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Emerald Dwarf Rasbora Overview, Breeding, Facts & More

If you are thinking of housing some exotic and cute little fish in your tank, then Emerald Dwarf Rasbora or Pygmy Rasboras will be the best choice. As an intermediate aquarist, you will enjoy taking care of those tiny species in your tank.

Having the scientific name Danio Erythromicron, are popular species from Southeast Asia. These 0.75-inches fish are best kept in a group of 8 in a 5-gallon tank with proper vegetation and slightly acidic water. They live for 3-5 years and are readily available at fish stores.

Species Overview

Level of CareModerately difficult
AppearanceTheir body comes with a reddish base color, along with round black and dark brown spots on the sides.
Life Expectancy3-5 years
Tank Size5-gallon
Tank EnvironmentSoft acidic water with adequate hiding places
Tank MatesVery peaceful

Emerald Dwarf Rasbora or Danio Erythromicron is one of the most popular species in the aquarium trade. You can easily find these fish in South East Asia or on the Malay Peninsula, which lies in southern Thailand.

Also, they are easy to find in Eastern Sumatra and Singapore. Besides, these fish are abundantly found on the island of Bintan and the Riau Islands province of Indonesia. Some species are even found in lake Inle of South-Eastern Asia.

The freshwater fish, Danio Erythromicron, primarily inhabit the slow-flowing, dark water streams of black forests and rivers connected with peat swamps. Also, they are very easy to be found in ponds and ditches. These tiny cuties are often found hiding in the fallen leaf litter and branches.

Common Names

This Danio Erythromicron fish species is also well-known with other common names like Pygmy Rasbora, Dwarf Spotted Rasbora and Spotted Rasbora.



Generally, adult Pygmy Rasboras come with a slender body and small length. These freshwater fish look too attractive and exotic with reddish body color and round black and dark brown spots on their sides.

However, it has varied color patterns based on their origins. Some of them have a more intense variant of red. The males typically come with a cherry red and orange coloration. On the contrary, the female adult-size fish are relatively pinkish in color.


Emerald Dwarf Rasboras are usually too small in size, which makes them a much suitable species for a nano tank. This small fish species is not going to grow more than 1-inch or 2.5 cm. The average length of them is about 0.75-inches.

Usually, the largest individual among these fish reaches up to 2.5 cm in length and not more than that. The females are larger than the males.

Behavior & Temperament

Emerald Dwarf Rasboras possess a unique temperament. They are schooling fish and feel much more comfortable in their own species group. Also, these freshwater fish are great for a community aquarium.

Typically, these little fish are pretty peaceful by nature. But they can easily get stressed, as they are very sensitive. So, remember to provide them with appropriate aquatic conditions for their better living.

Besides, these rasboras even have the habit of hiding frequently. Thus, they serve to be great aqua pets for playing hide and seek in your leisure time.

Emerald dwarf asbora in aquarium


Emerald Dwarf Rasboras are pretty sensitive as aquarium fish. Thus, they do not live for long years. You can expect this fish species to live for at least 3 years. However, with proper care, adequate diet, and regular water changes, they can survive up to a maximum of 5 years.

Tank Requirements

As already said, they are usually schooling fish by nature. They love to hover around in all regions of the tank, and that is why they require ample space for swimming. But as they are too small in size, you need not opt for a too large tank; a moderate-sized one would be enough.

Besides, the tank water needs to have a stable condition. You can easily put them in a community tank with a well-established biological filter. To acquire proper water chemistry for your Emerald Dwarf Rasbora, you can opt for a peat filtration system, which will maintain the right balance in the water.

These fish tend to show their best color when you house them in a fine setup tank with soft and acidic water conditions. Moreover, using a darker substrate for your aquarium will let Emerald Pygmy Rasbora show better colors.

Also, an adequately aquascaped tank is considered to be the most suitable. Adding bogwood is a good consideration as it adds tannin levels to the water, which is essential for maintaining their natural habitat in the tank.

Also, make sure to add an adequate amount of decoration to the tank so that your tiny aqua pets can get enough place for hiding.

Tank Setup

To meet all tank requirements of an Emerald Dwarf Rasbora, you need to ensure that the aquarium has every essential assortment for taking good care of your fish at ease.

So, here is what you need to consider for facilitating the best tank setup:

  • Pick a minimum of a 5-gallon capacity tank for your tiny rasboras. For keeping more than 8 specimens of this species, you need to opt for a 10-gallon tank. Also, due to their small size, these fish are much suitable for any of the nano tanks.
  • You must also add a regular substrate to the tank. However, make sure the substrate is dark enough to showcase your rasboras’ glittery look.
  • For the tank, it is better to ensure subdued lighting. Too much bright lighting is not at all suitable for your fish.
  • Keep the temperature range of the tank on a scale of 74-79 ℉.
  • These rasboras usually prefer slightly acidic water conditions. So, try to maintain the pH range between 6-6.8.
  • These emerald dwarf tropical fish are fond of soft water parameters. Hence, it is best to maintain the hardness range of their tank within 1-12 dGH.
  • The aquarium water flow needs to be moderate enough for Emerald Dwarf Rasboras.
  • It is essential to include good plants in the tank so that these fish can have enough hiding places. You can add a few broad-leafed rosette plants. Also, you can consider adding some driftwood, roots, and branches of plants to the tank, along with java moss.
  • It is also much beneficial to add some dried leaves to aquariums. They grow microbe colonies in the tank, which work as a secondary source of food for Emerald Dwarf Rasbora

Tank Mates

Though emerald Emerald Dwarf Rasbora thrives well in a community aquarium, they are con-specific by nature. Hence, it is vital to keep these fish in a group of 8 specimens to make them feel comfortable.

Well, choosing suitable tank mates can be your real concern. These can easily get tensed and hide continuously when kept in association with other larger fish. Thus, the companion fish for your Emerald Dwarf Rasbora needs to have a similar size. It is better to house them with peaceful tropical fish species, which are not too active.

These are not at all safe with other semi-aggressive, aggressive, or large-aggressive fish. However, they safely reside with any shrimp, crab, or snail.

So, here are various suitable tank mates for emerald dwarf. Let’s have a look!

  • Cyprinid species
  • Trigonostigma
  • Microdevario
  • Eirmotus
  • Pygmy Corydoras catfish
  • Otocinclus

Food & Diet

It is not at all a hectic job to feed your dwarf Rasbora Danio Erythromicron. They will quickly eat any suitable fish food you offer them.

Emerald Dwarf Rasboras are omnivores in terms of feeding habits. In their natural habitat, they eat every type of tiny insect, worms, and zooplankton.

However, in captivity, these fish species need a varied diet. For maintaining the proper food and diet requirements, you can offer them flake food or tablet food that comes with natural pigments.

Also, you can provide them with highly nutritious fish food like spirulina algae and carotenoids. If you are thinking of offering them live fish foods, make sure it is too small to fit in their tiny mouths.

You can feed them daphnia or baby brine shrimp, which will be relatively easier for them to eat. Their diet must contain a proper amount of meaty food so that they can consume enough protein for living.

Now, are you wondering how often you should feed your tiny fish? Well, the best way to feed your Emerald Dwarf Rasbora is by offering them small quantities of food several times a day rather than giving too much food at once.

Provide only that much amount of fish food, which they can eat easily within 5 minutes. Otherwise, the excess foods will decompose in the aquarium, making the water impure and unhealthy.

Emerald Dwarf Rasbora Care

Caring is not a much tough job. However, you need to ensure that you maintain a decent quality of tank water to sustain their good health.

This fish species usually requires consistent water conditions in the aquarium. You need to keep the tank properly clean. For offering better care to your emerald dwarf, it is crucial to perform at least 25-50% of tank water changes once a month.

If you have dense vegetation in the aquarium, then at least 20-25% regular water change every alternate week is essential. Also, for keeping the fish tank clean and tidy, make sure you are vacuuming the substrate every time you perform a water change.

Emerald Dwarf Rasbora is not much more susceptible to freshwater fish diseases. However, they are quite sensitive to their environment and get easily stressed, which works as the main reason behind their diseases.

Emerald dwarf is also much sensitive to medications. Thus, if you ever feel the need to add medicines to the tank, make sure you are doing it very slowly.

If you are making any new addition of tank mates, substrate, or aquarium décors to the tank, ensure that the thing is properly cleaned. Also, provide with enough space for hiding and playing in the tank so that they can stay healthy and happy.

Breeding & Reproduction

Though caring for your dwarf Rasbora Danio Erythromicron is much easier, it can be slightly challenging to spawn them in a home tank. Generally, these fish are moderately difficult to breed.

To acquire successful spawning, you need to ensure that you are including proper assortments in their breeding tank, along with a dense plantation.

Emerald Dwarf Rasboras are popularly known as egg scatterers. If you are thinking of trying out a much-controlled spawning, then keep 2-3 pairs of fish in an adequately conditioned tank, along with facilitating them small offerings of live fish foods many times a day, for almost 4 weeks.

Also, conditioning them during breeding will help the males to acquire a brighter color. At the same time, well-fed female rasboras will produce healthier eggs.

While setting up the breeding tank, it is necessary to offer your little fish a very dimly lit environment with a low water level. For acquiring the most suitable breeding condition, the tank needs to have soft water with a 2-3 dGH hardness level.

Also, the water of the tank needs to be slightly acidic. Hence, try to maintain the pH value between 5.8-6.3. Also, it is essential to enhance the temperature of the water slightly.

To keep the water of the nurture tank for your Emerald Dwarf Rasbora much cleaner, you can add a small air-powered sponge filter. Also, peat filtration is another excellent option.

It is essential to have dense vegetation to acquire a proper tank setup for breeding. You can incorporate plants like milfoil or Cabomba for setting up an apt environment.

Most importantly, sexing dwarf rasbora is vital to achieving success in breeding under a proper spawning condition. Also, you need to add an appropriate spawning site to the tank. You can lay marbles or spawning mop on the substrate to save the eggs falling off the aquarium plants.

The adult fish species will take 1-2 weeks to get accustomed to the newer tank condition properly.

Emerald Dwarf Rasboras usually spawn in the morning hours in your aquarium. And they deposit around 50 eggs on the plants. And soon after eggs are laid, the parent fish are removed from the tank as they eat away fries.

Fries usually come out after 24-36 hours of spawning. In their initial days, they will easily survive on the yolk sac for at least 24 more hours. After that, these small fish will be able to do easy and free swimming.

You can easily feed them fish fry foods like infusoria or liquid fry fish foods. As these fries get larger, you can offer them crushed flake food or newly hatched baby brine shrimp.

Interesting Facts

There are some fascinating facts about Emerald Dwarf Rasboras that every fish-keeper must know before petting these fish. So, here is what you need to know about these tiny cute fish species.

  • The female Danio Erythromicron comes with a rounded belly, making it quite easier to recognize from the slimmer males.
  • The female Dwarf Rasboras are usually larger than the males.
  • The males of this species are much dominant during breeding and show intense coloration with brighter hues.
  • They are too active and dwell almost in all regions of a community aquarium.

Where to Buy?

When it comes to the availability of Emerald Dwarf Rasboras, they are not much readily available as other fish species in the aquarium trade. They are pretty rare in terms of availability in any random aquarist shop. Thus, you need to place your orders at the shop beforehand.

It is also quite expensive than other aquarium fish as they are small in size and much sensitive to getting transported. However, you can look for emerald dwarf in any of the hobbyist’s stores. Also, you can effortlessly search by their common name, Dwarf Rasbora or Pygmy Rasbora, and place orders on the online stores.

Wrapping Up

Emerald Dwarf Rasbora are pretty suitable for keeping in home aquariums. However, this freshwater fish can be a little bit difficult to pet for any beginner aquarist. Thus, they are mainly recommended for those intermediate aquarists who already have some prior experience in fish-keeping.

These fish are very sensitive to the tank environment. Also, they require a very stable tank condition. A sudden level of water change can turn out to be very harmful for them.

It is essential to house them with compatible tank mates and proper tank assortments; otherwise, they will get stressed quickly. Also, be very careful while deciding their diet during the breeding season as their spawning’s success depends on how well-fed they are.