sufficient water-line clearance (see jumping risk below).
Aquascaping
Firefish need rockwork with at least one crevice or burrow they can retreat into tail-first — this is their primary security behavior and without it they tend to stay stressed and hidden. Sand substrate is appreciated, as some individuals will dig small burrows at the base of rockwork, though this isn't strictly required if rock crevices are available.
Water Parameters
| Parameter | Target Range |
|---|---|
| Temperature | 72-78°F (22-26°C) |
| Salinity | 1.020-1.025 SG |
| pH | 8.1-8.4 |
| Ammonia / Nitrite | 0 ppm |
| Nitrate | <20 ppm |
| Alkalinity | 8-12 dKH |
Firefish are reasonably hardy once settled but are more sensitive to being chased or stressed than tougher species like damselfish — stress-related health decline is more common in firefish than outright water-quality intolerance, which is part of why tank mate selection matters so much (see below).
Diet and Feeding
Firefish are primarily carnivorous, feeding on zooplankton in the wild. In the aquarium, offer:
- Frozen mysis shrimp (a staple — firefish often prefer this over flake)
- Frozen brine shrimp, enriched
- High-quality marine pellet small enough for their mouth size
- Finely chopped meaty foods occasionally
Feed 1-2 times daily. Because firefish are often shy feeders, especially when newly introduced or housed with boisterous tank mates, it's worth observing feeding directly to confirm they're getting enough — a firefish that's losing the competition for food at feeding time will decline slowly rather than obviously.
The Jumping Risk — What You Actually Need to Know
This is the single most important practical consideration for keeping firefish, and it's not exaggerated:
- The trigger is usually a startle response — sudden movement near the tank, a light turning on abruptly in a dark room, being chased by a tank mate, or a loud noise/vibration.
- The escape route is straight up. A firefish that bolts for cover in an open-top tank can clear the water line and land outside the tank, on a sump cover, or on the floor.
- Mitigation is straightforward: a tight-fitting lid, a screen/mesh cover over any open areas (overflow boxes, gaps around plumbing), or — in open-top tanks — maintaining enough distance between the water line and the tank rim that a startled fish's jump arc doesn't clear it (this is less reliable than a physical cover).
This single fact disqualifies firefish from being a good choice for fully open-top tanks without modification, but makes them an excellent choice for any tank with a hood, canopy, or screen top.
Tank Mates and Compatibility
Firefish are peaceful and do best with similarly calm tank mates. They can become stressed — and stop eating — when housed with:
- Fast, aggressive feeders that out-compete them at every meal
- Larger semi-aggressive fish that chase or nip at them (this also compounds the jumping risk)
Good tank mates include the common clownfish, gobies, blennies, and most peaceful community fish. The yellowtail damselfish can work but should ideally be added after the firefish is established, since damselfish added later tend to be the more dominant party — the reverse order (firefish added to a tank with established damsels) increases stress on the firefish.
The mandarin fish is another peaceful, slow-moving species that's often considered alongside firefish for a calm reef community — both do best without fast, food-competitive tank mates, though the mandarin's feeding needs are far more demanding than anything required here.
Keeping pairs: A bonded pair, or two similarly-sized juveniles introduced together, can coexist peacefully and may even spawn in a mature tank. Mismatched introductions (one resident, one new) often result in aggression from the resident fish.
Common Health Issues
- Stress-related decline — more often the root cause of health problems in firefish than direct water-quality intolerance. Symptoms include prolonged hiding, loss of appetite, and faded color.
- Marine ich — as with other marine fish, primarily a risk from unquarantined tank mates.
- Injury from jumping attempts — even non-fatal jumps (where the fish lands back in the tank, on the substrate, or against the lid) can cause scrape injuries or secondary infections.
Quick Setup Checklist
- Tank: 10-20+ gallons with a secure lid, canopy, or mesh cover
- Rockwork with at least one crevice/burrow for retreat
- Salinity 1.020-1.025, temperature 72-78°F
- Frozen mysis/brine as dietary staple, fed 1-2x daily
- Add alongside (not after) more boisterous tank mates, or pair two similarly-sized individuals together
