How Many Blue Emperor Tetras Can I Put in a 10 Gallon Tank?

Written By Lewis German  |  Tropical Fish  |  0 Comments

Blue Emperor Tetra

Blue Emperor Tetras are great little fish to keep, they are active, interesting and hardy, ideal for beginners, and look brilliant in a planted tank.

But can you add Blue Emperor Tetras to your 10 gallon tank? Are they suitable in a small community tank? What goes into maintaining a Blue Emperor tank? And how many should you keep?

This and more we aim to answer in the article below:

How many Blue Emperor Tetras should be kept together?

Blue Emperors, like most Tetras are schooling fish, they are highly social and need to be kept in large groups if they are to do well in your aquarium.

We would suggest a number no lower than 5, this way they can form a small school, and will feel more comfortable in the tank.

Keeping fewer fish results in them being more skittish and stressed.

As these fish seek safety in numbers, the more you can keep the better, in the limitations of your tank size of course.

What happens if you add too many Blue Emperor Tetras to a 10 gallon tank?

Although Tetras like to stay in large groups, there is such a thing as having too many Tetras in your tank, and in a 10 gallon, overstepping the boundaries can happen.

More fish means more mouths to feed, more food means more waste and as a result more toxic ammonia in the water.

Unless you keep up with frequent water changes, then the level of waste can become too much and could cause a crash, killing all the inhabitants in your tank.

You may end up needing to perform water changes every day just to keep the waste level down, so unless you have a very powerful filter, and are willing to do lots of maintenance, adding 20 fish to your 10 gallon is probably a very bad idea.

How many Blue Emperor Tetras can I put in a 10 gallon tank?

As mentioned, Tetras like to stay in groups, but you can’t go and squeeze 20 fish into a 10 gallon, so how many Tetras should you add?

Ideally, Blue Emperors should be housed in a larger tank than 10 gallons, mainly because the extra space allows you to keep more of them, so that they may feel comfortable in a large group.

However, it is possible to house around 5 – 6 adult Emperor Tetras in a 10 gallon, but with this said, they will always do much better in a 20 gallon.

How many male Blue Emperor Tetras can I put in a 10 gallon tank?

Male Emperors can become quite territorial as they mature, and will spar with other males to assert dominance and acquire mating rights to females.

Unfortunately they can be difficult to sex until they are fully mature, so acquiring young fish can be a little risky.

Mature males however, are very obvious due to their bright colours, larger size and long finnage, so are very easy to pick out.

You ideally want to have more females than males in your Emperor tank, as a way to reduce competition, having a 1:2 ratio is best, perhaps 1 – 2 males and 4 females in a 10 gallon.

As they can be hard to sex when young, if you purchase a school of adolescent Tetras, chances are you could get a group that is particularly male heavy.

This is another reason why having a larger tank is better for Emperors, as it provides the males with enough space to avoid each other, if it so happens that you end up with a higher number of males.

How many female Blue Emperor Tetras can I put in a 10 gallon tank?

Females are not as territorial as the males, so you don’t need to worry about them having constant disputes over mating rights or space, although they can occasionally nip at each other or chase each other, a fight resulting in lasting damage is very rare.

If you have a mixed sex tank, then try to keep more females than males if possible, in a 1:2 ratio.

Can I breed Blue Emperor Tetras in a 10 gallon tank?

Yes, you can breed Blue Emperors in a 10 gallon, but you may need 2 tanks to do it, as one tank will be the “Bench” for the adults to live in, and another tank will be the breeder setup, where the conditions are set to induce spawning.

The adults are fed heavily and conditioned up in one tank, then moved to another, where they lay their eggs.

Once the eggs have been dropped, the adults are moved back to their Bench Tank and the resulting fry are raised in this 10 gallon breeding tank on their own

Alternatively, the parents can be spawned in one tank, the eggs collected and moved to another tank where they will hatch.

What is the best filter for a 10 gallon Blue Emperor Tetra tank?

Any filter will work well with Blue Emperors, so long as they output enough surface distortion.

Emperor Tetras are fish of the river, and are used to living in an environment with high oxygen levels, this must be replicated in the aquarium, so any filter that throws out a current, or is air powered works great, as it will break the surface tension of the water.

Hang on backs, internal or external pumps and sponge filters are all great options for your Emperor Tetra tank.

10 gallon Blue Emperor Tetra tank maintenance

Emperor Tetras output a fairly low Bioload because of their small size, however they do require just as much maintenance as any other fish.

Meaning that they need regular feeding, water testing, water changes and filter cleans.

When in a small tank, you may also have to watch for aggression amongst males, adding lots of cover in the form of live plants is a good way to reduce fighting.

If you have tankmates with your Emperors you may also want to make an effort to ensure that they are being properly fed too, as Emperors are fiercely competitive over food and will be the first ones to the top of the tank.

Can I keep other fish with Blue Emperor Tetras in a 10 gallon tank?

Yes, you can keep other fish with Emperor Tetras, but this is best done in a larger tank, as not to go over the limit on your filtration.

It would be difficult to house a school of 6 Tetras and another type of fish in the tank, which is why your 10 gallon tank would be best as a species only.

However, you can keep other species with Blue Emperors in a 10 gallon for a time, you just need to look for other fast moving, similarly sized fish.

Slow eaters and less confident species should be avoided, so that they are not outcompeted for food. 

Here are some recommendations of fish we like to keep with Blue Emperors:

  • Panda Corydoras
  • Zebra Danios
  • Harlequin Rasboras
  • Other small Tetras
  • Platies

Can I keep invertebrates with Blue Emperor Tetras in a 10 gallon tank?

Yes, you can keep some types of invertebrates with Blue Emperors, but not all species work for various reasons:


Cherry Shrimps

Blue Emperors can actually pair quite well with Cherry Shrimp, although the risk of them eating the young and newly mauled adults is still there.

Provided they have enough cover and plantlife, both species can coexist peacefully, and the Shrimp may be able to maintain a stable population amongst the dense plantlife.

This said, it would be a lot easier to do this in a tank larger than 10 gallons, as the extra space provides the shrimp with more areas to hide themselves.

Amano Shrimp and Bamboo Shrimp also work well with Blue Emperors due to their large size.

Remember to acclimate these shrimp properly and slowly, as they naturally come from slightly saline waters, and the move from brackish to freshwater can be a little tough on them sometimes.



All types of aquarium snails work well with Blue Emperors and we highly recommend some species as cleanup crew for your tank, namely: Ramshorn snails, Malaysian Trumpet snails and Bladder snails.

These snails do not eat plants, but will clean up after your fish, break down waste and will eat algae. Just be sure that you provide them with calcium from time to time in the form of a KH buffer, otherwise their shells can dissolve in slightly acidic water.

Crabs and Crayfish

Emperor Tetras are quite small and nimble, which makes them a difficult target for a large lumbering predator like a Crayfish, so it is entirely possible to keep them together with large crustaceans, however, in a 10 gallon, we would say no, as the space is simply too small for both species to coexist.