A conversation at last week’s meeting, which itself was sparked by a question in the quiz the week before has brought me back to the subject of scientific names.
The question was – what colour of eyes has the emperor tetra? The answer is – depends what you mean by emperor tetra. There are three or four species of fish known in the hobby as emperor tetra and this is where the confusion lies.
The fish perhaps most often seen for sale under this name is:
Inpaichthys kerri Géry & Junk, 1977
This is a small tetra from Mato Grosso, Brazil. It’s a very attractive blue and indeed is commonly traded as blue-emperor tetra. It’s also sometimes sold as the royal or king tetra. In this species the males have a blue adipose fin with the females fin being brown. As far as I can tell both sexes have a metallic greenish-blue eye.
Another fish commonly sold as emperor tetra is:
Nematobrycon palmeri Eigenmann, 1911
A handsome blue and purple fish from Colombia this species makes a splendid addition to a community tank of small peace-loving fishes and is also a great subject for a breeding project. This species has no adipose fin and males have metallic-blue eyes whilst female eyes are metallic greenish-yellow.
The last species that is also known as emperor tetra is:
Nematobrycon lacortei Weitzman & Fink, 1971
This is possibly the most beautiful of the emperor tetras and it’s also the least commonly sold. It has several “common” names including rainbow emperor tetra, red-eyed emperor tetra and La Corte’s emperor tetra. Named after US fish-breeder Rosario LaCorte this species is also from Colombia. As one of this species’ common names suggests the males have bright red eyes, the females have bluish-green eyes. Like N. palmeri it lacks an adipose fin.
There is another name that crops up now and again and that is Nematobrycon amphiloxus. However this is a synonym of N. palmeri and is sometimes given to dark specimens. The eye colour is the same as for N. palmeri.
All told this is a beautiful group of fish and well worth the trouble of getting to know them better.
Information on breeding the emperor tetra
Seriously fish – Nematobrycon lacortei – Rainbow Tetra
Seriously fish – Nematobrycon palmeri – Emperor Tetra
Seriously fish – Inpaichthys kerri – Purple Emperor Tetra