Helfrich's Firefish: A Rare Gem from a Familiar Family

Author: Philip Hunt

If firefishes were princesses, this species would arguably be the fairest of them all thanks to its exceptional coloration and ease of care.

Firefish Basics

The firefishes of the genus Nemateleotris have been marine aquarium favorites for many years. They are beautifully colored, peaceful toward other fishes (except, in most cases, other members of their own species), small enough to be easily housed in most aquariums, easy to feed, and not at all prone to disease. Firefishes pose no threat to invertebrates and are thus ideal for reef aquariums.

They are not completely without disadvantages, however. They are relatively shy and should ideally be kept with other fishes of similar temperament. If startled or chased by other fishes, they are likely to jump out of the aquarium, often finding surprisingly small gaps between the covers. Firefishes are such enthusiastic jumpers that great care needs to be taken even when adding them to the aquarium. If one were to leave the shipping bag open for a moment too long, the fish could take to the air like a missile. If you’re lucky it will land in the aquarium, albeit after an incomplete equilibration, but it’s just as likely to miss and end up on the floor.

There are currently three recognized species of Nemateleotris: the common or red firefish N. magnifica, the purple firefish N. decora, and Helfrich’s firefish N. helfrichi. N. magnifica is the one most commonly offered for sale and thus the most widely kept, and the least expensive. The purple firefish N. decora, while generally commanding a price two or three times greater than N. magnifica, is also quite a common aquarium resident, but for most marine hobbyists that’s all there is to say about firefishes. So what of the mysterious third species?

The Fairest of Them All?

Nemateleotris helfrichi is perhaps the most beautiful of all the firefishes, which is quite an accolade given the attractiveness of the other two species. Like the other firefishes, it has a color scheme that demands close inspection if it is to be fully appreciated. A fleeting glance will leave you with the impression of a very colorful fish, but the full, complex beauty only becomes apparent when you can take in all the details. Fortunately, this is easy to do in the right aquarium setting.

Once settled into the aquarium, firefishes are very rewarding to watch. Their habit of hovering in the water column allows very close observation, and unlike many aquarium fishes they tend not to start begging for food the moment their keeper approaches the tank. Provided you don’t make any sudden moves, you can watch from only a few inches away and really take in the remarkable color scheme of your firefish.


The basic body color of N. helfrichi is a pale lavender, which is quite unusual in a fish, making it immediately striking. The lavender color is deepest on the anterior part of the body and becomes paler towards the tail. The head is a bright golden yellow, similar to that of its more common cousin N. magnifica. On top of the head is a metallic purple triangle that runs to the base of the first dorsal fin ray; the base of this triangle spreads into the upper part of the eyes.

The front edge of the first dorsal fin ray is also pale blue. As in the other firefishes, the first ray of the dorsal fin is elongated. In N. helfrichi it is, relative to the fish’s size, longer than in N. decora, but nowhere near as long as that of N. magnifica. As in the other species, this fin is constantly flicking, possibly signaling in some way. The rear edge of the front part of the dorsal fin is orange.

The rest of the dorsal fin and the anal and caudal fins are all a soft primrose yellow that works very well with the lavender of the body. It’s a little like a more subtle version of the sharp purple-yellow contrast seen in the royal gramma Gramma loreto and the dottybacks Pictichromis paccagnellae and P. diadema. The dorsal and anal fins are both edged with the same bright golden yellow found on the head, and a thin purplish-blue stripe runs through the anal fin. Finally, the pelvic fins are the same pale yellow as the dorsal and anal fins, but tipped in velvety black. You can see how complicated the coloration of this species is by how long it takes to describe it!


Now, some fortunate keepers of this species may be thinking that this description doesn’t quite match their fish. Some individuals have no yellow on the head but a hint of metallic blue instead, and the dorsal and anal fins may be purple or pale blue rather than yellow. As relatively little is known about this species, it is unclear what these color variations represent. While subtle variations in fin color may be no more than geographical variations (the description provided here is for fishes from Micronesia, the most usual source for aquarium imports), it has been suggested that the form from the Cook Islands (with no yellow on the head, and blue dorsal and anal fins) may be a subspecies or even a completely different species.


In the wild this species is reported to be found close to the seabed over sand or rubble patches at the base of steep reef slopes, a habitat similar to that of other firefishes, but ranging to greater depths. It lives at depths ranging from 25 to 90 meters but is rarely found at less than 40 meters. The species is often found in pairs (and sometimes offered for sale as such) and is reportedly monogamous. It has been recorded in southern Japan (the Ryukyu and Ogasawara Islands), Micronesia (Pohnpei, Kosrae, the Marianas, and Palau), and Polynesia (Fiji, Tahiti, American Samoa, the Tuamotus, and the Cook Islands).

Aquarium Care

Helfrich’s firefish is straightforward to keep; there are only two key requirements: a well-covered tank (required for all firefishes) and companions of a peaceful disposition. Particularly problematic tankmates are other planktivorous species, especially those with more aggressive temperaments. These include Pseudanthias wreckfishes, Cirrhilabrus and Pseudocheilinus wrasses (the pajama wrasse P. hexataenia and its relatives), small benthic predators (i.e., damsels), and dottybacks. Even the most peaceful of the latter (such as Pseudochromis fridmani and P. springeri) can behave very aggressively toward firefishes.


Keeping firefishes with larger, more boisterous fishes such as tangs is a somewhat hit-and-miss business. These fishes are unlikely to pay any attention to firefishes, but although some firefishes get used to such companions, the most likely outcome is that the firefish will be intimidated by its heftier tankmates and you’ll seldom see it.

Better companions for N. helfrichi are other rather quiet species, such as small cardinals (i.e., the various Zoramia species, and the smaller of the Apogon and Archamia species), forktails (Assessor species), mandarins and scooters Synchiropus (assuming the tank is suitable for them), small gobies, and Meiacanthus fang blennies. Apart from members of their own genus—and particularly their own species, except in the case of mated pairs—firefishes get along very well with other members of the dartfish family (Microdesmidae), such as Ptereleotris species.

DÉcor and Feeding

Like all firefishes, N. helfrichi prefers to have shelter, in the form of rocks or caves, close at hand. The species is harmless to all invertebrates and is an ideal fish for a reef aquarium, although it may be wise not to house it with large predatory shrimps, such as Stenopus species. Feeding is also straightforward: frozen crustaceans of suitable size, such as Artemia or copepods (i.e., red plankton), finely chopped mysis or krill, and fish roe are good staple foods. Flake foods will also be taken provided they are broken into small-enough pieces and preferably presented in midwater, as firefishes sometimes have difficulty learning to feed from the surface.

Aquarium Requirements

As it is the smallest of the firefishes (growing to a maximum of 6 cm), N. helfrichi can be housed in nano-reef aquariums, although extra care needs to be taken with respect to companions in such small tanks. The lack of space may heighten the territorial instincts of many fishes. When I first acquired my Helfrich’s firefish, the aquarium I added it to (a 46-liter [12-gallon] nano tank) was already home to a pair of small, tank-bred common clownfishes Amphiprion ocellaris, as well as a clown goby Stonogobiops yasha.

Common clowns are generally pretty mild mannered, but I was distressed to see them attack the firefish. The small-tank setting presumably accentuated their slight territorial tendencies. Fortunately, the firefish didn’t attempt to jump from the tank but instead hid among the live rock. Its fins were badly shredded after a couple of days, however, and when I saw the female clown grab it by the tail and drag it across the tank, I knew it was time to act and removed the two clowns. As a testament to the hardiness of this species, its badly damaged fins recovered quickly to regain their former beauty. Since then, the firefish has shared its tank with the clown goby, a yellow forktail Assessor flavissimus, and a redheaded goby Elacatinus puncticulatus, the latter two fishes having been added more recently. These four fishes live peacefully together, and if anything the firefish is the dominant individual.

As a deep water species, N. helfrichi might be expected to prefer cooler and less brightly lit conditions than those typical of aquariums designed to house corals such as Acropora species. There have been reports of this species not faring well at high temperatures, and while it’s difficult to know how much credence to give to these (as with any rarely kept fish, the limited experience of husbandry makes it hard to assess the true requirements of the species), the depths it is encountered at in the wild do suggest that water slightly cooler than usual in the reef aquarium would be ideal. That said, my own Helfrich’s firefish has tolerated temperatures up to 29°C (84°F) for several weeks without problems. As far as lighting is concerned, it might be better not to house this species in tanks with 250- or 400-watt metal halide lamps, but under less extreme illumination.

A Rare Jewel

Given that this is such a beautiful and undemanding fish, why is it so little known? The answer lies in two factors that determine its price and availability to the aquarium trade: geographical distribution and the depths at which it usually lives. In terms of geography, its native range is away from the usual areas for aquarium trade collection. Add to this that it is rarely found at less than 40 meters deep, and you have a recipe for a rarely available, expensive fish that many enthusiasts may never see. Here in the UK, it is if anything even less commonly offered for sale than in the U.S. and commands higher prices. In many years of fishkeeping, I’ve only seen this fish twice, and the second time I found it I managed to overcome some serious reservations about the asking price and bought it, not knowing when I might get another chance.

Helfrich’s firefish, while rare and expensive, is a stunningly beautiful species that does not present any special difficulties to the experienced aquarium keeper. Despite its price, it deserves to be more popular.

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