Related FAQs: Dartfishes, Dartfish 2, Dartfish Identification, Dartfish Behavior, Dartfish Compatibility, Dartfish Selection, Dartfish Systems, Dartfish Feeding, Dartfish Disease, Dartfish Reproduction, Related Articles: CA: Family Microdesmidae, the Worm- and Dartfishes by Robert Fenner and Anthony Calfo, The Fire Goby or Dartfish, Nemateleotris magnifica
Bob Fenner

            Of the few Dartfish (Family Microdesmidae) species used in the hobby, the Fire Goby is my hands (fins?) down favorite. Gorgeously colored, interesting behaviorally, and hardy when it’s needs are met, Nemateleotris magnifica is a great choice for peaceful FOWLR and reef systems.

            Most Dartfishes are too-easily lost by aquarists for simple mistakes. Many “jump out” for want poorly secured tops. Next largest cause of loss is likely stress, damage and outright predation by inappropriate tankmates; closely followed by a lack of nutrition or out-competition for foods. Here’s hoping that by reviewing this brief article, none of these will happen to your Darts.

Nemateleotris magnifica Fowler 1938, the Fire Goby. Indo-Pacific, eastern African coast to Hawai'i. To three and a half inches long. The most popular aquarium species. One in a typical pose in the Maldives... ready to dart back into its hole in the substrate, another single shot (almost always found in pairs) and a couple together in S. Sulawesi. http://fishbase.sinica.edu.tw/Summary/speciesSummary.php?ID=6629&genusname =Nemateleotris& speciesname=magnifica

Fire Gobies in the wild in Fiji and Wakatobi, S. Sulawesi, Indonesia

 

Distribution/Sources/Size: Indo-Western tropical Pacific. East Africa, Maldives, N. Australia, Indonesia and supposedly all the way over to Hawai’i, though I’ve never encountered it there. It is always found in areas of sandy bottom (where it burrows), and low current (that provide planktonic fare), from about twenty to one hundred thirty foot depths. Called “hover gobies” for their penchant for hanging over the bottom looking for floating zooplankton food and near bolt holes to escape predators.

This species grows to three inches length in the wild and in captivity.

 

Selecting/Stocking/Compatibility: Surprisingly, for a small fish that looks delicate, Fire Gobies ship well; and are either obviously “in bad shape” or fine and ready to go. This being stated, I would still ask to see the fish fed in front of me.

This Dartfish species lives mostly in pairs in the wild; though these pairs in turn may be appear to be associated with other duos nearby. Do provide at a minimum two square feet of bottom surface area per couple if you stock more than two.  It can be kept solitarily, and do fine, but for the most behavior repertoire, you want to have two. Be aware that if purchased individually the two you have may be incompatible and fight; with a need to be separated. Better by far for you to purchase as a compatible “pair” at your dealer.

Dartfish are the epitome of reef-safe, not picking on, nor consuming polyp-life in the least. They really only go after small worms, crustaceans et al. that are small enough to fit into their tiny mouths. Unfortunately the reciprocal is not so; and Lionfishes and their mail-cheeked kin, large wrasses, bigger basses and such will consume them if they can. There is some slip and slide concerning how much other fish life can go with them; more with bigger systems, more décor…

 

System: Some sources state that a mere ten gallon system will suffice to keep a pair of these fish, but I would not try them in anything under a twenty… and whatever sized vessel used, flatter rather than tall/show dimensioned.

            Substrate is VERY important; this species lives on sloped to flat mixed sandy and rubble zones on reef slopes; provide a similar mix of fine to larger sand, including broken coral pieces, with which they can dig and support their DIY underground burrows. Some folks go so far as to provide ready-made under-sand caves by sticking small lengths of PVC pipe (3/4”, schedule 40 is fine) in the substrate and/or at the rock/sand interface for their Dartfish to find and use.

            It bears repeating that this fish is an escape artist. Particularly for folks who use “open top” systems to accommodate metal halide lighting. You NEED to screen all openings to the top that are large enough to allow their exit; else your Dartfish may become carpet jerky.

           

Foods/Feeding/Nutrition: This fish is zooplanktivorous; needs a handful plus times offerings of live and/or frozen/defrosted meaty foods (Cyclops, Mysids, pods…), mashed commercial or DIY home-prepared food preparations. The very best arrangement is to have a large-as-possible tied in sump (refugium) with fine sand Deep Sand Bed (DSB), live rock and macro-algae culture.

            Dartfishes are eager eaters; if yours appear off-feed, do check for water quality issues.

 

Disease/Health: Gobioid fishes like the Dartfishes are not as susceptible to protozoan and infectious agents, but unfortunately, due to their size, are more sensitive to the usual remedies employed to combat them. Do take care if you find you need to utilize a metal or dye-based medication. In fact, often the balance of such incidences may be shifted to your fishes (and away from the biological disease agents) by simply improving environmental conditions and boosting their immune systems through the use of Vitamin and HUFA preparation soaking of foods.

 

Reproduction: This is a monogamous species, with pairs associated as stated above. As far as I know they cannot be sexed externally. Likewise I have not encountered any reliable information concerning the spawning/reproduction of this or any other Microdesmid species. I strongly suspect that this aspect of their biology is similar to other closely related Gobioid fishes.

 

Cloze: The Red Dart Goby is indeed a magnificent fish; sporting brilliant colors, bobbing here and there with its flickering dorsal fin. Provide yours with adequate space, substrate, regular meaty feedings and avoid overly-competitive/aggressive tankmates and you can have miniature show specimens that are delightful to observe.