Betta Macrostoma: Guide to Keeping the Brunei Beauty

betta macrostoma
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For advanced fishkeepers or even those who are new to the whole idea, the breed Betta macrostoma is among those rare and exotic fishes that one would be lucky to own.

If you’re like me, someone who wishes to own a pair soon, there are certain things that you’ll have to know and understand to ensure the safekeeping of your Brunei Beauty – the holy grail of bettas.

What is a Betta Macrostoma?

The Betta Macrostoma is a rare species of Betta and is part of the unimaculata complex. If you’re interested, you can read more about Betta complexes here.

As they are considered rare, these are easily the most expensive Bettas in the aquarium trade.

They are not too flashy in their looks compared to the domestic Betta splendens. And they’re generally calmer to keep compared to different Betta varieties. 

But if you have more than 1 male in an aquarium, light squabbles for territory might occur, as you can see in this video.

These varieties are also excellent jumpers, so watch out for your tank!

Common names for Betta Macrostoma

Betta Macrostoma is the scientific name for this Betta variety. It is also known by many other common names such as Spotfin Betta, Brunei Beauty, Orangecheek Betta, and Peacock Betta. 

Where can the Betta Macrostoma be found?

Betta macrostoma is native to Borneo, and we can find it in Brunei Darussalam’s waters and the Northern tip of Sarawak in Malaysia.

But if you live far from these places (like me), you can get in contact with reputed fisheries that either breed or import the variety into your area.

Keep in mind that these bettas are endangered species, and capturing wild-bred Betta Macrostoma in Brunei is illegal. The safe option is to opt for captive-bred bettas.

Localities of Betta Macrostoma

The 2 main localities of the Betta macrostoma are “Brunei” and “Marudi” – both indicating its Brunei and Sarawak origins.

Betta Macrostoma habitat

The wild habitat of Betta macrostoma includes dense vegetation, jungle cover, and flowing streams. These sources’ water is can be shallow, 1-2 ft deep, and may often have a current.

There have been reports of them being collected in still water pools as well. Regardless, their water is usually stained brown from decaying organic matter and have clayey or gravel substrates.

How to take care of Betta Macrostoma

The IUCN (International Union for Conservation of Nature) has marked Betta macrostoma as a Vulnerable (Threatened) species, making it difficult to find and keep. 

This also makes it a big investment financially to keep. 

Betta macrostoma is highly vulnerable to water chemistry and temperature, and too many changes could cause health problems. So always make sure that its water is clean and kept in optimal temperatures.

The usage of filters is almost necessary for water flow and housing essential beneficial bacteria required. Make sure to cycle it properly to remove any harmful chemicals present in the water. 

Through my own research, I’ve read that the thriving of Betta macrostoma can greatly depend on how well the aquarium has been cycled. 

Many keepers prefer to change the water partially (20-25%) every week to keep it fresh and clean. 

Recommended tank size for Betta Macrostoma

The bare minimum for a pair of Betta macrostoma is a 60 x 30cm (2 x 1ft) aquarium. However, if you’re planning to breed them as well, it’s best to get a bigger aquarium measuring 80 x 30 cm at its base or larger.

Generally, Betta macrostoma is best kept in large aquariums – primarily due to them being sensitive to water conditions. 

Large water volumes keep the water chemistry stable that will prevent any diseases or problems with your Betta.

The preferred aquarium layout for Betta Macrostoma

A well-planted aquarium that has lots of hiding spaces is ideal for Betta macrostoma. The substrate can be either soil or gravel, depending on the plants you’re keeping them with.

The addition of good caves, leaf litter, plants, and a dark background is also ideal. The dark background helps make them feel secure and aids in developing more intense colouration from this species.

The addition of leaf litter will release tannins that soften the water while emulating its natural habitat.

Decaying leaf litter also promotes the growth of microbes that act as a secondary food source for fries.

If you’re planning to breed, then go for a bare bottom, as this is often the best pick for breeding Bettas.

Recommended water conditions for Betta Macrostoma

The water temperature should be between 20-25C (68-77 F) and maintain its pH at 4.0-5.7. The hardness of the water should be roughly around 0-90 ppm.

Not only these are the ideal setups to keep the Betta healthy, but it is also almost compulsory to replicate these water conditions. Betta macrostoma keepers and breeders find that any deviation will cause problems with health and even breeding. 

Some even say that if the conditions aren’t right, the Betta macrostoma will swallow the eggs after breeding.

These are definitely one of the most sensitive and difficult Bettas to take care of.

If you’re in the tropics, a chiller should help you achieve these temperatures.

What can you keep with Betta macrostoma?

Although the males can be dominant, you can safely keep these breeds in pairs and even groups if you like. 

But keep in mind that you should not keep it with other fishes as these are one of the most sensitive Bettas.

In their natural habitat, only the Rasbora tubbi and Machrobrachium sp. shrimp is found. The latter suspected to be a large part of its diet.

What to feed Betta Macrostoma?

The Betta macrostoma is relatively easy to feed as it can consume a good variety of feed. 

Live or frozen food can be fed, but they are fussy when trying to feed dried food. Many prefer to feed brine shrimp, krill, daphnia, tubifex, mysis shrimps, or bloodworms.

Plus, if you maintain the aquarium with suitable plants and leaf litter, the microbes produced from their decomposition can be used as a secondary food source. Just make sure to keep it clean and maintained.

Sexing Betta Macrostoma

Once fully mature, Betta Macrostoma is easy to differentiate between its sexes. 

The males always have brighter and more intense colourations compared to females. Males can come in colours like black, vibrant reds, or oranges.

To identify a female, you can look for a lateral band on its body which males will not have.

Here’s a reference of macrostoma male and female

Breeding Betta Macrostoma

The breeding process of Betta Macrostoma can be fascinating but also tricky and tedious for many breeders. They are mouthbrooders which means that the male carries the eggs from the female to incubate them.

These are the things you can look out for during their breeding process.

  • Courtship: Around 6 to 7 months of age, males can start displaying their courtship. You’ll notice them bending their body in a curve and having erect fins. This is their way of showing off so that the female will choose it over its competitors. 

The females may stay dormant for one or two days when the male performs his courtship. But after this, her behaviour will change and also develop two black lines horizontally on her body. At this stage, it’s best to leave the pair alone. They perform their courtship displays turn by turn.

  • Spawning embraces and transfer of eggs: During this process, the female releases the eggs, which the male has to accumulate in his anal fin and fertilise it by releasing milt.

While embracing, both macrostoma can be stunned for some moments.

The female then collects the eggs, and the male may or may not help along.

Once the eggs are all collected, the male focuses on the female, and she spits the eggs towards him, and he catches it into his mouth. For breeding enthusiasts, this is one of the most exciting sights to witness.

Here you can see a visual of the transferring process:

  • Buccal Incubation and Fry: This incubation period can be the determining factor of the whole process. Its success depends on the male’s ability to keep the eggs properly in his mouth. 

The most common reasons why Betta macrostoma fail to hold to term are 

  • Accidental spooks that scared the male. If you haven’t seen your male, assume that he is brooding and don’t go digging in the tank looking for him.
  • pH levels not low enough. Adjust your pH levels slowly to the level that they’re comfortable with. It’s usually below 5.0.
  • Water temperature too warm. You might need to use a chiller to decrease the temperature.
  • Food. The food you’re feeding the female is too tempting for him.
  • Inexperience. He’ll just have to keep trying.

But once it successfully incubates it (which typically takes 17 to 20 days), be ready to take care of both the bettas. Remove the female about 5 days after they spawn. Start feeding her again and continue not feeding the male.

Once the male releases the fry successfully, they will be fully formed and active. You can choose to keep them in a separate tank, but most breeders find that keeping the parents with them is fine.

Apart from this natural process, if it gets too challenging to breed Betta macrostoma (often due to bad male Bettas), you can also try artificial incubation. This is done by stripping the male and keeping the eggs in a safe incubation container.

Here are some reference videos to understand this process.

Male macrostoma stripping:

Artificial Incubation:

Average lengths of Betta Macrostoma

Newly hatched fry of macrostoma can be 0.508 to 0.9906 cm long, and by six months, they can grow up to 11 cm (4.3 inches).

Lifespan of Betta Macrostoma

The lifespan of any fish species can depend a lot on the level of care and maintenance one gives; the same goes for the Betta macrostoma.

But on average, it’s reported that these varieties can live for 3 to 5 years, but some also claim to have it for more than 8 years.

Similar Species

Visually, there are no other Bettas with the same colouration, patterns, and fins as the male Betta macrostoma. However, females from the unimaculata complex have similarities with each other that might confuse beginners. 

If unsure, ask a reputable breeder or try reading online sources to identify them correctly.


Betta Macrostoma is a rare and exotic variety of the Betta species. Often called the holy grail of bettas, these bettas are both fun yet tedious (and expensive) to own.

Heck, where I’m from, they’re easily $200-$300 a pair. If you’re in Europe or the Americas, I can imagine a heftier price tag for these beauties. Not to mention the weekly maintenance if you don’t already have soft acidic water. If you’re in the tropics like me, a chiller will cost you a bomb!

Since it’s an endangered species, it can be hard to get, but it’s a worthy goal to have for any fish keeper to successfully keep and breed this species. 

Just make sure to keep it away from other fishes, keep it in optimal environmental conditions, and tend to its needs regularly. Once you’re able to understand all that, you’re good to go as a Betta macrostoma parent.

Have any images, videos, or information to contribute? Do reach out to me, and I’ll share them in this post!

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