Emperor Tetra Care (Nematobrycon palmeri): Diet, Habitat & Breeding

Emperor tetra.
Emperor tetra. Citron, CC BY-SA 3.0, via Wikimedia Commons

The Emperor tetra, also known as the Nematobrycon palmeri, is popular amongst fishkeeping hobbyists.

Endemic to Columbia, the Emperor is a freshwater fish that thrives in dimly-lit and densely vegetated.

Typically, Emperor tetra lives between 2 to 4 years when living in adequate conditions.


The appearance of Emperor tetras is quite unique. The most prominent feature of the Emperor is its thick dark line that spreads from the mouth, lateral line, all the way to the tip of its caudal fin. Atop the lateral line, Emperors show pale coloration, which oscillates between blue, green, silver, and sometimes red. The Emperor has big fins, which remain sturdy as it swims around.

Emperors are sexually dimorphic. This means that males and females will have different characteristics. For example, the eyes of male Emperors are generally blue while those of females are green. The Emperors’ dark line is usually bigger for males than females.

Emperors are big relative to other tetras. Generally, when sexually mature Emperors are within the range of 5 to 6.5 centimeters in size, or 2 to 2.5 inches.

Habitat & Tank Condition

Juan R. Lascorz, CC BY-SA 3.0, via Wikimedia Commons

Tetras are schooling fish and like to stay in groups. Due to this behavior, it is important that your aquarium has a total of at least 6 tetras of the same species. To provide enough space for that many fish, you should have an aquarium that can hold at least 10 gallons.

The Emperor tetras, native to South America, prefer temperatures within the range of 22 and 26 degrees Celsius, or 72 to 80 degrees Fahrenheit. This can be done using an aquarium heater.

Water hardness should be kept as low as possible, preferably under 3 dGH.

We generally recommend the Fluval-E or the EHEIM Jager. These are great heaters that will work perfectly with most setup while providing accuracy and durability.

The Emperor tetras are generally found in slightly acidic bodies of water, ranging between 6 and 7. This can be achieved using blackwater extracts, botanicals such as Indian almond leaves, or pH buffering products like the Seachem Acid buffer.

As with all fish, it is recommended that you equip your aquarium with a filter. This will ensure the health, longevity, and happiness of your tetras.


Emperor tetras are omnivorous and will eat anything you give them.

It is recommended that you feed your fish a varied diet. This will ensure that your fish absorbs all the nutrients that it needs.

The great majority of their diet should consist of dry foods like flakes, pellets, granules, crisps, and algae wafers

Their diet should be complemented with protein foods, including brine shrimp, infusoria, bloodworms, tubifex, earthworms, and daphnia (water fleas).

Since Emperor tetras have small mouths, it is recommended that you break up their food into smaller pieces if you think it is too big.

You should feed your fish twice a day. To avoid overfeeding your fish, give them enough food for them to eat for 5 minutes. If the fish are still eating once 5 minutes have passed since the start of feeding, then you have overfed them. Adjust the amount you give them next time.


Emperor tetras with Neon tetras.
Emperor tetras with Neon tetras. Sitron, CC BY-SA 3.0, via Wikimedia Commons

Emperor tetras are peaceful when living in a community tank. When compared to other tetras, like Neon tetras, for example, Emperors are much larger. Due to this, they may be a little more prone to nipping other fish in the aquarium. However, this is usually caused by stress. The best way to make your Emperors feel at ease, it to put them in groups of 6 or more.

Since they are schooling fish, they much prefer to swim about the aquarium in groups of their own species. By reducing their stress, fishkeepers may drastically reduce the risk of them showing aggression towards other fish.


Emperor tetras can be difficult to breed. Females are not always willing to spawn. Success is relative to the breeding pair’s level of engagement.

To ensure the best possible setup for breeding, you will need to establish a breeding tank.  Ensure that you provide enough vegetation as this will put the fish at ease and encourage spawning. The pH of the water should be slightly acidic, preferably between 5.5 to 6. The water hardness should be as low as possible, with a dGH below 1.5.

When you first introduce the pair to the aquarium, make sure to close the light of the aquarium and if possible, surround the around with paper to prevent light from entering. A few days later, begin to increase the amount of light very slowly in the aquarium. This will encourage the pair to spawn.

Eventually, the pair will spawn, typically between 50 to 100 eggs. At this point, you will want to remove the pair from the aquarium to prevent them from eating the eggs.

The eggs will take 24 to 36 hours to hatch. You should expect a hatch rate between 25 to 50%.

Once hatched, the fry will remain near their eggs for a few days as they feed on yolk sack. Soon enough they will begin to swim around in the aquarium. You should then begin to feed them live foods like infusoria or commercially available prepared foods specifically made for fry fish.

You will be able to feed them bigger foods, like brine shrimp, 2-3 weeks later.

Make sure to keep the lights of the aquarium low, as the eggs and the fry are sensitive to light.

Leave a Reply