Emperor tetra (Nematobrycon palmeri)

A tank fish called emperor tetra (Nematobrycon palmeri) feels itself rather comfortable in community tanks and thickly planted ones desirably.

Emperor tetra breeding can even occur there, especially if the fish are kept in a small school. It’s good if there are more than 6 fish in a school, since otherwise they may nip other fishes fins.

Therefore keeping tetras in a school significantly smooths such a behavior and switches them to dealing with species of their kind.


emperor tetra fish

Inhabitance in the wild

Habitat is Columbia. The fish is endemic (the kind that inhabits only in this specific area) of the river San Juan and Atrato.

Emperor tetra can be encountered in waters with slow water flow, in small tributaries and streams joining rivers.

The fish isn’t very widely spread in the wild, but you can quite often see it in the amateurs tanks, since all fishes you can see on sale are bred in the fish farms for commercial purposes.


The fish has elongated body a bit flattened from sides, the line of its back is very curved. Blue fluke is a unique one, it has three-bladed shape which is formed by the fluke long central rays.

The fish doesn’t have a flash fin. Emperor tetra is colored in dark blue on the sides below the line. The proctal fin has a black line and yellow edges.

The tail outer rays, the string and the first ray on the dorsal are black colored. Has a very expressive color of the eyes – it’s emerald-blue.

The fish breeders created black emperor tetra called- Nematobrycon palmeri black.

Difficulties in keeping

Care is easy, since the fish isn’t demanding. It can be kept in a community tank, but it’s important to remember that it’s a schooling fish, so keep the school more than 6 species.

Keeping in a tank

A couple of fish can be kept in a tank about 10 gallons capacity, but again, it’s more preferable to keep a school more than 6 fish in a tank not less than 20-40 gallons and the females should prevail.

The tank must be closed, because the fish can jump out.

Scientific NameNematobrycon palmeri
Common NameEmperor tetra
Tank size20-40 gallons (80L and more)
Temperature75–81 °F (24–27 °C)
Length3.0 inches (7.5 cm)

Prefers tanks with a lot of plants and soft lighting, because it lives in rivers of Columbia with the same conditions.

Besides, dark bottom substrate of a tank and green plants make the fish coloring more attractive. Requirements to emperor tetra care are standard: clean regularly renewed water, peaceful tank mates and diversified feed.

Although the fish is bred a lot and it has adapted to different water parameters, the ideal ones are: water temperature 24-27С, pH: 5.0 – 7.5, 25 dGH.


Emperor tetra is a territory dependent fish, so in the school there is only one alpha male, – who has taken the largest territory. When guarding the territory male swims and leans a bit forward, at that its tail rises 45 degrees up and looks like a crown.

The fish is active, peaceful and contrasts in coloring with many brightly colored fishes. Tank mates can be different live-bearing fishes, Danio, Rasboras, other tetras and peaceful catfish species like Corydoras.

You should avoid large fishes as tank mates – fishes like American cichlids which will consider tetras as feed.

Sex differences

Males are brighter colored and their dorsals are longer and sharper, then the ones of the female. Female has shorter fins and its iris isn’t that bright. Males have blue colored iris and female fish – greenish one. Male fish proctal fin has dark edges and female abdomen is more rounded. Male max size is 6 cm and female – 5 cm. The fish lifespan in a tank is about 5 years.


In the wild emperor tetra feeds on different insects, worms and larva. In a tank the fish isn’t demanding and it eats both dry and frozen feed, any artificial feed will also do.

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At the age of 6 month emperor tetra becomes reproductive. Minimal length of a spawning tank for 1 fish male and 2-3 females is 60 cm.

However, sometimes spawning occurs in a species tank. As some aquarists think, that putting in a spawning tank a fishes couple when the female fish isn’t ready for spawning, the male can kill her. But when there are several female fish in a spawning tank the male fish attention will be distracted.

There should be some Javan moss, Myriophyllum or Elodea canadensis and some fluctuants on the water surface in the spawning tank. Water parameters are the following: general hardness 1-5°, temperature 24-28°С, acidity from 6,0 to 6,8. The eggs grow in more acidic and soft water, but later juveniles may get ill.

The alpha fish male is kept apart from a female for several weeks before spawning. Fishes put into a spawning tank in the evening start spawning in the morning.

The female fish lays from 50 to 150 large transparent eggs. When the spawning is finished the fish “parents” are removed back into community tank and the water layer in the spawning tank is decreased up to 5-8 cm. You can shade the spawning tank as well.

In 1-2 days juveniles appear and start to swim 4-6 days later. Start feed for the juveniles is only ratifier infusorian at the beginning, on the second day – brine shrimp nauplii that has just hatched.