Emerald Dwarf Rasbora: The Ultimate Guide

Emerald Dwarf Rasbora (Celestichthys Erythromicron) is a pretty fish that looks exotic and cute. These are underrated freshwater fish that would be a great addition to many aquariums and brighten them up.


For some reason, information resources are slightly deficient for these fish species in fishkeeping. So, we decided to make a comprehensive guide if you’re considering putting them in your aquarium.

Check this guide out for all the necessary details about Emerald Dwarf Rasbora.

It details their appearance, size, lifespan, care, feeding, breeding, and possible tankmates. We also included an FAQ section below for any questions you might have left unanswered.

So keep reading to learn more!

Emerald Dwarf Rasbora: Overview

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Emerald Dwarf Rasbora (Celestichthys Erythromicron) is a tiny fish you can find in South East Asia, Singapore, and Eastern Sumatra. These are one of the most popular fish in the world of fishkeeping, and some species are also found in the Riau Islands province of Indonesia.

Check below for basic details about the Dwarf Emerald Rasboras.

Appearance and Behavior

The first thing you will notice about these fish is their tiny size and the many beautiful details on their body. Dwarf Emerald Rasbora has a slender and long body with shimmering eyes on the surface of their heads and mid-transparent scales in the gill plate area.

You will find that this fish species is usually orange or coral pink in color and would be an excellent choice for tanks with a plant-covered or dark background. Many people prefer using a well-planted tank.

The Rasbora has thick emerald green stripes on the base color that shines when exposed to light and forms a wonderful display.

You should know:

The fish’s stripes and background colors could vary, and some might show as blue or purple.

A big dot on the two sides of their body (at the base of their tail) acts as a type of mimicry for tricking predators in the wild because it resembles an eye.

Bottom line:

How Do You Differentiate Between the Male and Female Rasbora?

Adult males are generally smaller than females, but you might not notice because of their typically small size. Apart from the size differences between them, the male species of this freshwater fish are vibrantly colored. These vibrant colors affect the stripes, fins, and base colors. Also:

Males typically have orange or red fins, while females have transparent ones.

Average Emerald Dwarf Size

An adult-sized dwarf rasbora fish should be between 1 – 1.5 inches in length. They aren’t huge fish which makes them a good choice for nano tanks.

When they’re young on purchase, these fish might only be half an inch in size. However, they have a steady growth rate and should reach their adult size in a short time.

Bottom line:

How Big Do Dwarf Rasboras Get?

These are generally small fish that do not grow to any considerable size. You’ll be hard-pressed to find one that exceeds the size of 1.5 inches, and its average length is 0.75 inches.


Healthy dwarf rasbora fish can live for up to 3 – 5 years. This is an acceptable life expectancy among fish of similar size.


To make these fish live up to this life expectancy, you need to ensure pristine living conditions, so they’re healthy. If you don’t take care of them adequately, they are exposed to many diseases and might die long before reaching their expected lifespan.

Emerald Dwarf Rasbora Care

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Taking care of these fish is relatively easy, and you shouldn’t have any significant issues if you cater to their water and tank requirements. They can easily adjust to a large range of water conditions without having any problems.

Even with that, you need to take care of them properly if you wish for the emerald dwarf to blossom in your aquarium. It would help if you worked towards providing a nicely decorated aquarium, high-level quality diet, and stable tank conditions, so they’re healthy and can safely enjoy free swimming.

Tank Size

Since the fish are small, you don’t need a lot of space in your aquarium to keep them. At the minimum, please keep them in a tank of 10-gallons as it is enough to make sure they stay healthy.

If you want even better results, you can go more significantly to a tank of 20-gallons. The space it provides will let you keep about 24-30 fish in one aquarium and give them enough space for swimming.

Water parameters

Emerald Dwarf Rasboras have a unique natural habitat that might be difficult to replicate. They have very clear waters, and Lake Inle – one of their naturally found homes – stays in a land valley that is about 900m below sea level.

The conditions of their natural habitat have made the fish more favorable to cool temperatures with pH levels that are neutral. This fish species will do very badly if you place them in acidic water, therefore it’s best to be safe and try to attain mildly alkaline pH levels.

You can use the following parameters in preparing and maintaining your aquarium so your fish shouldn’t have any problems with the conditions:

  • Water Temperature: 70oF – 75oF
  • Water Hardness: 2 – 10 dKH
  • pH level: 7.0 – 8.0

Tank Decoration

These are small fish species, so they need plenty of space to hide. Putting many decorations and dense vegetation is necessary for the fish. They tend to use rocks, plants, and other tank decorations for shelter anytime they are threatened or playing in an aquarium.

If you place them in a light aquarium with no vegetation or decorations, they tend to be more stressed. A lively and natural environment like their habitat makes them relaxed and confident for swimming around.

Mix up the live plants you want to put in the aquarium. Only select plants that you know will survive in their natural habitat in line with your set’s water parameters.

Select floating and leafy plants as they shade for hiding, and the fish can take cover. Driftwood is also a great addition to their tank as long as it isn’t leaf debris or natural driftwood that will release tannins into the water.

Bottom line:

Make sure whatever you put in the aquarium doesn’t colorize the water, and it remains clear at all times.

Use dark/black colored substrate at the bottom of the aquarium. This helps to mimic the loamy substrate of their natural habitat and brings out the fish’s natural colors.

We would advise you to use sand instead of other substrates like gravel for safe conditions.


Since you will need to ensure the water in the aquarium stays clear, you should get a reliable and quality water filter that can purify it. It will prevent the buildup of ammonia, nitrates, and other waste materials to make sure the water is pure.

You can also consider buying testing kits to keep an accurate check of the water conditions, so it is ideal for your fish.

Feeding Emerald Dwarf Rasbora

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Dwarf Emerald Rasbora are omnivores which means they will eat pellet foods and commercial flake. Another option you can give this fish is algae as they are passive eaters too.

In their natural habitat, their diet is protein-rich and typically includes insects. In your aquarium, try to make dry food their primary nutrition source. Always choose foods that have a proper nutrition balance for the best health and sustainability.

If you want to amplify the natural vibrant colors of this emerald dwarf, color formulas are the path to go, and they will get your fish sparkling.

Even though Dwarf rasboras will eat almost anything most of the time, sometimes they get picky, and dry food might not be enough for them. It would help if you also tried to give them high-proteinous snacks sometimes to keep them enriched and healthy.

Freeze-dried or live foods would work. Examples of some of these are:

  • Bloodworms
  • Mosquito larvae
  • Daphnia

Small algae wafers in their diet will also help satisfy a need for vegetable matter.

You might be wondering: The emerald dwarf is tiny, so how do you know how often to feed them?

The best way to feed small freshwater fish is by giving them small quantities spread out several times a day. This is opposed to giving them a lot of food at once as this isn’t optimal.

Only give them food they can finish quickly in 5 minutes. If you give them too much, they will sink to the bottom, decompose and make the water impure.

Their Tankmates

Dwarf Rasboras usually live peacefully with other freshwater fish species as long as they aren’t aggressive. They are usually not aggressive fish, and they do not eat one another.

In selecting tank mates for them, you should stay away from any fish that are too big or even a little bit aggressive. The best tankmates are those that have their origins and habitat in the same or similar region of these fish. Check out some fish that would make great Dwarf Rasboras tank mates:

  • Glowlight Danio
  • Cherry Shrimp
  • Sawbwa Bard
  • Small barbs
  • Dario Hysginon
  • Deviations
  • Red Dwarf Rasbora

Additionally, any type of small catfish and many freshwater snails would have no trouble living in the same tank as Rasboras.

Bottom line:

Is Emerald Dwarf rasbora with Shrimp?

You can also put them in the same tank with many shrimp species as long as they are not too big.

Is Emerald Dwarf rasbora with Betta?

These Emerald Dwarf are not ideal for staying in the same tank with bettas because bettas are a bit aggressive.


Emerald Dwarf Rasboras love to spawn and will even do that without your intervention as long as the conditions in the tank are ideal. By nature, they spread eggs and do not have parental instincts of any sort, which will make it easy for you to breed them.

The best way to ensure survival with breeding Rasboras fry is by using strictly controlled conditions. Build a separate building container and set all of the ideal conditions for their survival before adding the pair of bonded fish or groups.

Continue feeding them, and they should spawn naturally. The eggs hatch in approximately 72 hours and new fish fry is usually okay depending on the egg sac for 3-4 days before they start swimming. Get ready to feed them with Infusoria powder after they have hatched until they’re mature for brine shrimp.


Are Emerald Dwarf Rasboras fin nippers?

They are not usually fin-nippers, but although you might see some aggression in the male species. The attack isn’t usually severe and usually does not lead to any serious injury.

Dwarf rasboras tend to leave the other species in the tank alone and flock together with fish of the same species. Keeping these fish in large groups could help dissipate any aggression and let them live together more peacefully.

How Many Dwarf Emerald Rasbora Are There?

There are slight variations of the Emerald Dwarf Rasboras fish, depending on their source. The Boraras maculatus is a freshwater variant typically found in slow-flowing and dark water streams of black forests and rivers with links to peat swamps. You can find this variant in ditches and ponds or hiding in branches and fallen leaf litter.

You might notice slight variations in their colors and length. This usually indicates the region of the fish you are purchasing. However, they do also have a lot of similar features.

Can You Put Emerald Rasbora Fish in a 5-gallon tank?

Since they are small fish, the Rasboras fish can fit in a nano tank of about 5 gallons in size upwards. However, we wouldn’t recommend you do such and instead suggest that you keep them in a tank of at least 10 gallons.

If you keep them in a minimum tank size of 10 gallons, you can keep up to a group of six fish. While considering purchasing these fish in your tank, you should remember that they love to swim, and a larger tank is always better for them.


If you’re considering giving them tankmates, then you should go for larger tank sizes of 20 gallons upwards.

Where Can You Buy Dwarf Emerald Rasbora?

These fish are not as readily available as other freshwater fish species like bettas or goldfish but rare as some other obscure fish. If you’re lucky, you might find it in your regular aquarist shop. The most likely cause is that you have to place your orders at the shop beforehand so they can help you source the fish.

Other places you can purchase this freshwater fish from are online stores. Sometimes they might use different names for the fish like Pygmy Rasbora, but you shouldn’t encounter many difficulties purchasing it online.


Try Emerald Dwarf Rasbora Yourself!

Emerald Dwarf Rasbora is a secret gem in fishkeeping that deserves more attention than it is getting. They are beautiful, easy to care for, and do not need any special requirements.

If you are planning on getting one for your tank, this guide should help provide you with everything you need to know for taking care of them.


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