Emperor tetra care guide

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

Habitat in the wild

Emperor tetra habitat is Colombia. 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 emperor tetra 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 farms for commercial purposes.

Scientific NameNematobrycon palmeri
Common NamesEmperor tetra
Range and habitatColombia
Size3.0 inches (7.5 cm)
Lifespan3-5 years
Ease of keepingMedium
Minimum tank size40 liters (10 gallons) and more
Temperature75–81 °F (24–27 °C)
Water hardness5-20 dGH


Emperor tetra male max size is 7.5 cm (3 in) and female – 5 cm (2 in). The lifespan in a tank is about 5 years.

The emperor tetra 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 emperor tetra doesn’t have a flash fin. Fish 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 breeders created black emperor tetra called – Nematobrycon palmeri black.

Nematobrycon palmeri black

Difficulties in keeping

Care is easy, since the emperor tetra 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.

Care and keeping in a tank

Tank size

A couple can be kept in a tank about 10 gallons capacity, but again, it’s more preferable to keep a school more than 6 emperor tetras 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.

Tank decor

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 coloring more attractive.

Water parameters

Requirements to tetra care are standard: clean regularly renewed water, peaceful tank mates and diversified feed. Although the emperor tetra is bred a lot and it has adapted to different water parameters, the ideal ones are: water temperature 75–81 °F (24–27 °C), pH: 6.0 – 7.5, 20 dGH.


In the wild 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.

Tank mates

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 emperor tetra is active, peaceful and contrasts in coloring with many brightly colored fishes. Tank mates can be guppies, swordtails, zebra danio, other tetras and peaceful catfish species like Corydoras.

You should avoid large fishes as tank mates – like flowerhorn or green terror which will consider tetras as feed.

Gender differences: male vs female

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 – greenish one.

Male proctal fin has dark edges and female abdomen is more rounded.


At the age of 6 month becomes reproductive. Minimal length of a spawning tank for 1 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 couple when the female isn’t ready for spawning, the male can kill her.

But when there are several female in a spawning tank the emperor tetra male 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 °C, acidity from 6,0 to 6,8.

The eggs grow in more acidic and soft water, but later juveniles may get ill.

The alpha 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 emperor tetra female 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 emperor tetra 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.