i cant think
Wrasse Addict
Excellence Award
Reef Tank 365
Article Contributor
UK Reef Club Member
Rock Pool Reef Keepers
My Tank Thread
My Aquarium Showcase
Well, I never thought that I’d write this but I found it rather interesting and I’m sure many others will.
So, you’re likely sitting on a fish that you think is Nemateleotris helfrichi but… It’s not!
Here’s the break down on this genus of Dartfish.
First off what is the genus Nemateleotris for those who don’t go into the scientifics?
Nemateleotris is a genus from the family Gobiidae which is the ‘True’ Goby Family. Now, Nemateleotris was originally split off into 5 species;
Nemateleotris magnifica (The first described of this genus in 1938)
Nemateleotris helfrichi (This species was described in 1973)
Nemateleotris decora (This species was also described in 1973)
Nemateleotris exquisita (This species later came into the genus in 2013)
However recently there was a 6th described species from this genus, Nemateleotris lavandula.
I know I’ve just done a huge information dump but not really explained any differences. So, I guess your question is how do you identify the Lavandula from a Helfrichi or maybe an Exquisita from a Decora?
Well, I’ll happily help there starting with the two older species - Exquisita and Decora.
The Exquisite Firefish is believed to be identified through having a lighter and more yellow anterior whereas the Decora is thought to have a darker, more grey anterior. More minimal ways include the diameter of the eye and length of the first dorsal fin. However it is questioned if these two are actually different species altogether or just simply a variation from different regions.
Nemateleotris exquisita - Exquisite Firefish
Nemateleotris decora - Purple Firefish
Now, let’s go into the fun bit… Helfrichi vs Lavandula.
The Lavender-Blushed Firefish is what we used to believe was the ‘Normal’ Helfrichi and the deep water Cook Island Helfrichi Firefish was believed to be just a variant of N. helfrichi. The biggest colour difference between the two is on the head, the Lavender Firefish has the beautiful yellow head and is the most common species we see in captivity. The true Helfrichi Firefish however has a very different head colour and is almost completely purple! A minor difference is with the mouth, the true Helfrichi has a black band on the upper jaw however the Lavandula lacks that band. The other difference is that the true Helfrichi Firefish has a much more restricted region of origin in the Pacific Ocean between the Cook Islands and French Polynesia. Whilst the Lavander Firefish is found all throughout the Indo-Pacific from the north east of Australia right up to Japan.
Nemateleotris helfrichi - Helfrichi Firefish
Nemateleotris lavandula - Lavander-Blush Firefish
I hope you enjoyed this ‘deep dive’ into this deep water genus of Gobies! And yes, Gobies, Firefish and Dartfish are the same they all go under the same family but are spread out through many genera.
P.S. Any photos used were from quick google searches, none are mine.
So, you’re likely sitting on a fish that you think is Nemateleotris helfrichi but… It’s not!
Here’s the break down on this genus of Dartfish.
First off what is the genus Nemateleotris for those who don’t go into the scientifics?
Nemateleotris is a genus from the family Gobiidae which is the ‘True’ Goby Family. Now, Nemateleotris was originally split off into 5 species;
Nemateleotris magnifica (The first described of this genus in 1938)
Nemateleotris helfrichi (This species was described in 1973)
Nemateleotris decora (This species was also described in 1973)
Nemateleotris exquisita (This species later came into the genus in 2013)
However recently there was a 6th described species from this genus, Nemateleotris lavandula.
I know I’ve just done a huge information dump but not really explained any differences. So, I guess your question is how do you identify the Lavandula from a Helfrichi or maybe an Exquisita from a Decora?
Well, I’ll happily help there starting with the two older species - Exquisita and Decora.
The Exquisite Firefish is believed to be identified through having a lighter and more yellow anterior whereas the Decora is thought to have a darker, more grey anterior. More minimal ways include the diameter of the eye and length of the first dorsal fin. However it is questioned if these two are actually different species altogether or just simply a variation from different regions.
Nemateleotris exquisita - Exquisite Firefish
Nemateleotris decora - Purple Firefish
Now, let’s go into the fun bit… Helfrichi vs Lavandula.
The Lavender-Blushed Firefish is what we used to believe was the ‘Normal’ Helfrichi and the deep water Cook Island Helfrichi Firefish was believed to be just a variant of N. helfrichi. The biggest colour difference between the two is on the head, the Lavender Firefish has the beautiful yellow head and is the most common species we see in captivity. The true Helfrichi Firefish however has a very different head colour and is almost completely purple! A minor difference is with the mouth, the true Helfrichi has a black band on the upper jaw however the Lavandula lacks that band. The other difference is that the true Helfrichi Firefish has a much more restricted region of origin in the Pacific Ocean between the Cook Islands and French Polynesia. Whilst the Lavander Firefish is found all throughout the Indo-Pacific from the north east of Australia right up to Japan.
Nemateleotris helfrichi - Helfrichi Firefish
Nemateleotris lavandula - Lavander-Blush Firefish
I hope you enjoyed this ‘deep dive’ into this deep water genus of Gobies! And yes, Gobies, Firefish and Dartfish are the same they all go under the same family but are spread out through many genera.
P.S. Any photos used were from quick google searches, none are mine.
