Marijke Puts introduces all the species that belong to the wonderful genus of Nemateleotris.
For most of these creature features, I have to scour large genera and pick just a few species to highlight. There’s just never enough space to discuss them all, and it feels like being made to choose a favourite child.
However, its a different story for the firefish of the genus Nemateleotris. Depending on who you ask, there are only four or five firefish species in all, so we can give each the attention it deserves.
Their care requirements are all fairly similar, but their availability and price differ widely.
The Firefish
When aquarists talk about firefish, they’re usually referring to one species in particular: N. magnifica, known simply as the firefish (among a bunch of other names).
This is likely due to the fact that it’s simply the easiest to catch – aquaculture companies haven’t cracked captive firefish breeding yet, meaning that all stock comes from the wild. That’s easy enough for this species, which boasts a very wide natural range and is usually found on shallow reefs. Its cousins, which prefer deeper waters, are more of a challenge.
In any case, I’m not complaining. The firefish, its dorsal fin proudly high and sporting a lovely colour gradient from a yellow face to silver to bright orange, represents this beautiful genus perfectly. Your ideal starter firefish thanks to its low price, hardy nature, and easy sourcing.
Photo by Shutterstock
Firefish Fact File
Scientific name: Nemateleotris magnifica
Size: Up to 9cm (3.5”).
Origin: Indo-Pacific.
Habitat: Shallow reefs and the upper sections of the outer reef slopes.
Tank Size: 60x35x35cm (24x14x14”).
Temperament: Peaceful to anything not closely resembling themselves, and they are reef safe. Do not keep them with anything too territorial and boisterous, as it may cause them to hide.
Feeding: Thrives on small regular feeds throughout the day, offer a mix of frozen, live and prepared foods.
Availability & cost: Easy to find, from £25.
Purple Firefish
Purple isn’t a very common colour in fish, but it appears firefish never got the memo. Purple firefish, also called elegant firefish, have quite conservatively coloured bodies, fading from light grey to a darker brownish grey hue, but the head and fins are a veritable party of yellows, reds, pinks, and luxurious violets. A very attractive fish, but without the huge price tag of its rarer cousins.
Note that you’ll sometimes see almost identical specimens offered for sale labelled as N. exquisita, the exquisite firefish. This is the mythical ‘fifth firefish’ I was talking about earlier. It was christened in 2013 and supposed to occur only in the Indian Ocean and Red Sea, but most ichthyologists feel it doesn’t deserve full species status. I’m inclined to agree – for all the squinting in the world, I can’t tell it apart from N. decora.
Photo by Shutterstock
Purple Firefish Fact File
Scientific name: Nemateleotris decora
Size: Up to 8.5cm (3.3”)
Origin: Indo-West Pacific
Habitat: Reef areas with sand/rubble and outer drop-offs, with strong currents and at depths greater than 25m (82’).
Tank Size: 60x35x35cm (24x14x14”)
Temperament: Peaceful – although the most argumentative of the firefish – and reef safe. Do not keep them with anything too territorial and boisterous, as it may cause them to hide.
Feeding: Thrives on small regular feeds throughout the day, offer a mix of frozen, live and prepared foods.
Availability & cost: Easy to find, £40-50
Helfrich’s Firefish
I like to think of Helfrich’s firefish as a sort of inverted purple firefish: instead of the fins being the colourful part, it’s the lovely lilac body. The head shows the faintest hint of yellow with a black stripe on the lips, while the fins are a neutral, almost transparent yellowish-green.
This is not an easy firefish to source, probably because it often favours reefs up to 100m (328’) deep – which is way beyond normal scuba diving depth! And to make matters worse, as we’ll see below, many of the Helfrichi's firefish offered for sale are actually a similar-looking doppelgänger.
Still, some aquarists think the very steep price, potential confusion, and often rather long wait are worth it – if not for the species’ spectacular appearance, then certainly for the bragging rights.
Photo by Quality Marine
Helfrichi’s Firefish Fact File
Scientific name: Nemateleotris helfrichi
Size: Up to 6cm (2.4”).
Origin: Eastern and Central Pacific from French Polynesia and the Cook Islands.
Habitat: Sandy and rubble-filled reef areas usually at depths of at least 40m (130’)
Tank Size: 60x30x30cm (24x12x12”)
Temperament: Peaceful and reef safe. Do not keep them with anything too territorial as it may cause them to hide and be outcompeted at feeding time.
Feeding: Thrives on small regular feeds throughout the day, offer a mix of frozen, live and prepared foods.
Availability & cost: Hard to find, £150-200
Lavender-Blushed Firefish
The new kid on the block! The tiny lavender-blushed dartfish was described in 2023. Previously thought to be a regional variant of Helfrich’s firefish, it was raised to full species status based on both molecular analysis and subtle differences in appearance. And what a stunner it is!
If you’d like to buy a lavender-blushed dartfish, searches for N. lavandula will usually come up short. That doesn’t mean it’s not available at all.
Dealers haven’t quite caught on to the split from N. helfrichi yet, still offering it under that name in most cases. With some practice, you can tell the difference yourself – and in our experiences, N. lavandula is actually the more common of the two in UK stores.
If it has a pink head and a little black moustache, it’s a Helfrich’s; if its head is yellow and moustache-free, it’s a lavender. Happy hunting (and don’t forget your wallet).
Photo by Shutterstock
Lavender-Blushed Firefish Fact File
Scientific name: Nemateleotris lavandula
Size: Up to 5.2cm (2”).
Origin: Western and Central Pacific from Japan down to Northeastern Australia.
Habitat: Sandy and rubble-filled reef areas usually at depths of at least 40m (130’).
Tank Size: 60x30x30cm (24x12x12”).
Temperament: Peaceful and reef safe. Do not keep them with anything too territorial as it may cause them to hide and be outcompeted at feeding time.
Feeding: Thrives on small regular feeds throughout the day, offer a mix of frozen, live and prepared foods.
Availability & cost: Hard to find, often mislabelled as N. helfrichi and prices are therefore the same.
Time to choose your species
Few reef species are as widely beloved in the hobby as firefish. Even the carnivore enthusiasts and invertebrate lovers have a soft spot for this little goby, and for good reason: thanks to its small size, even temper, and sturdy nature, it might just be the perfect species for the peaceful reef.
It is almost time to decide which one to stock in your reef tank, but check out our guide to keeping firefish first to ensure your tank is suitable!
Want to keep one of these species but not sure where to start when creating your first marine tank? Well, check out our beginner's guide to reef tanks!