Blue Emperor Tetra Care Guide

Written By Lewis German  |  Tropical Fish  |  0 Comments

What are Blue Emperor Tetras?

Blue Emperor Tetras, or Royal Tetras (Inpaichthys kerri), are a species of small, schooling South American Tetra with an active personality and striking colours.

They look good in any community tank, bringing extra life and movement, especially for that upper level of the aquarium.

Where are Blue Emperor Tetras from?

Emperor Tetras are found in the northern areas of South America, mostly in Columbia and some areas of Brazil, living in soft, acidic rivers and streams within forested areas.

In many fish stores today however, it is likely that the Emperors you purchase have been bred and raised in captivity on a farm.

Water parameters for Blue Emperor Tetras

As Emperor Tetras come from rivers containing plenty of decaying plant debris and mud, Emperors are accustomed to living in tannic water, with a low pH and hardness level.

Since they are a fish of the river, they also need plenty of oxygen present in the water, so a filter with a current or better yet, adding air stones to your tank is a good way to ensure they get the right level of oxygen and gas exchange.

pH6.0 – 7.4
HardnessLow KH and DH
Temperature25C – 28C (77F – 82F)
Ammonia (NH3)0 ppm
Nitrite (NO2)0 ppm
Nitrate<5 ppm

Feeding and diet of Blue Emperor Tetras

Blue Emperors are omnivores – they like to have a well balanced mix of foods and most of their diet consists of small invertebrates and any plant materials that fall into the rivers, like parts of soft fruits and veg.

In captivity, Emperors are very easy to feed, but benefit greatly from variety in their diet – offering many different food types can improve their health dramatically.

Flakes, algae wafers, frozen or live daphnia and bloodworm, as well as the occasional boiled cucumber or broccoli, will provide your fish with the nutrients they need.

Best tank mates for Blue Emperor Tetras

Blue Emperors are peaceful fish, although they can be a little boisterous at times and are always quick to eat all the food you put in the tank.

For this reason, while they are peaceful, we can’t recommend any fish that struggle when competition over feeding arises, so poor swimmers and slow eaters have to be excluded if you want both species to do well.

This list contains a handful of fish that can put up with competition over food, while still being peaceful:

Siamese Algae Eater (SAE)

Siamese Algae Eaters, not to be confused with Chinese Algae Eaters or Siamese Flying Fox, are a type of freshwater shark. They are related to Carps and Minnows and their primary diet consists of algaes and plant matter.

They are great for cleaning up algae on plants, rocks and glass, keeping your tank looking clean.

They are also quite powerful swimmers and will be able to get to food despite how quickly the Emperor Tetras may eat it.

They do however, get quite large (around 8”) so need a larger tank of around 50 gallons or more to be housed with comfort.

However, if you do have a large tank, they are ideal, they like water conditions similar to the Tetras, can compete with them for food and are amazing to watch.

Other Tetras

What fish works best with Emperor Tetras, are of course, more Tetras. Accepting that they are found in similar environments, they will have similar water needs, the same diets and have similar temperaments.

Mixing Tetras can be quite fun, but you need to know which ones are ideal to go together, so here are some examples:

  • Lemon Tetra
  • Diamond Tetra
  • Black Neon Tetra
  • Cardinal Tetra
  • Red Eye Tetra
  • Glowlight Tetra
  • Black Phantom Tetra

Make sure that when you buy Tetras, that they are from a healthy batch. Disease can spread easily among Tetras, so quarantining the fish is ideal if you have multiple tanks.

German Blue Ram

Rams are a type of South American Dwarf Cichlid that thrives in warm, tannic, acidic waters, much like the Emperor Tetras do.

They are effective swimmers, and can really move when they want to, especially when it’s feeding time. 

Rams can be territorial however, so they like to have their own space they can defend. For this reason, we recommend larger tanks when keeping Rams in communities – anything upwards of 25 gallons is best.


Of course Emperors are not limited to other soft water fish, and can be housed with livebearers too.

Platies are great because they are equally as boisterous as the Emperor Tetras, and will have no issue competing with them for food.

Both fish are peaceful, but are also both perfectly capable of holding their own, so fin nipping isn’t a worry either.

You will need to balance your water parameters however, in order to accommodate the preferred hard waters that platies need.

If you keep Emperor Tetras with any Livebearer, maintain a pH above 7.0 and keep a moderate hardness level.

How to breed Blue Emperor Tetras

Emperor Tetras are commonly bred in farms to be sold in aquarium stores, and have actually been bred into different colour morphs, such as the Black Emperor Tetra.

They can also be bred in the home aquarium fairly easily, as long as the conditions are correct.

Like other Tetra species, Blue Emperors lay eggs within mosses, dense foliage, leaves and rockwork, which will then hatch on their own some days later.

To induce spawning, feed the adults well over a period of days or weeks to put weight on them, then separate the fish into groups or pairs and place them into another tank, or introduce a spawning mop to the main tank which can be later removed.

Keep the water acidic and soft, adding tannins from driftwood or dried leaves can help greatly.

By increasing the temperature and performing a partial water change, they can sometimes be triggered to spawn.

However, for them to breed at all, you need a male and female.

How to sex Blue Emperor Tetras

Emperor Tetras are sexually dimorphic, so it can be easy to tell which are male and which are female.

However, they only show their characteristics when fully mature. The fish you purchase from the shop will often be too young to tell, but there are differences you can look out for to easily spot maturing males.

  • Male Emperor Tetras have more splendid colours and are larger than the females. They also have more exaggerated finnage on their dorsal and anal fins, which they flex high up when displaying.

The male caudal fin also has extremities and is more pointed / narrow than the female’s tail.

Rationing Blue Emperor Tetras

In the animal kingdom, a telltale sign that a male competes for a mate, is the fact that he is often larger than his female counterpart.

Emperor Tetras are indeed competitive for mating rights and will spar quite aggressively amongst themselves when they feel they want to breed.

They will also harass and chase females around their preferred spawning site, in order to ensure that their genetics are spread the most.

Because of their mating rituals, it is best to have one male to breed from and a group of females, much like a rooster and a group of hens in a harem.

You may also pair off individuals or have so much cover and space, that the adults can get out of eachothers way when spawning begins.

However, it is always best to play it safe, and make sure that you at least have more females than males; a 1:3 ratio is best.

Blue Emperor Tetra spawning and fry

After the eggs have been laid, Emperor Tetras will show no care for their young and will eat the eggs and fry shortly after producing them.

It is important to remove the eggs or the adults if you want to keep them alive.

After around 2 days, the eggs will hatch into wigglers where they will rest and absorb their yolk sack for the next 3 days.

After 3 days are up, they will develop into fry and begin looking for food. The best foods for fry are infusoria, live baby brine shrimp, walter worms and eventually crushed fish flakes.

They need to be fed at least 2 times a day, and need to have very clean water in order to be raised successfully, so they can be a lot of hard work.

What tank size do Blue Emperor Tetras need?

Blue Emperors are highly active and social fish, so they need enough space to move around in their schools.

For Blue Emperor Tetras, we recommend at least a 20 gallon aquarium. You may be able to squeeze a handful of them into smaller tanks, but once they mature, they will need extra room and a 20 gallon provides enough space for you to house a good amount of them.

What plants are best for Blue Emperor Tetras?

Emperor Tetras do well with any plants. They are excellent additions to planted aquariums but they do, however, appreciate tall leaf plants and reeds which they can hide amongst on the top level of the tank.

Here are some plants that grow tall, or float at the top of the tank, providing ideal cover for your Blue Emperors:

  • Jungle Val
  • Brazilian Pennywort
  • Salvinia
  • Dwarf Aquarium Lily
  • Anubias barteri

Tips and tricks for Blue Emperor Tetra care

A tip for keeping any Tetras that will highly benefit Blue Emperors is to use driftwood. The tannins produced by driftwood simulate their natural habitat in South America and provide several benefits to your aquarium.

Tannins soften the water, lower the pH and help to remove ammonia. They also have healing properties and prevent fungus.

Although your tank may be stained a little brown, the Tetras will greatly benefit from its presence.