Emperor Tetra Fish 101 (2024 Care Guide)

Featured Image - emperor tetra
Featured Image – emperor tetra
Dr. Mollie Newton
Published by Dr. Mollie Newton PHD| Senior Editor
Last updated: July 10, 2024
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The emperor tetra (Nematobrycon palmeri), despite its remarkable beauty, is often overlooked and less frequently acknowledged in the tetra family. This species does not enjoy the same popularity as other prominent tetra relatives, such as the neon tetra and cardinal tetra.

The emperor tetra’s shimmery blue-gray coloration, hardiness, and peaceful nature make them a fantastic addition to a single-species tank or community tank setup. However, the emperor tetra needs specific care to truly thrive. As an aquarist who’s owned the species for over a decade, I’ll be diving into everything you need to know about these fish in this emperor tetra care guide.

Article Summary

  • Emperor Tetras are a beautiful and peaceful species of tetra fish native to the Atrato river basins and San Juan river basins of Columbia in South America.
  • They require a tank size of at least 10 gallons, with 1 fish for every 2 gallons of water.
  • Emperor Tetras have a varied diet that includes high-quality pellets, live or frozen foods like brine shrimp and worms, and even occasional vegetables.

Species Overview

Emperor Tetra
Emperor Tetra

The emperor tetra (Nematobrycon palmeri) is a species of characid fish that is native to the Atrato river basins and San Juan river basins of Columbia in South America. The emperor tetra’s natural habitat includes slow-moving freshwater bodies of water like streams and tributaries.

While less popular than other tetra species like the neon tetra, cardinal tetra, lemon tetra, and silvertip tetra, these peaceful tetras are a fan-favorite in the aquarium hobby due to their regal appearance.

These freshwater fish display a purple iridescent sheen to their blue-gray coloration, making them a showstopper in species-only and community tanks.

Scientific nameNematobrycon palmeri
Common namesEmperor tetra, blue emperor tetra, royal emperor, imperial blue rainbow tetra, rainbow tetra
DistributionColumbia, South America
Size2 inches
ColorBlue-gray with purple tones
Minimum tank size10 gallons
Place in tankMiddle level


The emperor tetra is a stunning little fish that boasts bright blue gray scales with a purple iridescent sheen in low-light conditions.

What Does the Emperor Tetra Look Like?

Like most tetra species, the emperor tetra has an elongated and slender body with a tapered tail fin. Their fins are translucent with a yellow coloration and black border. The body color of this fish species is blue-gray with a purple iridescent shimmer and a black stripe that runs along the middle.

Special Features

The emperor tetra is easily distinguished by its gorgeous blue-gray scales that have a shimmery purple sheen in subdued lighting. They also have a thick black stripe that extends across the entire length of their body.

A black variation of this fish is also available, which boasts a black body and cream-colored snout.

This fish species is sexually dysmorphic, so the appearance for each sex is slightly different, making them easy to sex. Males are larger and more pointed in body shape. They also have longer dorsal and caudal fins.

Females, on the other hand, are rounder and less vibrant. They also tend to have green eyes, whereas males have blue eyes.

How Big Does the Emperor Tetra Get?

Emperor tetras only grow to approximately 2 inches in length, though some specimens can reach up to 3 inches in size. Males tend to be larger than females.

How Big Is a Black Emperor Tetra?

The black emperor tetra reaches the same size as the classic emperor tetra, which is around 2 inches in length.

Tank Requirements

Woman Placing Empty Aquarium On The Table
Woman Placing Empty Aquarium On The Table

Like all fish, the emperor tetra needs specific tank requirements like a good size tank, peaceful tank mates, and a gentle current to thrive in captivity. In this section of the article, I’ll be going over the ideal setup for this freshwater fish.

Tank Size

As emperor tetras are relatively small fish, they don’t need an overly large aquarium size. A 10-gallon fish tank is a decent volume for a small group of this fish species.

However, bigger is always better, especially if you want to keep more than 6 of these fish or house them in a community tank. If you have the budget for a larger tank,  I’d suggest at least a 30-gallon if you plan on keeping emperor tetras in a community setup.

Personally, I have a group of 10 emperor tetras in a 40-gallon aquarium with a clown pleco, dwarf gourami, and some aquatic snails.

How Many Emperor Tetras Per Gallon?

Many aquarists use the “1 inch of fish per gallon” rule to help them select a suitable stocking level for their aquarium. As emperor tetras typically grow to 2 inches in length, you can add 1 fish for every 2 gallons of water.

A 10-gallon aquarium, for example, can house a maximum of 5 emperor tetras.

Water Parameters

Water Temperature72-81°F
Hardness3-8 dKH


The emperor tetra looks the most vibrant in low-light conditions, so consider reducing the brightness of your aquarium lights. Any fish tank light will do the trick for an emperor tetra aquarium, though densely planted setups will benefit from a full-spectrum LED light.

Floating plants will also help provide shade from your aquarium light.


The emperor tetra’s natural habitat is filled with dense vegetation, so you should try to replicate this in the home aquarium. These fish like to explore and hide, so adding live plants to your tank will help them feel safer and more comfortable.

Some good plants to include in your emperor tetra tank include Amazon sword plants, java moss, java fern, vallisneria, and anubias.

These plants provide ample cover and are easy to take care of, making them great picks for an emperor tetra setup.


You can also add Indian almond leaves to create a blackwater habitat for your fish, similar to their natural environment.


Opt for dark colored substrate in your emperor tetra tank to enhance the colors of your fish. Dark-colored sand, gravel, or planted tank substrates are a few great options.


This small freshwater species originates from slow-moving streams, so your filter shouldn’t have an overly strong current. Make sure your aquarium filter has an adjustable flow rate so you can decrease its current.

Temperament & Suitable Tank Mates

Black Emperor Tetra
Black Emperor Tetra

Tank mates

Emperor tetras are a peaceful species, so they can be housed in species-only aquariums or community tanks with other tetras and non-aggressive fish, even freshwater crabs such as the pom pom crab. They tend to stay at the top or middle level of the water column.

Are Emperor Tetras Aggressive?

Emperor tetras have a peaceful nature, so they are normally very docile. However, they can nip the fins of other fish (especially long-finned fish like bettas), particularly if kept in insufficient numbers.

In addition, males can be territorial towards one another, so it’s best to only keep 1 male per group.

Ideal community aquarium tank mates for an emperor tetra include cory catfish, pencil fish, other species in the tetra family, honey gourami, dwarf gourami, pearl gourami, aquatic snails, dwarf plecos, barbs, and rasboras. Peaceful dwarf cichlids can work as tank mates too. Avoid larger fish and overly boisterous tank mates.

How Many Emperor Tetras Should Be Kept Together?

Emperor tetras are schooling fish, so they do best if kept in groups of at least 5 with a single alpha male.

Alternatively, you can keep them in bonded pairs.

Can Emperor Tetras Live With Neon Tetras?

Yes, emperor tetras can live with neon tetras as they have similar water requirements and are both peaceful species.


Emperor tetra fish are omnivorous they need both meat-based foods and plant matter in their diet to thrive.

What Do Emperor Tetras Eat?

Emperor tetras aren’t picky when it comes to food – they’ll readily accept dry food, live food, and frozen food. In the wild, these small freshwater fish consume worms, larvae, insects, small crustaceans, and algae.

What to Feed Emperor Tetras

The main staple of the emperor tetra’s diet should be high quality pellets or high quality flake food targeted for omnivorous fish, alongside live or frozen foods such as brine shrimp, mosquito larvae, midge larvae, black worms, and daphnia.

Aside from pellets and flake foods, You can also feed them the occasional vegetable like zucchini, spinach, cucumber, and broccoli.

I personally feed these schooling fish floating pellets, live mosquito larvae, freshly hatched baby brine shrimp, and frozen fish food like frozen bloodworms, tubifex worms, and daphnia.


Variety is key for keeping these fish healthy, so offer them a wide range of different foods on a regular basis.

How Much to Feed Emperor Tetras

You should feed your emperor tetra fish as much food as they can eat within around 2 minutes. After this time, remove any uneaten food with a net to prevent overfeeding and fouling of the water.

When to Feed Emperor Tetras

Emperor tetras should be fed twice a day: once in the morning and once in the evening.

Do Emperor Tetras Eat Shrimp?

Yes, emperor tetras do eat shrimp, though usually only small species like cherry shrimp and shrimplets (baby shrimp). Larger species like bamboo shrimp and amano shrimp will generally be safe in a community tank with emperor tetras.


Emperor Tetra on a Planted Tank
Emperor Tetra on a Planted Tank

The emperor tetra fish is relatively hardy, but that doesn’t mean they can’t get sick. Emperor tetras are likely to develop health issues if housed in dirty conditions or tanks with the wrong water chemistry for this species.

How Long Do Emperor Tetras Live For?

With the right care, emperor tetras can easily live for up to 6 years. Feed your fish a variety of foods and keep their aquarium clean and stable to promote good health.

Common Possible Diseases

These fish don’t suffer from any species-specific illnesses and diseases, but there are a few health issues that commonly affect freshwater fish, in general, to look out for. These include fungal infections, bacterial infections, or parasite infections like ich, gill flukes, and dropsy.


Breeding the emperor tetra species of fish isn’t overly challenging as they will naturally spawn in captivity. However, there are a few things you can do to increase your chance of success, which I’ll be going over below.

Yes, emperor tetras are easy to breed as they will typically mate without intervention if kept in groups of females and a single alpha male.

How to Breed Emperor Tetras

Although emperor tetras will usually spawn naturally if kept in optimal conditions, you’ll yield a larger portion of eggs and fry if you move them to a separate breeding tank. Each male and female pair should have their own breeding tank to prevent aggression.

After placing them in separate tanks, condition each pair for breeding by feeding them live foods like daphnia, brine shrimp, and bloodworms for a few days. The breeding tank should have soft water with a pH of around 7.0.

Gradually raise the water temperature of the breeding tank to 82°F over several days to trigger spawning. Make sure the tank contains plenty of live plants to replicate a natural habitat too.

If your female emperor tetras become visibly rounder and plumper, that means they are ready to lay eggs. Spawning occurs at dawn, at which point the female will lay between 50 to 130 eggs over several hours while the male fertilizes them externally.

The parents will typically eat their own eggs, so you should move them back into your main aquarium once spawning is complete. The eggs will usually hatch within 48 hours.


If you don’t see any eggs after a few days, replace the breeding pair with a new pair.

Sexing Emperor Tetras

The emperor tetra is sexually dysmorphic, so it’s quite easy to tell males and females apart. Males are usually larger, more vibrant, and have longer dorsal fins and a bigger caudal fin. The tail fin also tends to be more trident-shaped.

Another way to distinguish between males and females is by looking at the eye color of the fish. Females normally have metallic green eyes and males usually have metallic blue eyes.

Breeding Tank Setup

The breeding tank for your emperor tetra breeding pair should be bare bottom (no substrate) to make it easier to clean once the eggs have hatched. You should also add floating plants (duckweed, frogbit, salvinia, etc) and bushy plants like java moss, java fern, and Christmas moss.

This will help create a natural environment for your fish to help them feel safe and secure. As tetra eggs are sensitive to light, make sure the aquarium is kept dark at all times.

Emperor tetra fry are very delicate and small, so a sponge filter with a gentle flow is ideal.

Emperor Tetra Fry Care

Emperor Tetra Fry

Emperor tetra eggs typically take around 48 hours to hatch. You don’t need to feed the baby fish for the first few days as they will consume their egg sacs.

Once the fry become free-swimming, feed them infusoria. As they get bigger, you can transition them to baby brine shrimp and commercial fry foods.

Perform weekly water changes on the breeding aquarium to keep conditions pristine. When the baby fish are around 2 months old, you can begin feeding them other live foods like adult brine shrimp, as well as freeze-dried and frozen foods.

At this age, they should be big enough to move into your main aquarium with your adult fish.

Is the Emperor Tetra for You?

If you’re looking for a peaceful, hardy, and vibrant fish species, the emperor tetra is the right fish for you. This species doesn’t have overly demanding care needs as they can be housed in nano aquariums and can adapt to a relatively wide range of parameters.

As they are schooling fish, you should keep them in bonded pairs or a group of at least 5, ideally with a single male. Due to their docile temperament, you can keep them with other fish in a community tank.

However, they can be nippy towards fish with long fins, even more so if they are not kept in schools. Select non-aggressive tank mates like other species of tetra, platies, cory catfish, small plecos, and rasboras.

Final Thoughts

I hope this guide helped you learn everything you need to know about emperor tetra care and, hopefully, encouraged you to give owning this freshwater fish species a try.

They’re one of my favorite species of tetra because of their gorgeous coloration! What do you like the most about the emperor tetra? Be sure to let me know over on our social media platforms, and share this post with your friends and family.

If you’re looking for more informative care guides on fish species or the best aquarium products on the market, check out our other articles.

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