Spotfin Betta Macrostoma – Profile & Facts

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If you are a passionate Betta fish lover, you certainly know there are many varieties of these spectacular creatures available. One of the rarest is the Spotfin Betta Macrostoma, which is called like that thanks to its naturally enlarged mouth (and macrostoma literally translates to big mouth).

As this is a still quite unavailable pet among most aquatic lovers, we are sharing its full profile and fun facts.

This peculiar fish originates from the Borneo island, where it usually populates very shallow pools of slow-moving water along streams and rivers. It was first discovered many years ago, but this fish is so rare that people thought it was extinct for many years (more than 50!).

Later, in 1981, the Spotfin Betta has been re-discovered and found alive into a waterfall in Brunei Darussalam. This brought to a massive interest among many exotic fish breeders and enthusiasts, who simply wanted to save the species by reproducing it in captivity.

They succeeded, at least a bit, even after the Sultan of Brunei prohibited exporting them from their natural habitats.

Also Read: Some Bettas Can Cost a Lot of Money


Betta Macrostoma is often referred to as the Brunei beauty, and this should come as no surprise to anyone. In fact, they are one of the most beautiful fish in the world.

The Brunei beauty usually reaches a full size of between 3.5 and 4.5 inches. Surprisingly, it can live anywhere from 3 to up to 10 years in captivity, as long as proper care is provided.

The Spotfin Betta is a mouthbrooder so it, therefore, has a larger mouth. It usually features a longer body trunk with short and round fins. However, its dorsal fin is what makes this Betta so special.

Indeed, this usually features a spectacular large black and red eyespot. When added to its light red or brownish body coloration, along with a black face, the Brunei beauty will rarely leave any human unamazed.

Behavior & Personality

When compared to most other Betta varieties, the Spotfins are usually slightly less aggressive. That is why they can often function surprisingly well when kept in pairs or even in smaller groups. However, they do not make the friendliest tank mates to other fish.

When kept in pairs, they will mostly choose to breed naturally. And observing how the male wraps around the female body while spawning is simply magnificent. Sometimes, spawning can last for even 4 hours.

As already mentioned earlier, Betta Macrostomas are paternal mouthbrooders, which means that the male fish will hold the eggs in its mouth for several weeks, until the fries are hatched. If being stressed, however, fathers can sometimes decide to swallow the eggs.

Care & Requirements

Before we start here, it is necessary to make a couple of things clear first. The Burnei beauty is an extremely rare fish and, even if some breeders managed to save them from extinction and to re-produce them into captivity, there are still not many around and the species is endangered.

That is why, as opposed to many other Betta types which are great choices for inexperienced aquarium owners, this one needs to be an exception. So, please do not plan of getting yourself into adopt such special fish unless you have some experience.

These exotic fish are happiest when kept in pairs. If you are able to find a female and a male, a 40-gallon tank is recommendable.

With them being slightly larger from the rest of the Betta family members, enough space is essential. Especially if you are planning on allowing them to breed. Also, always go with lidded tanks, as they make amazing jumpers.

Next, another super-important necessity is providing them with an extremely planted environment. This is essential as it will make them feel most safe and comfortable and will at the same time provide them with enough hiding places and resting spots.

Some owners like to setup gravel or sandy substrates, but they seem to prefer bare bottom tanks, with just some leaf litter around.

Spotfin Bettas are not that picky when it comes to water conditions and will accept very well any temperature between 70- and 80-degrees Fahrenheit and a pH around 6.

However, what they will not accept is any oscillation of such water requirements. Once the temperature and chemistry levels are set, it is vitally important to keep them stable at all times.

Food & Diet

Betta Macrostomas are predatory omnivores. They feed with commercial pellets or flakes, as well as frequent live or frozen meaty treats, such as brine shrimp or bloodworms.

They should be fed only once or twice per day, and they are just as sensitive to overfeeding as any other Betta.

Health Problems

The biggest health problems among these fish are unfortunately caused by water parameter changes or improper diet. The most often are surely related to fungal infections, skin and gill flukes, costia, fin rot, and cottonmouth disease.

All of them can be treated if spotted at an early stage, but all of them can also be prevented with the help of proper maintenance.


  1. Betta Macrostomas are listed as “vulnerable” on the IUCN Red List of Threatened Species.
  2. They make one of the most expensive Betta fish in the world.
  3. Betta Macrostoma is actually part of the Betta Unimaculata complex.
  4. Some Spotfin Bettas can grow big enough to be occasionally fed with earthworms.
  5. Males and females that live in groups will always squabble until they establish a hierarchy.

Wrapping Up

The Burnei beauty does not only feature a highly intriguing name, but it also makes one of the most wanted exotic fish around the world.

So, if you want to get a pair of spotfin bettas, be sure you have enough experience to keep them alive.

There are plenty of other Bettas around but let us leave the endangered species to those who will offer them a more stable home.

Author Image Fabian
I’m Fabian, aquarium fish breeder and founder of this website. I’ve been keeping fish, since I was a kid. On this blog, I share a lot of information about the aquarium hobby and various fish species that I like. Please leave a comment if you have any question.

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