QUICK STATS

Care Level: Moderate
Diet: Carnivore / Planktivore
Temperament: Peaceful
Reef-Safe: Yes
Approximate Purchase Size: 2-4"
Approximate Max Size: Around 5"
Recommended Tank Size: 30 Gallons or Larger

BLUE GUDGEON GOBY

The Blue Gudgeon Goby, also commonly called the Blue Gudgeon Dartfish or Blacktail Dartfish (Ptereleotris heteroptera / Ptereleotris microlepis), is a peaceful reef-safe fish known for its slender body, soft blue coloration, dark tail marking, and graceful hovering swimming style.

Unlike many gobies that spend most of their time sitting directly on the sandbed, Blue Gudgeon Gobies are more active in the water column. They often hover near rockwork, sand, or burrow entrances and quickly dart into shelter when startled. Basically, a beautiful little blue fish with the reflexes of someone who heard a noise in the basement.

This species does best in peaceful community aquariums with stable water quality, open swimming space, and plenty of hiding places. They are generally reef-safe and should not bother corals or common invertebrates. They may be kept singly, in pairs, or sometimes in small groups in larger aquariums with enough space and shelter.

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

AQUARIUM REQUIREMENTS

AQUARIUM SIZE

A minimum tank size of 30 gallons or larger is recommended for a Blue Gudgeon Goby. While they are not bulky fish, they are active hoverers and benefit from both open swimming room and secure hiding spaces.

For pairs or small groups, a larger aquarium is strongly preferred. More space helps reduce stress, gives each fish room to retreat, and makes the whole “peaceful group fish” idea less dependent on wishful thinking.

HABITAT RECOMMENDATIONS

Blue Gudgeon Gobies do best in established aquariums with open swimming space, rockwork, and access to safe hiding areas.

Aquascaping: Provide a mix of open swimming space and live rock with caves, ledges, and crevices. These fish often stay near shelter and retreat quickly when startled.

Substrate: Sand or fine aragonite is recommended. Blue Gudgeon Gobies may use burrows or low shelter areas, so a softer substrate is preferred.

Rockwork: Live rock is useful for shelter, territory, biological filtration, and overall security. Multiple hiding places are especially helpful if keeping more than one.

Tank Maturity: A mature aquarium is preferred. Stable biological filtration, consistent water quality, and an established food routine will help reduce stress.

Tank Cover: A tight-fitting lid is strongly recommended. Blue Gudgeon Gobies are known jumpers, because apparently the aquarium itself was not enough of a life plan.

WATER PARAMETERS

Blue Gudgeon Gobies are generally hardy once established, but they still need clean, stable marine conditions. “Peaceful dartfish” does not mean “immune to chaos,” even though the hobby does enjoy testing that theory.

Temperature: 72-78°F
pH Level: 8.1-8.4
Salinity: 1.020-1.025 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 movement to keep the aquarium oxygenated and move waste toward filtration, but avoid extremely strong direct flow that makes the fish struggle to hover comfortably.

DIET

Blue Gudgeon Gobies are carnivorous planktivores that naturally feed on small drifting foods such as zooplankton and tiny crustaceans. In aquariums, they should be offered small, frequent meals that are easy for them to catch in 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 foods can help provide a balanced diet once the fish is eating reliably.

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 small plankton-sized foods can help support natural feeding behavior. Larger chunky foods may be ignored because this fish is built more like a delicate hover noodle than a seafood disposal unit.

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 Blue Gudgeon Goby before faster tank mates inhale everything like tiny aquatic vacuum cleaners.

COMPATIBILITY

Blue Gudgeon Gobies are peaceful and work best in calm community reef aquariums. They should be housed with tank mates that will not harass, chase, or outcompete them too aggressively for food.

COMMON TANK MATES

Fish: Clownfish, cardinalfish, peaceful wrasses, firefish, gobies, blennies, chromis, peaceful dwarf angelfish, tangs in larger aquariums, and other calm community fish.

Avoid: Aggressive damsels, dottybacks that may harass them, large predatory fish, aggressive wrasses, triggers, groupers, lionfish, and any fish likely to bully or eat them.

Same Species: Blue Gudgeon Gobies can sometimes be kept in pairs or small groups, especially in larger aquariums with plenty of hiding places. Monitor for chasing or stress.

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

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

BEHAVIORAL NOTES

Temperament: Peaceful and shy to moderately visible once established.

Swimming Style: Often hovers in the water column near shelter rather than perching directly on the bottom like many gobies.

Startle Response: Quick to retreat into rockwork or burrows when frightened. This is normal behavior, not a dramatic personal insult, though it may feel like one after you paid for the fish.

Group Keeping: May do well in pairs or small groups in larger, peaceful aquariums. Provide multiple hiding spots to reduce stress.

Reef Compatibility: Excellent for reef tanks. They generally ignore coral and invertebrates.

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

Burrow/Shelter Use: May use rock crevices, low caves, or burrow-like spaces for security.

Jumping: A tight-fitting lid is strongly recommended. Dartfish are excellent jumpers and apparently believe gravity is a negotiable concept.

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.