Emperor Tetra Fish Species Profile

Characteristics, Origin, and Helpful Information for Hobbyists

Emperor Tetra - Nematobrycon palmeri
Andy Jones

If you're looking for an attractive addition to a community tank, the emperor tetra may be your ideal choice. Not only is it a handsome, iridescent species with impressive reflective rainbow hues, but it's also a peaceful and hardy fish in a mixed community of South American freshwater fish. Emperor tetras are easy to find and relatively inexpensive.

Species Overview

Common Names: Emperor tetra, imperial blue rainbow tetra, rainbow tetra

Scientific Name: Nematobrycon palmeri

Adult Size: 2 inches (5 cm)

Life Expectancy: 6 years


Family Characidae
Origin Colombia
Social Peaceful
Tank Level Mid dweller
Minimum Tank Size 10 gallons
Diet Omnivore, eats most foods
Breeding Egg layer
Care Intermediate
pH 5.0 to 7.8
Hardness to 25 dGH
Temperature 73 to 81 F (23 to 27 C)

Origin and Distribution

These fish are native to the freshwater Atrato and San Juan River basins of Colombia in South America. They frequent areas that are slow-moving, such as small tributaries and streams, where the temperature ranges from 73 to 80 degrees Fahrenheit.

Though the emperor tetra is distributed over a narrow range in the wild, it has become a favorite aquarium pet and is farmed for sale around the world. As of 2014, the IUCN Red List (International Union for Conservation of Nature and Natural Resources) has insufficient data to determine the status of this species in its natural habitat in the wild; more research is needed. In captivity, the species breeds readily.

Color and Markings

The attractive coloration and elegant fins of the regal emperor tetra leave little doubt why the emperor tetra was given its name. Introduced to home aquaria in 1960, it has become one of the more popular of the tetra family of fishes. 

Fins of both sexes have a yellow hue and are edged in black on the outer periphery; they are red where the fin meets the body. The body of the fish is blue-gray with mauve tones, and it displays an almost iridescent sheen. A dark stripe runs horizontally from head to tail, and the body is lighter in color below the stripe.


A schooling fish, the emperor tetra does best in groups of five or six with a single alpha male, though it can thrive as a mated pair. It is also a peaceful species, and thus ideal for a relatively small community tank though it will be disturbed by more boisterous species.

Some compatible species include danios, rasboras, other tetras, and peaceful catfish species such as Corydoras or smaller Loricariids. Pencil fish and dwarf cichlids are also good choices, especially as they hail from the same general region. You may want to choose species that contrast visually with the colorful emperor tetra to create a palette that pleases the eye.

Emperor Tetra Habitat and Care

Emperors favor dense vegetation and subdued lighting that mimics the Colombian rivers from which they originate. Dark substrate and a heavily planted tank will go far to make them feel at home; these also provide a gorgeous backdrop to this species' brilliant colors.

Although peat filtration is recommended, they will thrive in even moderately hard water as long as it is changed frequently to maintain purity. These fish prefer quiet habitats and should only be kept with other peaceful species that share similar water requirements.

Emperor Tetra Diet and Feeding

In the wild, the emperor tetra feeds mainly on worms and crustaceans. Undemanding in terms of their diet, captive emperor tetras will readily accept flake foods, freeze-dried foods, and frozen foods. Live foods such as daphnia, mosquito larvae, and brine shrimp are especially relished and are excellent when conditioning breeding pairs.

Gender Differences

Unlike many of the tetra species that have a unisex appearance, male and female emperor tetras are easy to differentiate. The dorsal and caudal fins of the male are noticeably longer and more pointed than the female. Also quite noticeable in the male is an extended ray in the middle of the caudal fin that gives the tail the appearance of a trident. The female is also smaller and plumper in the body than the male.

Breeding the Emperor Tetra

Schools composed of approximately equal numbers of males and females will eventually yield one or more breeding pairs. Each breeding pair should have their own breeding tank, as the males become quite aggressive when spawning. Separate the male and female from each other for a day or two, and condition with live foods prior to spawning attempts.

Maintain the water temperature in the breeding tank at 80 to 82 degrees Fahrenheit, with a pH of 7.0. The water should be very soft. Place a spawning mop or some dense floating plants in the tank, and keep the lighting subdued. The breeding tank need not be set up with a substrate or any other decor. This will allow for ease of cleaning as the fry (baby fish) develop.

Spawning begins at dawn; eggs are laid singly over a period of several hours until fifty to one hundred eggs have been produced. The parents will often consume the eggs so the adults should be removed after spawning has completed. Use a sponge filter in the tank to prevent harm to the fry as they are growing. Perform water changes weekly.

The fry will hatch in 24 to 48 hours and will eat infusoria or other small foods such as freshly hatched brine shrimp. Water pH should not be allowed to become too acidic, or the developing young may be lost as the result of digestive disturbances.

More Pet Fish Species and Further Research

There are many different species of tetras, and all are similarly peaceful, attractive, and easy to care for. Many aquarists mix and match tetra species to create an interesting, active, and aesthetically pleasing tank environment. If you’re interested in similar species, check out:

Check out additional fish species profiles for more information on other freshwater fish.