Koi Betta Fish Care: Tank Mates, Feeding & Full Details!

Koi betta fish (Betta splendens), a variety of the Siamese fighting fish, are known for their striking appearance that resembles that of the prized multicolored koi.

These fish are not a unique species or a crossbreed between koi and betta fish, but rather a result of selective breeding to bring out their distinct coloration.

Despite their exotic appearance, koi betta fish are not more challenging to care for than regular betta fish. They are hardy, adaptable, and suitable for beginner aquarists.

Aquarium enthusiasts, rejoice! Koi betta fish are a stunning and captivating addition to any fish tank. With their vibrant colors and unique marbled patterns, these fish are sure to be the centerpiece of any aquarium.

In this comprehensive guide, we will dive deep into the world of koi betta fish, covering everything you need to know about their care, habitat, and health. So, let’s dive in and explore the beauty of these remarkable fish.

Quick Facts about Koi Betta Fish

Species Name: Betta splendens
Family: Betta
Care Level: Easy
Temperature: 75 – 85 degrees F
Temperament: Aggressive
Color Form: Black, orange, white
Lifespan: 3 years
Size: 3 inches
Diet: Carnivores
Minimum Tank Size: 10 gallons
Compatibility: Low

Betta 211

Distinctive Features and Types

The main attraction of koi betta fish is their marbled color pattern, which can include a variety of colors such as red, yellow, orange, black, green, and blue.

This marbling gene is responsible for the sharp-edged patches of color and the color-changing nature of these fish throughout their lives. This fascinating trait makes each koi betta fish unique.

There are several types of koi betta fish, including:

  • Galaxy Koi Betta: Characterized by red, black, and white patches, along with iridescent blue and turquoise scales resembling a galaxy.

  • Candy Dragon Koi Betta: Sporting shades of pink, red, purple, and blue.

  • Koi Plakat Betta: Featuring a variety of colors and shorter, rounded fins, similar to other plakat bettas.

Appearance of Koi Betta Fish

Koi Bettas are known for their captivating and vibrant appearance, setting them apart from other members of the Betta splendens species.

These small fish boast flowing, silk-like fins that create a mesmerizing display as they gracefully swim through the water. Koi Bettas exhibit a unique marbling gene that results in a mix of striking colors, often resembling the multicolored patterns of their namesake, the Koi.

These fascinating fish display a wide variety of color combinations, including red, yellow, orange, and black, with some even exhibiting flecks of green and blue.

The patches of color are typically characterized by sharp edges, giving them a distinctive, eye-catching look.

Koi Bettas also possess a color-changing gene that allows their appearance to change throughout their lives, adding to their allure and making each individual truly unique.

Natural Habitat of Koi Betta Fish

Koi Betta Fish, like other members of the Betta splendens species, originate from Southeast Asia. Their natural habitat consists of shallow, slow-moving bodies of water such as rice paddies, stagnant ponds, and small streams.

These environments are often densely vegetated, providing ample hiding spots and shade for the fish.

The water in their natural habitats tends to be warm, with temperatures ranging from 75 to 84 degrees Fahrenheit.

The pH levels can vary between 5.5 and 8.0, with a neutral pH of around 7.0 being ideal. Koi Betta Fish prefer soft water, with a hardness of 4 to 8 dGH.

Origin and Distribution of Koi Betta Fish

The Koi Betta Fish is not a separate species, but rather a color variant of the Betta splendens.

The first Koi Bettas were bred in the 1970s by Orville Gulley, an inmate at Indiana State Prison. Gulley participated in a rehabilitation program that allowed him to breed Betta fish in cleaned-out peanut butter jars.

After attempting to create a different Betta variant, Gulley discovered that the fish he bred had a unique marbling gene.

He sent his marbled Koi Betta Fish to renowned hobbyist Walt Maurus, who then introduced them to the wider Betta breeding community.

Today, Koi Betta are prized among aquarists for their stunning appearance and fetching a premium price in the pet trade.

koi betta size

Growth, Size, and Lifespan of Koi Betta Fish

Koi Betta Fish, like other members of the Betta splendens species, are relatively small in size. Adult Koi Bettas typically measure between 2.5 to 3 inches in length, with Plakat varieties being slightly smaller due to their shorter, rounded fins.

Despite their small stature, these fish have a big presence, thanks to their alluring appearance and active personalities.

In terms of growth, Koi Betta Fish will reach their full size within a few months, given proper care and nutrition.

Feeding them a protein-rich diet, including commercial Betta pellets, live or frozen foods like brine shrimp, and bloodworms, is essential to support their growth and overall health.

Koi Betta have a similar lifespan to other Betta splendens, living for approximately three to five years with proper care.

Providing them with a suitable environment, including a well-maintained tank with stable water parameters and ample hiding spots, is crucial to ensuring they live a long, healthy life.

Regular monitoring of tank conditions, a balanced diet, and timely treatment of any health issues will also contribute to their overall well-being and longevity.

Koi Betta Fish Behavior and Temperament

Koi Betta exhibit a curious and interactive temperament, making them a popular choice among aquarists.

They are known for their inquisitive nature, often engaging with their environment, and displaying a keen interest in their surroundings.

Male Koi Bettas are particularly territorial, which can lead to aggressive behavior when confronted with other males or fish that they perceive as a threat to their territory.

Female Koi Bettas tend to be more social, but they can also display assertiveness when establishing dominance within a group.

Tank Setup: Creating an Ideal Environment for Koi Betta Fish

To ensure the health and happiness of your Koi Betta Fish, it is crucial to provide them with an appropriate tank setup that closely mimics their natural habitat.

Here are some key aspects to consider:

Tank Size

For a single Koi Betta, a minimum tank size of 5 gallons is recommended. If you plan to house more fish or introduce tank mates, a larger tank will be necessary to accommodate the increased bioload and provide enough space for all occupants.


Choose a soft, fine-grained substrate like sand or smooth gravel to replicate the natural environment of Koi Betta. This will also prevent potential injuries to their delicate fins and allow for the growth of live plants.

Decorations and Hiding Spots

Incorporate plenty of live plants, rocks, and driftwood to create hiding spots and shaded areas for your Koi Betta Fish. This mimics their natural habitat and provides them with a sense of security. Popular plant choices include Java Fern, Anubias, and Amazon Sword.

Water Parameters

Maintain stable water parameters, with a temperature between 75-84°F, a pH of 5.5-8.0, and a water hardness of 4-8 dGH. Consistency is crucial, as sudden changes in water parameters can cause stress and harm your fish.

Filtration and Aeration

Invest in a high-quality, gentle filter to remove impurities and maintain water quality. Koi Betta prefer slow-moving water, so avoid strong currents that may stress them. A sponge filter is an excellent option, as it provides gentle filtration without creating a powerful current.


Koi Betta Fish do not have specific lighting requirements, but a standard aquarium light is sufficient. Mimic their natural environment by providing a consistent day-night cycle, with around 8-10 hours of light per day.

Tank Mates

Due to their territorial nature, male Koi Betta Fish should be housed alone or with compatible, non-aggressive tank mates. Suitable companions include Corydoras catfish, small Rasboras, and peaceful Tetras. Avoid housing with fin-nippers or brightly-colored species that may trigger aggression.


Feed your Koi Betta Fish a varied diet of high-quality commercial Betta pellets, live or frozen foods like brine shrimp and bloodworms, and the occasional treat of vegetable matter. This balanced diet will support their growth, coloration, and overall health.


Regular tank maintenance is essential for the well-being of your Koi Betta. Perform weekly water changes of 25-30% to maintain water quality and remove waste. Monitor water parameters regularly and adjust as needed. Clean the substrate and remove any decaying plant matter to prevent the buildup of harmful bacteria or algae.

Koi Betta Fish Galaxy Female Male Care Guide

Tank Maintenance of Koi Betta Fish

Proper tank maintenance is crucial for the well-being of your Koi Betta. A clean and stable environment promotes their health and longevity.

Here’s a detailed breakdown of essential maintenance tasks:

Regular Water Changes

Performing regular water changes is vital for maintaining optimal water quality. Replace 25-30% of the tank water with fresh, dechlorinated water every week.

This helps remove waste, uneaten food, and any chemicals that can accumulate over time. It is essential to ensure the new water matches the temperature, pH, and hardness of the tank water to avoid stressing your fish.

Cleaning the Tank and Decorations

Clean the tank walls, decorations, and substrate to remove algae, dirt, and debris. Use a soft, non-abrasive sponge or brush to clean the glass, and a gravel vacuum to clean the substrate without removing it from the tank.

Remove and rinse decorations in a separate container with dechlorinated water to avoid introducing harmful substances into the tank.

Filter Maintenance

Maintain the filter by cleaning or replacing the filter media as per the manufacturer’s guidelines.

Be sure to clean or replace only a portion of the filter media at a time, as completely replacing it can disrupt the beneficial bacteria needed for proper biological filtration.

Rinse the filter media in the tank water, not tap water, to preserve the beneficial bacteria.

Monitor Fish Health

Regularly observe your Koi Betta for signs of stress, illness, or injury. Familiarize yourself with their typical behavior and appearance to quickly identify any changes that may indicate a problem.

If you notice signs of illness, such as lethargy, loss of appetite, or visible lesions, take appropriate action to address the issue and consult a veterinarian if necessary.

Acclimating Koi Betta Fish

Proper acclimation is crucial for ensuring the health and well-being of your Koi Betta Fish as they adjust to their new environment.

Here’s a step-by-step guide to acclimating your fish:

  1. Floating the Bag: Float the sealed bag containing your Koi Betta in the tank for 15-20 minutes to equalize the temperature. This minimizes temperature shock, which can be harmful to your fish.

  2. Adding Tank Water: After the temperature has equalized, open the bag and slowly add small amounts of tank water to the bag every 5 minutes for 30-45 minutes. This allows your fish to gradually adjust to the water chemistry of their new home.

  3. Netting and Releasing: Once the acclimation process is complete, use a soft net to gently scoop your Koi Betta from the bag and release them into their new tank. Discard the water in the bag, as it may contain waste and other contaminants.

  4. Monitoring: Keep a close eye on your Koi Betta for the first few days, observing their behavior and ensuring they are adapting well to their new environment. Monitor the water parameters to confirm they remain stable and within the appropriate range.

Koi Betta Fish Diet and Feeding

Koi Betta Fish are carnivorous and thrive on a diet rich in protein. Feeding them a varied diet will help ensure they receive all the necessary nutrients for their growth and overall health.

Here’s a detailed guide on their diet and feeding habits:

  1. Pellets and Flakes: High-quality Betta pellets or flakes should be the staple of their diet. Choose products specifically designed for Betta fish, as they contain the right balance of protein, vitamins, and minerals.

  2. Frozen and Live Foods: Supplement the pellets or flakes with frozen or live foods, such as brine shrimp, daphnia, bloodworms, and mosquito larvae. These foods provide essential nutrients and help stimulate their natural hunting instincts.

  3. Feeding Frequency: Feed your Koi Betta Fish once or twice a day, offering them only as much food as they can consume within 1-2 minutes. Overfeeding can lead to obesity, poor water quality, and other health issues.

  4. Fasting: Consider fasting your fish for one day per week to help clear their digestive system and prevent constipation.

Koi Betta Fish Tank Mates

While Koi Betta Fish can be aggressive, especially towards other Betta fish, they can coexist with some peaceful, non-aggressive tank mates.

Here are some suitable tank mates for your Koi Betta Fish:

  1. Small, Peaceful Fish: Species like neon tetras, ember tetras, and harlequin rasboras are suitable tank mates, as they are small, peaceful, and fast enough to avoid the Betta’s aggression.

  2. Bottom-Dwellers: Bottom-dwelling fish, such as Corydoras catfish and Kuhli loaches, make good tank mates because they occupy a different area of the tank and are less likely to compete for resources.

  3. Invertebrates: Shrimp and snails can be suitable tank mates for Koi Betta. However, individual Bettas may be more aggressive towards invertebrates, so it’s important to monitor their behavior and separate them if necessary.

male galaxy koi betta nemo Ron Kuenitz Shutterstock

Breeding Koi Betta Fish

Breeding Koi Betta Fish can be a rewarding experience, but it requires careful preparation and attention to detail.

Here’s a step-by-step guide to breeding Koi Betta Fish:

  1. Separate Breeding Tank: Set up a separate 5-10 gallon breeding tank with shallow water (about 6 inches), a sponge filter, and a heater to maintain a stable temperature between 78-82°F.

  2. Feeding and Conditioning: Condition the male and female Koi Betta Fish with high-quality food and live or frozen foods for 1-2 weeks before introducing them to the breeding tank.

  3. Bubble Nest: Introduce the male to the breeding tank first and provide him with floating plants or a cup to encourage bubble nest building.

  4. Introducing the Female: Once the male has built a bubble nest, introduce the female to the tank, using a divider to separate them. Monitor their behavior, and if the male does not show aggression, remove the divider.

  5. Spawning: The male will court the female by wrapping himself around her and squeezing the eggs out, fertilizing them in the process. He will then place the eggs in the bubble nest.

  6. Post-Spawning Care: Remove the female from the tank after spawning, as the male will become aggressive to protect the nest. The male will tend to the nest for the next 24-48 hours, during which the eggs will hatch.

Raising Koi Betta Fry

  1. Raising Fry: Once the fry become free-swimming (usually about 3-4 days after hatching), remove the male from the tank. At this stage, the fry will need to be fed multiple times a day with live foods suitable for their size, such as infusoria, baby brine shrimp, or micro worms.

  2. Frequent Water Changes: Perform frequent, small water changes to maintain optimal water quality and support the fry’s growth. Be sure to use a gentle siphon to avoid harming the delicate fry.

  3. Growth and Development: As the fry grow, gradually increase the water level in the tank and transition them to larger foods like daphnia, bloodworms, and crushed pellets or flakes. It may take about 8-12 weeks for the fry to reach a size where they can be safely introduced to a community tank.

  4. Sexing and Separation: Around 6-8 weeks of age, you may start noticing the differences between male and female fry. As the males begin to display their characteristic aggression, separate them into individual tanks or containers to prevent fighting and injuries.

  5. Continued Care: Continue to provide your Koi Betta Fish with a high-quality diet, proper water conditions, and a suitable environment as they mature. With proper care, Koi Betta Fish can live up to 3-5 years, and their stunning colors and patterns will only continue to develop and impress.

Breeding Koi Betta Fish can be a challenging yet gratifying endeavor.

By following the steps outlined above and dedicating time and attention to their care, you can successfully raise a new generation of these beautiful fish.

Remember to be patient and attentive to their needs, and you’ll be rewarded with a thriving group of Koi Betta Fish.

Signs of Stress in Koi Betta Fish

  1. Loss of Color: A stressed Koi Betta Fish may lose its vibrant colors or become duller in appearance.

  2. Lethargy: A stressed fish may become inactive, staying near the bottom of the tank or hiding in decorations.

  3. Loss of Appetite: If your Koi Betta Fish is not eating well, it could be a sign of stress or an underlying health issue.

  4. Rapid Breathing: Fast or labored breathing may indicate that your fish is stressed or experiencing poor water quality.

  5. Clamped Fins: When stressed, Koi Betta Fish may clamp their fins close to their body, rather than extending them fully.

Common Health Issues and Treatments for Koi Betta Fish

  1. Fin Rot: Fin rot is a bacterial infection that causes the fins to become ragged and discolored. Treatment includes improving water quality, adding aquarium salt, and using a broad-spectrum antibiotic.

  2. Ich: Ich is a parasitic infection that presents as white spots on the fish’s body. To treat ich, raise the tank temperature gradually to 86°F and add aquarium salt or use over-the-counter ich medications.

  3. Swim Bladder Disorder: This condition causes difficulty in swimming and buoyancy issues. Fasting the fish for a couple of days, followed by feeding them shelled peas, can alleviate the problem. Maintain good water quality to prevent the disorder.

  4. Popeye: Popeye is an infection that causes the eyes to bulge. Antibiotics, maintaining optimal water quality, and lowering stress levels can help treat this condition.

Additional Tips for a Healthy Aquarium

Cycle Your Tank:
Perform a fishless cycle before introducing fish to establish a stable nitrogen cycle and avoid harmful ammonia and nitrite spikes.

Test Water Parameters Regularly:
Monitor your tank’s water parameters to ensure optimal conditions for your Koi Betta Fish.

Avoid Overfeeding:
Feed your fish only what they can consume within a couple of minutes to prevent leftover food from fouling the water.

Quarantine New Fish:
Quarantine new fish for at least two weeks to prevent the introduction of diseases or parasites into your main tank.

Should You Get a Koi Betta Fish for Your Aquarium?

Koi Betta Fish are beautiful and unique pets that can be a wonderful addition to your aquarium. If you are prepared to provide the proper environment, diet, and care for these fish, they can thrive in your home.

Be aware of their specific needs, such as suitable tank mates and water parameters. They need dedicated time to regular maintenance to ensure a healthy and vibrant aquarium.

If you feel confident in your ability to care for Koi Betta and appreciate their stunning appearance, they can be an excellent choice for your aquarium.

koi betta fish male Ron Kuenitz shutterstock

Conservation Status

Koi Betta Fish are a selectively bred variant of the common Betta fish (Betta splendens), which is classified as “Vulnerable” on the IUCN Red List.

Their natural habitat in Southeast Asia has been threatened by factors such as pollution, deforestation, and over-collection for the pet trade.

However, Koi Bettas are primarily bred in captivity, reducing pressure on wild populations.

Availability & Pricing

Koi Betta Fish are widely available in the pet trade due to their popularity and captive breeding.

They can be found at local pet stores, specialty fish stores, and online retailers. Pricing varies depending on factors such as coloration, finnage, and quality.

A basic Koi Betta may cost between $10 and $20, while premium specimens with intricate patterns and vibrant colors can cost upwards of $50 or more.

Frequently Asked Questions About Koi Betta Fish

Do Koi Betta Fish need a heater?
Yes, Koi Bettas require a stable water temperature between 76°F and 82°F. A heater and thermometer are essential to maintain the appropriate temperature in the tank.

Can Koi Betta Fish live with other fish?
Some Koi Betta can coexist peacefully with other fish species. However, care must be taken to select compatible tank mates to avoid aggressive behavior or overcrowding.

How often should I feed my Koi Betta Fish?
Feed your Koi Betta a high-quality diet once or twice daily, offering only what they can consume within a few minutes.

How long do Koi Betta Fish live?
With proper care, Koi Betta can live for an average of 3 to 5 years.


Koi Betta are captivating and visually stunning aquarium pets. They require specific care, including appropriate water parameters, suitable tank mates, and a balanced diet to thrive.

By understanding their unique needs and dedicating time to regular maintenance, you can provide a healthy environment for your Koi Betta.

Given their accessibility and cost-effectiveness, Koi Betta have become a favorite among aquarium enthusiasts. Nevertheless, it is crucial to be thoroughly prepared for their care in order to guarantee a flourishing and lively aquarium environment.