Emerald Dwarf Rasbora 101: The Complete Care Guide

Emerald Dwarf Rasboras are a beautiful freshwater fish that are seriously underrated. For whatever reason, they just aren’t that popular.

And we don’t get it.

This species is peaceful, easy to care for, and gorgeous. Watching a bunch of them swim around your aquarium is a sight to see!

This guide will teach you everything you need to know about proper Emerald Dwarf Rasbora care. By the time you’re done reading it, you’ll be prepared to own some yourself.

Species Summary

If you want to fill your aquarium with color and life, consider the Emerald Dwarf Rasbora! Scientifically known as Celestichthys erythromicron, these are tiny fish with big personalities.

In a well-decorated environment, these freshwater fish are highly active and curious. You can often see them playing or sparing with others.

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The Emerald Dwarf Rasbora is endemic to Lake Inle in Myanmar. This clear and shallow lake is rapidly changing, putting wild populations at risk. Luckily, this species is eager to breed, resulting in healthy numbers in the aquarium trade.

Thanks to their small size and beautiful color, these fish make excellent additions to tanks big and small.

Average Emerald Dwarf Rasbora Size

The average adult Emerald Dwarf Rasbora size is between 1 and 1.5 inches in length. These fish aren’t very big at all, making them a great species for nano tanks.

When you purchase them young, they’ll likely be only half an inch or so in size! These freshwater fish have a steady growth rate and don’t take long to reach their maximum length.

Author Note: Adult males are generally smaller than females. However, their small size still makes it challenging to tell the difference.


The lifespan of a healthy Emerald Dwarf Rasbora is around three to five years. This is quite a reasonable life expectancy for a fish of this size.

Because they are so small, these fish need pristine living conditions to stay healthy. Without adequate care, they can become prone to various diseases and die long before they reach their expected lifespan.


Emerald Dwarf Rasboras might be small, but they still have a lot of beautiful details that catch the eye! While we can describe it to you, you really need to see them in person.

These fish have long and slender bodies. On their heads, you’ll notice large shimmering eyes and semi-transparent scales around the gill plate.

Two Emerald Dwarf Rasboras swimming in a freshwater aquarium

The body of this species is typically coral pink or orange. These colorful fish stand out beautifully against a dark or plant-covered backdrop.

Covering that base color are several thick stripes of emerald green. The color shimmers in the light, creating a beautiful display as the fish swim around the tank. The stripes can vary a bit in color. Some will appear more purple or blue.

At the base of the tail, these fish have a large dot on both sides of the body. This dot is a form of mimicry. It looks like an eye, which can trick predators in the wild.

Author Note: There are a few notable differences between males and females beyond size. Typically, males are more vibrantly colored. This applies to the base color, stripes, and fins. Males have red or orange fins. Meanwhile, the fins on the females are usually transparent.

Emerald Dwarf Rasbora Care

Emerald Dwarf Rasbora care is fairly easy as long as you’re aware of their main tank and water requirements. This is a species that can adapt well to a range of conditions without any issues.

That said, you must take the job of caring for them seriously if you want them to thrive! Emerald Dwarves need stable tank conditions, a well-decorated environment, and a high-quality diet to live a healthy life.

Follow the basic care guidelines below to keep your fish in great shape!

Tank Size

As a dwarf-sized species, these fish don’t need a ton of space to stay happy. At the very least, you should keep Emerald Dwarf Rasboras in a 10-gallon tank. That’s suitable for a pretty healthy collection of fish.

However, we recommend keeping them in a 20-gallon tank for even better results. The extra space will allow you to keep a shoal of 24 to 30 fish and provide everyone with more room to swim.

Water Parameters

The natural habitat that Emerald Dwarf Rasboras occupy is unique. They come from crystal-clear waters, but Lake Inle rests in a valley that’s about 900m above sea level.

Because of this, the Emerald Dwarf Rasbora prefers cooler temperatures and neutral pH levels. This species does not do well in acidic water, so it’s best to err on the side of caution and aim for a slightly alkaline pH balance.

Stick to the following water parameters and your fish should have no problem acclimating to your tank:

  • Water temperature: 70°F to 75°F
  • pH levels: 7.0 to 8.0
  • Water hardness: 2 to 10 dKH

Author Note: Make sure to invest in an accurate and reliable aquarium water test kit to keep an eye on these parameters. Being informed on the state of your aquarium is incredibly important if you want to provide top-notch care.

Decorating Their Tank

Dense vegetation and plenty of decorations are a must for this species, since Emerald Dwarf Rasboras need places to hide. They use plants, rocks, and other decorations to take shelter.

When they are kept in a sparse tank, they may exhibit more skittish behavior (and live in a constant state of stress). A more natural and lively environment gives these fish more confidence to swim around.

Get a healthy mix of live plants to support this behavior. You can use any plant that can survive in this species’ natural living conditions (reference these care guides to make sure). Aim for leafy plants and floating plants. These fish will hide and play among the greenery.

Celestichthys erythromicron in a well-planted tank

You can also add driftwood. However, avoid any natural driftwood or leaf debris that could release tannins. Remember, these Emerald Dwarf Rasboras come from clear waters. Tannin-stained water is not something they will tolerate much of.

At the bottom of the aquarium, use a dark-colored substrate. This will not only bring out their color, but it will also mimic the loam substrate of Lake Inle. Use fine sand rather than gravel for safety.

Another important thing to consider is the filtration. These fish prefer to stay in large groups, which results in a lot of waste. Choose a filtration system with a water flow that’s four or five times the volume of the tank. This ensures that the tank is efficiently cycled to remove any ammonia and nitrates.

Common Possible Diseases

Emerald Dwarf Rasboras can suffer from all of the standard freshwater fish diseases. This includes Ich, parasitic infections, and swim bladder disease.

Ich is a common, yet dangerous, disease that’s usually caused by poor water conditions. White itchy spots form all over the body. If left untreated, fish can die from Ich. To make matters worse, it’s highly contagious and can quickly spread throughout a tank.

Skin flukes are another concern. Flukes are tiny parasites that latch onto the skin or gills. The infection could lead to labored breathing, so it’s important to treat the disease as soon as possible.

Swim bladder disease is one of the more alarming ailments these fish can experience. Bacteria harms the swim bladder, which affects the fish’s buoyancy and swimming ability.

Author Note: The good news is that treating all of these diseases is pretty straightforward. Over-the-counter medications and quarantining should usually address the issue and put your fish in good health again.

Food & Diet

Emerald Dwarf Rasboras are omnivores. They will accept most commercial flake or pellet foods. These fish are also passive algae-eaters.

Dry food should be the main source of nutrition. Go for foods that are nutritionally balanced for good health. You can also look for color formulas that help bring out the natural vibrancy in these fish (be careful when researching these brands though).

Emerald Dwarf Rasboras can get picky sometimes. While they will accept dry food, they usually prefer high-protein snacks much more. Because of this, it’s a good idea to provide them with some on occasion. It will provide enrichment and help them stay healthy!

You can feed them either live or freeze-dried foods. Some foods to try are daphnia, bloodworms, and baby brine shrimp.

Behavior & Temperament

As a peaceful species, the Emerald Dwarf Rasbora gets along well with most other fish.

However, they prefer to stick with their own kind. They’re highly social and do best in large groups.

Emerald Dwarf Rasboras are a shoaling species. This means the fish will group up and swim together, but they will also go off and do their own thing from time to time.

Author Note: You may see some in-fighting between males. Males will often spar with rivals, which results in nipped fins here and there. In most cases, the fighting will not result in any serious injury. Furthermore, it doesn’t go beyond the species group.

For the most part, these fish are quite active and will swim around exploring the tank throughout the day. They’re very curious creatures, so you will see them zipping through plants and checking out every nook and cranny of the aquarium!

Tank Mates

Beyond fish of the same species, Emerald Dwarf Rasboras can get along with most peaceful freshwater species (and plenty of other types of rasboras). You don’t have to worry about aggression from the Emerald Dwarf Rasboras, but you will need to worry about them becoming food for another.

It’s important to avoid any large or remotely aggressive fish! This species does best with similar-sized fish.

You can also go for tank mates that come from the same region. There are many other species native to Lake Inle in the fish trade.

Here are some good tank mates for the Emerald Dwarf Rasbora:


Emerald Dwarf Rasboras are eager spawners. In pristine conditions, these fish will breed frequently without any intervention. They are egg-scatterers, but they don’t exhibit any parental instincts at all (which makes things a lot easier).

If you want to maximize the survival rates of baby fish, it’s best to breed them in a controlled environment.

Create a separate breeding tank and fill it with well-cycled water. Add spawning mops or leafy plants. Then, add a bonded pair. You can also add a group consisting of two males and multiple females.

Author Note: It’s worth noting that, more individual fish will increase the risks of eggs getting eaten.

At this point you should provide high-protein foods. Spawning should occur relatively quickly. Females will lay about 30 eggs throughout the tank. They’re mildly adhesive, so the eggs may stick on leaves or decor.

Eggs take about 72 hours to hatch. The fish fry will survive on the egg sac for another three to four days before becoming free-swimming. You can then provide infusoria or powdered fish food until they’re ready for baby brine shrimp.            


Emerald Dwarf Rasboras are a wonderful freshwater species that deserve far more attention from the fishkeeping community. Their beauty and ease of care make them a no-brainer!

We hope this guide did an effective job of teaching you the basics of caring for these fish. If you have any other questions that we didn’t answer, don’t hesitate to ask us!

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