Information, Characiformes (Characins), Freshwater fish, Species, Tetras

Emperor tetra (Nematobrycon palmeri)

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by Jason Matthews



The Emperor Tetra, with its scientific name Nematobrycon palmeri, is a stunning and visually appealing fish species guaranteed to add a pop of color to any aquarium. It is indigenous to South America’s freshwater streams and tributaries and has gained popularity among fish lovers due to its peaceful demeanor and striking hues. Whether you’re new to fish keeping or have prior experience, the Emperor Tetra is an excellent option for introducing color and character to your aquarium. 

This article will take a deep dive into the world of Emperor Tetras, covering everything from their origin and physical characteristics to their behavior, tank setup, and diet. Therefore, keep reading if you’re eager to discover more about this intriguing species!


Scientific Name: Nematobrycon Palmeri
Common Names: Emperor tetra
Life Expectancy: 5-8 years
Adult Size: 5 cm (2 inches)


HabitatAmazon Basin
OriginSouth America
Care LevelEasy
Tank LevelMiddle
Minimum Tank Size30 gallons
Water pH6.0-7.5
Water Temperature22-28°C (72-82°F)
Water Hardness4-12°dGH
Tank MatesPeaceful community fish

Fun Fact Corner

The Emperor Tetras have been known to exhibit a peculiar activity called “shoaling”. This behavior is characterized by a group of Emperor Tetras swimming together in a tight formation, almost as if they are choreographed. This behavior is considered a form of protection, as the fish feel safer swimming in a group than alone. This can be a fascinating thing to observe in your tank, and it is also interesting to note that Emperor Tetra’s shoals are usually made up of fish of the same sex.


The Emperor Tetra originates from the freshwater streams and tributaries of South America. More precisely, it is commonly found in Colombia and Ecuador, where it inhabits the swift, crystal-clear waters of the Andean foothills. In the wild, Emperor Tetras inhabit areas with high oxygen levels, moderate to high water flow, and a pH range of 6.0-7.5. They are commonly found in clear, fast-moving waters shaded by overhanging vegetation.

The Emperor Tetra was first described by Géry in 1977, but it has been collected for the aquarium trade since the early 1900s. Over the years, it has become increasingly popular among fish enthusiasts due to its striking colors and peaceful nature. Today, it is widely available in pet stores and online retailers and is a popular choice for both beginner and experienced fish keepers.


The Emperor Tetra is a beautiful fish well-known for its stunning appearance. Its iridescent blue body and bright red fins create an eye-catching contrast, making it a popular choice among fish enthusiasts. Males typically have more pronounced red coloration than females and have an elongated, slender body with a slightly flattened belly. Additionally, males are generally smaller and slimmer than females.

One of the Emperor Tetra’s unique features is a black spot at the base of its dorsal fin, which sets it apart from other tetra species. These fish are peaceful and active swimmers, making them an excellent addition to any community aquarium. They are also well-suited to smaller tanks due to their relatively small size. Emperor Tetras are often found swimming in large schools in their natural habitat, and keeping them in groups of at least six individuals in captivity is recommended.

Both novice and seasoned fish keepers will find them an excellent choice because of their vivid colors, which offer a lovely personality to any aquarium.

Both novice and seasoned fish keepers will find them an excellent choice because of their vivid colors, which offer a lovely personality to any aquarium. Emperor Tetras are also known for being relatively easy to care for and maintain, making them a great option for those looking to add a pop of color to their aquarium without too much extra effort.


The Emperor Tetra is a relatively small fish species, reaching an adult size of approximately 2-2.5 inches. They are known for their compact size and are well suited for smaller aquariums and community tanks, with a recommended minimum tank size of 20 gallons. They can be kept in groups of 6 individuals or more, and their small size allows them to easily move and swim in the tank without taking up too much space.

However, it is important to note that Emperor Tetras are still considered a small fish species and may not be suitable for aquariums home to larger or more aggressive fish species. They are best kept with other small to medium-sized fish with similar water and temperature requirements.

During their growth, providing them with a balanced and nutritious diet is essential to ensure they reach their full potential.


Determining the gender of an Emperor Tetra can be challenging, but some subtle differences can help. Males typically have more pronounced red coloration on their fins, especially on the dorsal, tail, and anal fins. They also have a longer, more pointed dorsal fin and a slimmer body shape and are usually slightly larger than females. On the other hand, females tend to have a more muted red coloration on their fins and a rounder body shape. They are usually slightly smaller in size than males.

It’s important to note that these gender differences may vary depending on the fish’s health and diet, so it’s not always possible to determine their gender by appearance alone. A more accurate way to determine the gender of an Emperor Tetra is to observe their behavior and examine their vent area, where the ovipositor of females can be seen.


The Emperor Tetra is renowned for its friendly and engaged behavior. They are schooling fish and should be kept in groups of six or more individuals, which allows them to feel safe and secure in their environment. They are active swimmers and can often be seen swimming near the water’s surface in search of food.

The Emperor Tetra is recognized for its playful behavior and is commonly seen engaging with other fish in its tank. It is not known to exhibit aggressive behavior towards other fish species and can be kept with a variety of tank mates with similar water and temperature requirements.

It is significant to remember that Emperor Tetras are sensitive to changes in their surroundings and can experience stress if circumstances are not ideal. They need a well-kept aquarium with clean water, the proper temperature range, and a healthy diet. They can live up to four years if kept in the best possible conditions.


When selecting compatible tankmates for Emperor Tetras, it’s crucial to take into account their gentle and delicate disposition. These fish are ideally housed in a community tank with other small to medium-sized peaceful fish.

Here is a list of good tankmates for Emperor Tetras:

It is important to avoid keeping Emperor Tetras with larger, more aggressive fish as they may bully or harm the smaller tetras. Furthermore, it’s essential to refrain from keeping them with fish that demand contrasting water conditions.

Tank conditions

Regarding tank conditions for Emperor Tetra, it is vital to provide a clean and well-maintained environment. These fish are sensitive to changes in water chemistry and temperature and require a stable environment to thrive. The ideal water temperature for Emperor Tetras is between 74-82°F (23-28°C). Water should be slightly acidic to neutral, with a pH range of 6.0-7.5. The fish are also sensitive to water hardness; the ideal range is between 4-10 dH.

Aquariums should be well-filtered, and the water should be changed at least once a week. The recommended tank size is at least 20 gallons (75 liters) for a school of six or more. Emperor Tetras should be kept in a well-planted tank with plenty of hiding spots and areas of open swimming space.

It’s important to note that these fish are sensitive to changes in their environment, so it’s crucial to test the water regularly and maintain the proper water conditions to ensure the health and well-being of the fish.


Emperor Tetras are not fussy eaters and take a wide variety of foods when fed. They consume small crustaceans, insects, and worms in the wild. In captivity, they will readily accept a variety of commercial fish foods such as flakes, pellets, and frozen foods. It is important to provide a balanced diet that includes a variety of foods to ensure that the fish receive all the necessary nutrients.

A good diet for Emperor Tetras should include:

  • High-quality flakes or pellets as a staple diet
  • Frozen or live foods such as bloodworms, brine shrimp, and daphnia as a supplement
  • Vegetable-based foods such as blanched spinach, lettuce, or peas

It’s important to remember to feed them small portions multiple times a day rather than one large portion. Overfeeding can cause water quality issues, so be sure to remove any uneaten food.


Breeding Emperor Tetras can be a rewarding experience for fish enthusiasts, but it does require some preparation and knowledge. These fish are egg-layers and will lay their eggs on a flat surface, such as a leaf or a piece of wood.

To prepare for breeding, it is important to have a separate tank or breeding box specifically for this purpose. The tank should be dimly lit and have a fine-leaved plant or spawning mop for the fish to lay their eggs on. The water temperature should be slightly warmer than the tank conditions for the adults, around 80-82°F. 

Having a group of at least 6-8 healthy adults is also important, with a ratio of 1 male to 2-3 females. When ready to breed, the males display their best colors and engage in courtship behavior to attract the females. Once the female has laid her eggs, the parents should be removed from the breeding tank to prevent them from eating them.

The eggs will hatch in about 24-36 hours, and the fry will be free-swimming within 3-4 days. The fry will require infusoria or finely crushed flakes for the first few days, then they can be fed with baby brine shrimp or micro worms.

It’s worth noting that breeding Emperor Tetras is not an easy task; it may require some patience and dedication. But with the right conditions and setup, it can be a very rewarding experience.


Understanding diseases that may harm your Emperor Tetra is crucial for maintaining their health.

Common illnesses that can affect Emperor Tetras includes:

  • parasitic infections, 
  • fungal infections
  • bacterial infections. 

Maintaining proper water quality and cleanliness in the tank is crucial to prevent the spread of disease. Additionally, observing your fish for any signs of illness, such as lethargy, loss of appetite, or abnormal behavior, is crucial. If you suspect your fish may be ill, it is best to consult with a veterinarian experienced in treating fish or a knowledgeable fish expert for proper diagnosis and treatment.

It is also important to purchase your Emperor Tetra from a reputable source and to quarantine new fish before introducing them to a community tank. With proper care and attention, your Emperor Tetra can thrive and live a long, healthy life.


Jason Matthews

My name is Jason Matthews, and welcome to my website. When other kids were bragging about how their dog could sit and roll over, I was bragging about my latest Betta Fish and the cool sea castle I just added to his aquarium. 

Jason aquariume

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