Emperor tetra stats infographicThe Emperor Tetra is a handsome, iridescent species of freshwater fish that have gained a strong following over the years. This species has been revered in the aquarium hobby due to its regal looks. What is more, Emperor Tetras are quite resilient and a breeze to look after. Their peaceful disposition is another advantage to boot. As they are quite popular, Emperor Tetras are easy to find and relatively inexpensive, too.

To help you understand this species, we made sure to come up with a clear-cut Emperor Tetra care guide.

What Is an Emperor Tetra?

The Emperor Tetra is a species of characin fish native to the freshwater Atrato and San Juan River basins of Colombia, South America. These omnivorous fish inhabit sluggish tributaries and streams where the temperature ranges.

Emperor Tetra Stats

Nematobrycon palmeri
Common Names Emperor Tetra, Black Emperor Tetra, Imperial Tetra
Class Actinopterygii
Family Characidae
Genus Nematobrycon
Size 2.5 inches
Diet Omnivore
Temperament Peaceful but males can be aggressive during spawning
Lifespan 5 years
Strata Middle to upper levels
pH 5 to 7.8
Hardness 3 to 8 dGH
Temperature 73 to 81 F
Care Level Beginner

Emperor Tetra Care

Want to know how to provide your Emperor Tetra with the best diet and water conditions? Then read this section!


Emperor Tetras are undemanding in terms of their omnivorous diet. In the wild, adult fish survive on plant matter as well as worms, larvae, and tiny crustaceans. Captive specimens will accept quality commercial flake foods. Live foods such as brine shrimp, daphnia, mosquito larvae, and bloodworms are especially relished. Meaty foods are also preferable when conditioning breeding pairs.

Water Parameters

Emperor Tetras can adapt to a generous range of water conditions, but they favor warm and moderately hard water. To replicate the Tetras’ water conditions in the wild, you should aim for the following parameters:

  • Water temperature: 73 to 81 F
  • pH Level: 5 to 7.8
  • Water Hardness: 3 to 8 dGH

Change at least 10 percent of the tank water each week. As often as possible, use a vacuum gravel cleaner to pick up fish poop, dead plants, and food debris.

Tank Setup

Create the best aquarium to make your Tetras feel at home by reading this simple guide!

Tank Size

Emperor Tetras are perfect for any community tank regardless of the size as long as there are no large species of fish that may see them as food. A minimum of 30 gallons is recommended should you wish to include a few compatible species. If you plan on setting up a single-species nano tank, 10 gallons should suffice.

Plants and Decorations

Blue emperor tetrasA densely planted aquarium provides a wonderful backdrop to the brilliant colors of the Emperor Tetra. Plants also limit the intensity of the lighting used and provide hiding spots for your fish should they feel stressed. Moreover, live plants will bring balance to the ecosystem as they absorb nitrates. Make sure to wash and disinfect decorations before adding them to the tank.


As for the substrate, you will want to line the bottom of your tank with something dark to bring a beautiful contrast to the lush greenery and colorful fishes in the tank. The choice of plants, however, will dictate which type of substrate is best for your aquarium.

Gravel and sand are cheap options for planted tanks, but it is wise to steer clear of anything smaller than sand grade number three as they increase the risk of hydrogen sulfide buildup. If your budget allows it, opt for nutrient-rich specialized substrates, especially if you have root feeders. But if your plants are mostly water column feeders, then there is little point in using expensive substrates.

A multi-substrate layer is also recommended as it mimics a natural aquatic environment for your fish. Achieve this by adding a base of sand, a middle layer of aquarium soil, and top it off with a layer of gravel. The bottom layer provides an excellent base for plants to grow while the gravel will help stop smaller particles from clouding the water.


For tank equipment, you will need a low-powered light and a reliable hang-on-back filter (HOB.) filter.

Lighting can create a big difference in the coloration of any fish. If you wish to highlight the purple hues of these Tetras, opt for subdued lighting. The yellow undertones will otherwise dominate.

When it comes to filtration, one of your best options is the HOB, but you can go for a more efficient filtration depending on the size of the tank and the number of fish you have. As Emperor Tetras prefer slow-moving waters, make sure the filter does not generate too much flow. Position plants and other tank decorations to minimize water disturbance.


The Emperor Tetra lifespan can reach five years in captivity, granting that you keep on top of water quality, provide a high-quality diet, and pair your Tetras with appropriate tank mates that will not stress them out.

Common Diseases

Small fish are often considered to be hardier than large species of fish, but that doesn’t mean your fish is invulnerable to common ailments that affect freshwater fishes.

Beautiful tetras, in particular, are notorious for contracting the Neon Tetra Disease. This disease occurs when a Tetra consumes fish carcasses or live foods that act as an host for a parasite called Pleistophora hyphessobryconis. Once a Tetra ingests this parasite, it will eat your fish from the inside.

In Neon Tetra Disease, you are likely to observe symptoms in this order:

  • Restlessness
  • Loss of coloration in one part of the body
  • Cysts in the muscles develop
  • Difficulty in swimming
  • Fin rot and bloating

Unfortunately, this disease is irremediable, and the affected fish will most likely die. What you can still do is to quickly separate the affected fish to avoid spreading the disease. As the disease is highly contagious, you will want to check on the other fish and see if the same symptoms are manifesting.

Tank Mates

This species makes an excellent tankmate for the most readily available livebearers, danios, rasboras, and other peaceful bottom-dwelling freshwater fish, such as Corydoras and small species of Loricariids. Freshwater aquarium snails also coexist with Emperor Tetras.

Here are some fish species worth considering:

Avoid large species of fish that could mistake your Tetras as food.


Learn how to breed Emperor Tetras here:

Signs That Emperor Tetras Are Ready To Breed

Breeding may occur without any intervention if the school comprises approximately equal numbers of males and females. But because males compete aggressively during spawning, you will want to separate the males from the females temporarily. Then choose a breeding pair to add to a small tank. Emperor Tetras are slow spawners. Actual courtship and spawning will take several hours.

Aquarium Setup

The water should have higher temperatures than usual, ideally around 80 to 82 F. Likewise, the tank water has to be very soft with a pH of 7. Place a spawning mop in the tank and keep the lighting subdued. There should be no decorations or substrate to allow for ease of cleaning as the fry develop.


A female Emperor Tetra can lay up to 100 eggs over several hours. Once she is done, you will need to remove the parents as they will predate upon the eggs. The fertilized eggs will hatch in about two or three days. For the first week or so, the baby fish will feed on their protein-rich egg sac. Once they become free-swimming, you can provide them with infusoria. Feed the fry baby brine shrimp about a week later.

Emperor Tetra Facts


Scientifically known as Nematobrycon Palmeri, Emperor Tetra is so named in honor of Mervyn George Palmer, an English traveler, and collector. These fish were first imported in the aquarium trade to the United States in the ‘60s. Since then, these fish have become a staple in the community.

Although Emperor Tetra has a narrow distribution in the wild, it is not an endangered species. The International Union for Conservation of Nature and Natural Resources (IUCN) may have insufficient data to back up this claim, but Emperor Tetra is farmed in large numbers throughout the world.


Emperor tetra dietEmperor Tetras flaunt a slender bluish-gray body with mauve tones that have an iridescent quality. The undertones become more vivid in low-light conditions, thus creating a gorgeous purplish sheen. Just so you know, the purple color has been associated with royalty for centuries and therefore, the Imperial Tetra leaves little doubt why it is named as such!

Accompanying the beautiful base color is a prominent black stripe that runs from the mouth all the way to the tip of the tail. Looking at the fish closely, you will see a thin shimmering blue line atop the black stripe. This species has subtle details in its fins, as well. Both sexes have a yellow hue in their anal and dorsal fins and these may be accompanied by a tinge of red where the fin meets the body.

Gender Differences

There are many ways to tell males and females apart as Emperor Tetra is sexually dimorphic:

  • Males possess metallic blue eyes, while females have metallic green eyes.
  • Males appear slightly longer than females and they take on a more pointed shape. Females, on the other hand, look plumper, especially when ripe with eggs.
  • Males have a three-pronged tail, which resembles a trident. The medial black stripe usually extends beyond the rest of a male’s tail.

Color Morphs

The Black Emperor Tetra, also known as Nematobrycon Palmeri var. Amphiloxus Black, is not a separate species but a beautiful color morph of the classic Imperial Tetra. Instead of having a purplish body, it features a satin black coloration and finnage.

But apart from the color, there isn’t a huge difference between the Amphiloxus Black and the classic Emperor Tetra. These variants sport a pair of bright blue or green eyes, depending on the gender. Adult males also flaunt elongated dorsal and caudal fins that resemble a trident.

Behavior and Temperament

Emperor Tetras will dance around your aquarium in darting motions. These agile swimmers will occupy the middle up to the higher levels of your tank. Sometimes, they will also explore the bottom and examine the plants.

Are Emperor Tetras aggressive? Peaceful by nature, they reside harmoniously with most non-aggressive species. Keeping these fish in a large group goes a long way toward a serene community but, obviously, these tiddlers are in mortal danger if there are large species of fish.

Some hobbyists claim the Nematobrycon Palmeri to be a wee bit feisty when their numbers are insufficient. Therefore, it is wise to purchase a group of at least half a dozen. Better yet, buy 10 or more Emperor Tetras.

Emperor Tetra vs. Rainbow Emperor Tetra

The Nematobrycon Palmeri is easily confused with the Nematobrycon Lacortei, commonly known as Emperor Rainbow Tetra. The latter is a different species and this fish is a lot more colorful to boot. However, Emperor Rainbow Tetra is less often available in the trade.


Are Emperor Tetras Fin Nippers?

No, these Tetras do not nip at the fins of others. Little acts of aggression seldom occur and when they do happen, it is often due to males challenging each other for the Alpha role. On the bright side, these mock battles never amount to much.

Are Emperor Tetras Schooling Fish?

No, the Emperor Tetra is not a true schooling fish but this species has been observed to swim in unison when kept in large numbers. These fish will fare much better when they are maintained in a large group.

How Big Do Emperor Tetras Get?

The Emperor Tetra will grow around 2 inches in length when raised in an aquarium. While wild species can grow up to 2.5 inches, captive specimens will stay smaller regardless of the size of your tank.


Emperor Tetra is one of the most well-established species in the Tetra family. If you wish to make the emperor Tetra your next pet, be sure to remember the following points:

  • Emperor tetra care guideFor tank mates, you have plenty of choices, although the best ones are species coming from South America as they have similar preferences.
  • The omnivorous Emperor Tetra will accept commercial fish food but you will also want to provide them with live foods.
  • Emperor Tetras favor a tank with dense vegetation and subdued lighting as it mimics the Colombian rivers from which they hail.
  • The mauve undertones of Emperor Tetra will become more apparent in an aquarium with low lighting and floating plants on the surface.

Thanks to their easy-care requirements, Emperor Tetras make excellent pets even for novice fishkeepers. Now that you have done reading this care guide, you are ready to get some for yourself!

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