Firefish Goby – Fire Dartfish

Fast Facts

Name: Firefish
Other names: Firefish Goby, Fire Dartfish
Scientific name: Nemateleotris magnifica
Size: Up to 3 inches (7.5cm)
Age: 10years or more
Appearance: Yellow, white, pinkish to orange-red, black-outlined dorsal, anal, and caudal fins
Food: Seafood, Brine or Mysis Shrimp
Temperature: 72-78° F (22.2-25.5° C)
pH: 8.1-8.4
Tank Size: 10 Gallons (40 L)
Natural Predators: Larger fish, including wrasses and bass
Sleep/wake cycle: diurnal
Salinity: 1.02-1.026

Nemateleotris magnifica

The Firefish (Firefish Goby) is a friendly, well-behaved saltwater fish that is an excellent

Nemateleotris magnifica
firefish, fire dartfish (Nemateleotris magnifica)

addition to a reef tank, especially one of smaller size. Bright and colorful and non-aggressive toward other fish, corals, or other reef tank dwellers, it’s hard to go wrong with a Firefish. They have long been a favorite among marine hobbyists.

 

These fish tend to burrow, a habit which, paired with their bright colors and laid back nature, can make them fun towatch for beginning and experienced hobbyists alike.

Native Habitat

Firefish are native to the waters of Africa, the Coral Sea, Indonesia, Maldives, and the Indo-Pacific Ocean. There is also speculation that they reside in Hawaiian waters, but the documentation is not conclusive.

They live in groups in the wild, hiding in various spots on a reef. While they will swim just above the reef, each fish has a designated “bolt-hole.” which they can dart if they feel threatened (hence their other name, “Fire Dartfish”). Their natural diet is plankton, which they eat as it flows through the water. In captivity, they will still want to eat food that is moving, which is something their keepers should keep in mind, especially if feeding non-live food.

Firefish tend to be fairly hardy, with the only apparent issue being whether or not they will eat enough if there are more aggressive fish in the tank. Their natural instinct is to stick close to their reef and to hide in their bolt-hole at the slightest sign of danger or stress, and that instinct carries over into life in captivity.

Characteristics

fire dartfish tend to hide when they’re startled, and this includes when first introduced to a new tank. The fish can be so good at hiding that some owners will think the fish is dead somewhere in the tank. However, once it feels more comfortable, it will come out for food along with all the other fish. Firefish tend to remain relatively docile in comparison to other reef fish, and will not display aggression toward any other breed except their own. While this can be great when you are searching for a fish who will get along well with other fish, it does mean that Firefish run the risk of having all their food snatched away by more aggressive fish. Therefore, owners should be sure to watch their Firefish to ensure they receive enough to eat.

Due to their general timidity, it can be problematic to partner them with more aggressive types of fish such as wrasses and angelfish. Larger or more aggressive species have even been known to try to eat Firefish in their tank.

Fire dartfish Aggression:

Firefish Goby Pairing
Firefish goby” pairing by Brenard Dupont licensed under CC BY 2.0

Fire dartfish will also become aggressive toward each other, and thus should either be kept as the only firefish in the tank or else mated with one other Firefish. Most experts find little to no observable difference between the sexes, so just getting two will be fine. You do not need to worry about getting a specifically male and female pair.

If kept in groups of more than two in a small tank, your dartfish will become very aggressive and eventually kill each other off. Some report success with groups of fire dartfish in a large aquarium, but most experts recommend no more than two at a time.

Coloring

Most Firefish have a torpedo shaped body that is either white or yellow in the front. Their color fades into various shades of red or orange as you go toward the tail. The tail and dorsal and anal fins are outlined in black. There is, however, a purple variety (Nemateleotris decora) that is more rare and expensive than the standard dartfish.

Nemateleotris magnifica
Nemateleotris magnifica” side profile by zsispeo licensed under CC BY 2.0

They typically have seven dorsal fins, 28 to 32 dorsal soft rays, one anal spine fin, and 27 to 30 anal soft rays.

If you do have a pair, watch for them to communicate with each other. they tend to use their dorsal fin (the longer, pointed one) to talk.

Firefish Care

Firefish are carnivores and thus require a meat diet. Consider feeding them foods such as Mysis Shrimp, chopped seafood (fresh or frozen), or Brine Shrimp. They will also feed on the algae and zooplankton in the aquarium (another good reason to have plenty of rocks and other surfaces on which algae can grow). They may even pick through the substrate.

Your Firefish can also eat chopped crustaceans or prepared foods as well. Live food is generally the best option, but if you choose to go with a dead or prepared food, just change the water filter capacity until the food appears to move. Firefish are used to eating moving food (either brine or moving plankton), so be sure to mimic that environment, whatever you choose to feed.

Firefish have relatively small stomachs, so it is best to feed them twice daily to ensure they receive enough nutrients. Feeding them a wider variety of food can aid in overall health as well as in keeping their colors vibrant. Firefish that do not get an adequate variety of vitamins and minerals will begin to lose their vibrant colors.

Tanks

Firefish can thrive in tanks as small as ten gallons, although many recommend a tank that

is closer to 25 gallons or more. A wider tank tends to be better than a deep one, but make sure there is enough depth to allow for a deep enough substrate for your Firefish to burrow into as it creates its bolt-hole. Also, the Firefish do have a reputation for jumping out of the water when startled, so having a tank with a covered top is imperative. Even small openings (such as for feeding) should either have a cover or at least a screen. Otherwise, you will probably come home to a Firefish on the floor rather than in the tank. Also, be sure that the cover fits tightly, as they may be able to knock it off otherwise.

Ideal Aquarium setup
Ideal aquarium setup for Firefish gobies with lots of live rock and sand by timmers99 licensed under CC BY 2.0

Hiding places are important:

They also need to have places to hide, so hiding rocks or other hiding places will make it feel the most secure. They are more likely to create a hole in which to hide than they are to adapt to one created for them, so be sure to allow for plenty of options. Be sure there is plenty of substrate in the bottom of the tank, even if you have provided other hiding places. It is very likely that your Firefish will opt to dig its bolt-hole rather than simply using what you have provided. Also, it is worth noting that if you do have a pair of Firefish, they will not share hiding places or bolt-holes, so make sure there are adequate hiding areas for each of them.

Tank temperature should stay in the 72-78F (22-26° C) range.

Choosing a Firefish

Fire dartfish are not always caught using the best practices. therefore, it is important to purchase from a reputable source and to check the fish before buying. The Firefish’s head should angle upward, not downward. They should also be willing to eat and should exhibit signs of overall healthy swimming. Firefish do tend to either be completely fine or else obviously sick, but it is still a good idea to observe the fish both swimming and eating before deciding to purchase.

When you first bring your fish home, remember that it will most likely hide until it acclimates to its new home. It can be helpful to keep the tank in a dimly lit area while your Firefish adjusts to its new home. An alternative could be covering the tank for the first day or so, just to give your darkfish a sense of security as it acclimates. Be sure to have hiding places available to your Firefish as soon as you introduce it to its new tank.

If a lot of time goes by and you are still not seeing your Firefish, you may want to consider whether other, more aggressive members of your tank may be keeping the Firefish frightened in its hole.

Fire Dartfish Breeding

Firefish tend to be very difficult to sex, although some sources indicate the females are smaller and thinner than the males. At this point, there is no reliable method to sex your fish.

It is also very rare for them to spawn in captivity, and there is little data regarding egg size or the practices involved in mating or their care of eggs once they are laid. On the rare occasion that breeding is reported, the details vary significantly between reports. They are thought to breed in monogamous pairs.