QUICK STATS

Care Level: Easy
Diet: Carnivore / Planktivore
Temperament: Peaceful, Shy
Reef-Safe: Yes
Venomous/Toxic: No
Approximate Purchase Size: 1.5-2.5"
Approximate Max Size: Around 3-3.5"
Recommended Tank Size: 20 Gallons or Larger

PURPLE FIREFISH GOBY

The Purple Firefish Goby (Nemateleotris decora), also known as the Purple Dartfish or Decorated Firefish, is a peaceful reef-safe fish known for its pale body, vivid purple to magenta tail, yellow facial tones, and tall elegant dorsal fin. It has a graceful hovering swimming style and adds bright color to reef aquariums without acting like it owns the entire water column.

Purple Firefish Gobies are popular because they stay small, are generally hardy, and work well in peaceful reef aquariums. They often hover just above the rockwork or sandbed, facing into the current while waiting for tiny foods to pass by. When startled, they quickly dart into a cave or hiding place, because apparently the correct response to movement is full emergency retreat.

This species is considered reef-safe and should not bother corals or most invertebrates. It does best with calm tank mates, stable water quality, and plenty of hiding places. Purple Firefish are peaceful, but they may become territorial toward other firefish unless kept as a bonded pair.

Note: Image is a representation of what to expect. The fish you receive may vary slightly in size, color, markings, fin length, and overall appearance.

AQUARIUM REQUIREMENTS

AQUARIUM SIZE

A minimum tank size of 20 gallons or larger is recommended for a Purple Firefish Goby. While some individuals may do well in smaller nano aquariums, a 20-gallon or larger system provides better water stability, more swimming room, and more space for hiding areas.

For pairs or community tanks, a larger aquarium is preferred. Purple Firefish are peaceful, but they can be shy and easily stressed by cramped spaces, aggressive tank mates, or chaotic aquascapes built by people who apparently fear empty swimming room.

HABITAT RECOMMENDATIONS

Purple Firefish Gobies do best in established aquariums with live rock, open swimming space, and secure hiding places.

Aquascaping: Provide live rock, caves, crevices, overhangs, and open areas for hovering. Firefish need shelter they can retreat into quickly when startled.

Substrate: Sand or fine aragonite is recommended, though they do not sift sand like sleeper gobies. They may use low caves, burrow-like spaces, or rock openings for security.

Rockwork: Live rock is strongly recommended. It provides shelter, territory, biological filtration, and natural surfaces around which the fish can hover and feed.

Tank Maturity: A mature aquarium is preferred. Stable water quality and an established feeding routine help reduce stress and improve long-term success.

Tank Cover: A tight-fitting lid is absolutely required. Purple Firefish are expert jumpers, because apparently the top of the aquarium looks like an exit interview.

WATER PARAMETERS

Purple Firefish Gobies are generally hardy once established, but they still need clean, stable marine conditions. “Easy” does not mean “compatible with water-quality crimes,” despite what the hobby keeps attempting in small tanks.

Temperature: 72-78°F
pH Level: 8.1-8.4
Salinity: 1.020-1.026 specific gravity
Ammonia, Nitrite, and Nitrate: Ammonia and nitrite should remain undetectable. Nitrate should be kept as low as reasonably possible, ideally below 20 ppm.
Water Flow: Low to moderate flow is ideal. Provide enough water movement to keep the aquarium oxygenated and move food through the water column, while still allowing calmer areas near rockwork for resting and hovering.

DIET

Purple Firefish Gobies are carnivorous planktivores that naturally feed on small drifting foods such as zooplankton, copepods, and tiny crustaceans. In aquariums, they should be offered small meaty foods that are easy to catch from the water column.

PRIMARY DIET

Frozen Food: Offer mysis shrimp, enriched brine shrimp, cyclops, marine blends, and other appropriately sized frozen foods. We at Summit City Coral prefer frozen foods such as LRS Reef Frenzy and PE Mysis.

Prepared Foods: High-quality small marine pellets, flakes, and prepared carnivore or omnivore foods can help provide a balanced diet once the fish is eating reliably. Smaller pellet sizes are best.

Live Foods: Copepods, amphipods, live brine shrimp, and other small live foods can help encourage feeding, especially in newly introduced or shy individuals.

Small Meaty Foods: Finely chopped marine foods and plankton-sized foods can help support natural feeding behavior. Avoid overly large foods unless you enjoy watching a tiny dartfish analyze dinner like it has been assigned a geometry proof.

FEEDING FREQUENCY

Feed small amounts 1-2 times per day, or 2-3 times per day for new, shy, or thinner individuals. In community tanks, make sure food reaches the Purple Firefish before faster tank mates inhale everything like aquatic tax collectors.

COMPATIBILITY

Purple Firefish Gobies are peaceful and work best in calm community reef aquariums. They should not be housed with aggressive or overly boisterous tank mates that may chase, intimidate, or outcompete them.

COMMON TANK MATES

Fish: Clownfish, cardinalfish, peaceful gobies, blennies, small peaceful wrasses, chromis, dwarf angelfish, and other calm community reef fish.

Avoid: Aggressive damsels, aggressive dottybacks, large predatory fish, aggressive wrasses, triggers, groupers, lionfish, hawkfish large enough to eat them, and any fish likely to bully or swallow them.

Same Species: Best kept singly unless kept as a bonded pair. Multiple Purple Firefish may fight or chase each other in smaller aquariums.

Other Firefish: Use caution when mixing with other firefish or dartfish species unless the aquarium is large enough and each fish has room to establish space.

Invertebrates: Safe with cleaner shrimp, hermit crabs, snails, urchins, and most common reef invertebrates.

Coral: Purple Firefish Gobies are considered reef-safe and should not bother soft corals, LPS, SPS, zoanthids, mushrooms, clams, or anemones.

BEHAVIORAL NOTES

Temperament: Peaceful and shy. Best kept with calm tank mates.

Hovering Behavior: Often hovers above the sandbed or near rockwork while facing into the current and waiting for small foods.

Startle Response: Quickly darts into rockwork or hiding places when frightened. This is normal behavior, not the fish being dramatic, although it is absolutely theatrical.

Reef Compatibility: Excellent for reef aquariums. They generally ignore corals and invertebrates.

Pairing: Can sometimes be kept as a bonded pair. Avoid mixing multiple individuals randomly in smaller tanks due to possible aggression.

Feeding Risk: Shy individuals can be outcompeted by faster or more aggressive feeders. Watch body condition and make sure they are getting enough food.

Dorsal Fin Display: The tall dorsal fin may be raised or flicked as the fish hovers, adding to its elegant dartfish appearance.

Coloration: Typically shows a pale front body with purple, magenta, yellow, and red tones toward the rear fins and tail. Color intensity may vary depending on stress, lighting, diet, and maturity.

Jumping: A tight-fitting lid is mandatory. Purple Firefish are notorious jumpers and can launch through surprisingly small gaps, because apparently evolution forgot to include respect for flooring.

ACCLIMATION PROCESS

This acclimation method helps reduce stress by gradually introducing the fish to your aquarium’s temperature and water chemistry.

1. TURN OFF THE LIGHTS & ATO

Turn off aquarium lights to reduce stress. If you have an Auto Top Off system, switch it off before starting acclimation.

2. FLOAT THE BAG

Float the sealed bag in the aquarium for 15-20 minutes to allow the temperature in the bag to equalize with the tank.

3. OPEN BAG, ADD FISH TO CONTAINER

Carefully open the bag and transfer the fish and shipping water into a clean bucket or container.

4. ACCLIMATE USING TANK WATER

Add 1/4 cup of tank water to the container every 5 minutes for 40 minutes.

5. TRANSFER FISH TO AQUARIUM

Once acclimation is complete, gently transfer the fish into the aquarium using a net or specimen container. Discard the shipping water. Do not pour shipping water into your aquarium.

6. REFILL THE AQUARIUM WITH SALTWATER

You may need to replace the saltwater removed during acclimation with fresh mixed saltwater.