Care
A much sought-after fish for the home aquarium, Helfrich's Firefish is known from relatively deep waters (>40m) and is typically found over small patches of rubble, sand, or the hard rocky substrates at the bottoms of steep seaward reefs. These fish tend to live in pairs and they are often seen hovering together in the water column feeding on zooplankton; however they tend not to stray far from cover.
This species is an ideal candidate for the mature reef aquarium; it is colourful, relatively peaceful, and readily acclimatises to aquarium life. The tank should be aquascaped with plenty of live rock so that there are numerous nooks and crannies for your firefish to dart into if startled; they especially favour piles of loose rubble. There should be areas of brisk water movement and a high level of oxygenation, these fish can often be seen hovering in the water column, facing the strong current whilst waiting for microscopic food morsels to drift past. Helfrich"s Firefish will rarely become aggressive towards other fish species (except close relatives), but it can be very territorial with its own kind, and they will fight fiercely unless they are a mated pair. For this reason it is best to either keep a single specimen (particularly in smaller, "˜nano" aquaria) or acquire a known mated pair. These fish cannot be easily sexed externally and simply putting two specimens together and hoping for the best is unlikely to work, although adding a group to a large aquarium will usually result in harmonious pairing, with 'spare' fish being removed if they become victims of aggression. Tankmates should be of a peaceful nature in order that the firefish do not feel intimidated at feeding times. Observe very carefully, as firefish are easily bullied. Do ensure that the tank has tightly fitting coverslides and absolutely no escape holes, as these fish are expert jumpers. Take care when acclimatising too, as they will jump from the shipping bag if it is not covered. There are two colour forms of N. helfrichi, with individuals from French Polynesia exhibiting a slightly different colour pattern than those from Micronesia and Japan.
* It seems that the fish we've been familiar with as N. helfrichi is an imposter! The yellow-faced fish that we see regularly turns out to be the Lavender-blushed dartfish newly described as Nemateleotris lavandula.
Feeding
Offer a variety of small meaty foods such as Mysis shrimp, vitamin-enriched brineshrimp, plankton, finely shaved krill/mussel/cockle/clam etc. Feed small amounts several times per day. A fishless refugium for producing an ongoing supply of plankton would be extremely beneficial in keeping these fish well-nourished.
Breeding
This species has not been successfully raised in captivity, although a handful of aquarists claim to have seen eggs. In the wild, firefish are monogamous and deposit their eggs in burrows. These are then thought to be guarded by the parents until hatching; the larvae are pelagic.
