There are many fish species that aquarists once coveted that could be found only in the pages of fish books. Many of these species were inhabitants of deep-reef habitats or were found in locations where limited fish collecting occurred. This was the case with the Helfrich’s firefish (Nemateleotris helfrichi), an extraordinary relative of the ubiquitous firefish N. splendens. While it once was almost nonexistent in the aquarium trade, N. helfrichi is now readily available to marine aquarists at reasonable prices.
Difficulty: The Helfrich’s firefish is a vigorous aquarium charge. It will readily acclimate, is not parasite-prone and will do well in a variety of aquarium venues. The Helfrich’s firefish will eat meaty foods, such as frozen Cyclops, frozen fish eggs, preparations for marine carnivores and even flake food. Care should be taken to provide the Helfrich’s firefish with a varied diet so that it does not fade in color.
Physical description: The Helfrich’s firefish is purplish on the front of its body, fading to a light violet on the rear of the body. The head is yellow, as are the dorsal, anal and caudal fins. The high dorsal spine is blue with a red-rear margin. There are two color forms, with individuals from French Polynesia exhibiting a different color pattern than those from Micronesia and Japan (the color form previously described). The Polynesian fish are less common in the aquarium trade and are typically two or three times more expensive. Nemateleotris helfrichi reaches about 2.5 inches in length.
Range: Helfrich’s firefish is known from Japan, Micronesia and Polynesia (excluding the Hawaiian and Pitcairn islands). The Helfrich’s firefish is a resident of deep reef rubble slopes, having been reported from 100 to 225 feet (it is rarely seen in water less than 120 feet). The Helfrich’s firefish hovers in the water column and feeds on zooplankton pushed past by ocean currents. When threatened, N. helfrichi will dive headfirst into a burrow in the sand.
Compatibility: Nemateleotris helfrichi, like all the firefish, is not likely to bother any other fish or invertebrates that it shares an aquarium with it. However, keeping them together can be tricky. Nemateleotris helfrichi is thought to be one of the more social species when it comes to living with members of its own kind. With the Helfrich’s firefish it is possible to keep a small group together in your aquarium. Make sure that the Helfrich’s firefish has good places to hide out; if one individual does start picking on the others, remove it.
Beware that the other two firefish are not usually as tolerant of conspecifics and may also pick on N. helfrichi in smaller aquariums (less than 100 gallons). Because of its small size and placid nature N. helfrichi is a sitting duck for more combative species and predator fish. The Helfrich’s firefish has been attacked by dottybacks, damsels (including larger anemonefish) pygmy angelfish, hawkfish, sand perches and wrasses. I have even had Helfrich’s firefish chased by larger shrimpgobies. While Helfrich’s firefish is no threat to inverts, N. helfrichi has been known to fall prey to carpet anemones (especially at night) and crabs.
Aquarium conditions: The Helfrich’s firefish is a perfect addition to the nano-reef aquarium. A pair or group can also make for striking subjects in larger reef aquariums. Acceptable water parameters for the Helfrich’s firefish are a pH of 8.1 to 8.4, specific gravity of 1.019 to 1.025 and a water temperature of 74 to 82 degrees Fahrenheit.
Care considerations: All of the firefish are proficient jumpers that seem to be able to find the smallest hole in the aquarium top. Make sure any aquarium housing the Helfrich’s firefish is adequately covered. The Helfrich’s firefish is more likely to jump when startled by a sudden change in light level or if it is being picked on.
The Helfrich’s firefish sometimes suffers from swim bladder disorders as a result of being improperly decompressed when brought to the surface during collection. Individual Helfrich’s firefish that have difficulty staying stationary in the water column or constantly swim with their heads directed toward the aquarium bottom may have a damaged swim bladder. Unfortunately, fish with such problems quickly succumb in aquaria. In fact, if you notice telltale signs of swim bladder disorders, avoid purchasing such fish altogether.
Breeding: The Helfrich’s firefish may spawn in home aquaria. Courtship in N. helfrichi consists of the male positioning himself in front of the female and quivering. Male Helfrich’s firefish become more aggressive toward tankmates at this time and their color intensifies. A female Helfrich’s firefish will rest in a depression in the gravel, while the male Helfrich’s firefish moves alongside her and deposits his gametes on the substrate.