Emperor Tetra in Aquarium: Creating a Healthy and Vibrant Habitat

The Emperor Tetra, scientifically known as Nematobrycon palmeri, is a popular freshwater fish species among aquarium enthusiasts. A fish 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. Emperor Tetras are prized for their striking appearance and peaceful nature, making them a popular choice for freshwater aquariums. With proper care and attention to their tank requirements, they can thrive and provide an attractive display in your aquarium.

Habitat in the wild

The emperor tetra belongs to the family Characidae, which is a diverse family of freshwater fish commonly referred to as characins or tetras. The Characidae family is extensive, consisting of numerous species found in South America, Central America, and Africa. Some other well-known tetras that belong to the Characidae family include neon tetras, cardinal tetras, black skirt tetras, and serpae tetras.

In their natural habitat, emperor tetras (Nematobrycon palmeri) are found in the Amazon Basin of South America, specifically in the 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 in densely vegetated areas.

The Amazon Basin is known for its vast rainforest and interconnected river systems. Emperor tetras are typically found in blackwater or clearwater environments, where the water tends to be acidic and soft. These waters are characterized by tannins leached from decaying organic matter, resulting in a dark, tea-colored appearance. The pH in their natural habitat can range from slightly acidic to neutral, typically around 6.0-7.5.

The Emperor tetra’s natural habitat is densely vegetated with submerged plants, floating vegetation, and overhanging vegetation, providing ample hiding places and shade. They prefer areas with low to moderate light intensity. The presence of aquatic plants and vegetation is crucial for their survival, as it offers protection, breeding sites, and a source of food.

In their native range, emperor tetras are part of a complex and diverse ecosystem. They coexist with various other fish species, including other tetras, catfish, characins, and dwarf cichlids. This mix of species contributes to the overall biodiversity of the region and the intricate food web within the Amazon Basin.

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.


Emperor tetras are relatively small fish, typically reaching a size of 2-2.5 inches (5-6 cm) in length. Males tend to be slightly larger than females and may exhibit more vibrant coloration. Their slender and elongated bodies, combined with their flowing fins, contribute to their graceful appearance in an aquarium setting.

The average lifespan of emperor tetras in captivity is typically around 3-5 years. However, with proper care and optimal conditions, some individuals may live slightly longer.

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.

Black emperor tetra

The breeders created black emperor tetra called – Nematobrycon palmeri black. While the Nematobrycon palmeri typically exhibits blue-green, there are variations within the species that can produce darker colors, including black.

There is a selectively bred variation of the emperor tetra known as the “Black Emperor Tetra.” This variety has been developed through selective breeding to intensify the black coloration. Black Emperor Tetras typically have a predominantly black body with the same elongated and slender shape as the standard emperor tetras.

The black coloration in these selectively bred specimens can vary in intensity, with some individuals displaying a deep black hue while others may exhibit a more charcoal or dark gray coloration. These black variations of emperor tetras are popular among aquarium hobbyists for their unique and striking appearance.

Scientific NameNematobrycon palmeri
Common NameEmperor Tetra
OriginAmazon Basin (Colombia)
Size2-2.5 inches (5-6 cm)
Lifespan3-5 years
Water ParametersSoft to moderately hard water, pH 6.0-7.5
Temperature Range75-82°F (24-28°C)
Aquarium Size20 gallons (75 liters) or larger
BehaviorPeaceful, schooling fish
ColorationIridescent blue-green upper body, red or orange lower body
DietOmnivorous, accepts flake or pellet foods; supplement with live or frozen foods
CompatibilityPeaceful community fish, best kept in groups of 6 or more
BreedingEgg-scatterers, remove adults after spawning, eggs hatch in 24-36 hours
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.

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

Care and keeping in a tank

Tank size

For emperor tetras, it is recommended to provide a tank size of at least 20 gallons (75 liters) or larger. This size allows for adequate swimming space and provides a comfortable environment for a small school of emperor tetras. 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.

Emperor tetras are active fish that appreciate open swimming areas as well as areas with vegetation and hiding spots. Providing them with a spacious tank allows them to exhibit their natural behavior and reduces stress within the group.

Tank decor

Include live plants in the aquarium, such as Amazon Sword (Echinodorus species), Java Fern (Microsorum pteropus), Java Moss (Taxiphyllum barbieri), or Anubias (Anubias species). These plants provide cover, create shaded areas, and contribute to the overall aesthetics of the tank. Consider incorporating floating plants like Water Sprite (Ceratopteris species), Duckweed (Lemna minor), or Amazon Frogbit (Limnobium laevigatum). These plants provide additional shade and create a sense of security for the emperor tetras.

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. Emperor tetras are not particularly picky about substrate types, but a natural-colored substrate like sand or fine gravel can enhance the overall aesthetics and provide a more natural appearance.

Adding driftwood or bogwood to the tank helps replicate the natural habitat of Emperor Tetras. It not only provides hiding spots but also releases tannins into the water, mimicking the blackwater or clearwater conditions they are accustomed to.

Water parameters

Requirements to tetra care are standard: clean regularly renewed water, peaceful tank mates and diversified feed. Emperor tetras originate from the Amazon Basin, where the water is typically soft, slightly acidic to neutral, and warm. Although the emperor tetra is bred a lot and it has adapted to different water parameters, the ideal ones are:

  • Temperature: 75-82°F (24-28°C)
  • pH: 6.0-7.5
  • Hardness: Soft to moderately hard water (2-15 dGH)

Ensure adequate filtration to maintain water quality and provide oxygenation. Regular partial water changes (around 20% every 1-2 weeks) help maintain optimal water parameters and remove accumulated waste.


Emperor tetras are omnivorous fish that have a relatively flexible diet. In their natural habitat, they primarily feed on small insects, zooplankton, and plant matter. In the aquarium, they readily accept a variety of foods, including dry flakes, pellets, and live/frozen foods.

High-quality commercial flake or pellet foods formulated for tropical fish are a suitable staple diet for emperor tetras. Look for products that offer a balanced nutritional profile and contain a mix of proteins, vitamins, and minerals. Feed them small portions a few times a day, ensuring they consume the food within a few minutes.

To provide variety and additional nutrients, supplement their diet with live or frozen foods. Suitable options include brine shrimp, daphnia, bloodworms, and mosquito larvae. These foods mimic their natural diet and are usually eagerly accepted. Feed live or frozen foods as a treat 2-3 times a week.

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.

Here are some examples of suitable tank mates for emperor tetras:

Gender differences: male vs female

In emperor tetras, there are some visible differences between males and females, primarily in terms of coloration and size. Here are the general characteristics that can help distinguish male and female:

Male Emperor Tetras:

  1. Size: Males tend to be slightly larger than females, both in overall length and body mass. They may appear more elongated and robust.
  2. Coloration: Male exhibit more intense and vibrant colors compared to females. Their blue-green upper body is usually more vivid, and the red or orange coloration on the lower body is typically brighter.
  3. Fin Length: The dorsal fin of male is usually more elongated and prominent, extending farther back compared to that of females. This elongated dorsal fin gives them a more elegant appearance.

Female Emperor Tetras:

  1. Size: Females are generally slightly smaller and more slender compared to males.
  2. Coloration: The colors of female are typically less intense than those of males. They may have a slightly muted or less vibrant blue-green color on their upper body, and the red or orange on the lower body may be less pronounced.
  3. Fin Length: The dorsal fin of female is usually shorter and less extended compared to that of males.

It’s important to note that these differences in size and coloration can vary between individuals, and they may not be as pronounced in younger or less mature specimens. Additionally, the differences may become more noticeable during the breeding season when males may display even more intense colors and engage in courtship behaviors.


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.