Betta Macrostoma (Spotfin Betta)

There are several species of fish that are unusual and exotic. These fish are very hard to find and even harder to maintain as aquarium fish. However, if you can keep these fish in the right circumstances, your tank will be the center of attention.

When it comes to rare and beautiful fish kinds, the Betta Macrostoma is unquestionably one of the most unusual and exotic. Most fish keepers regard it as the holy grail of the betta family.

So what are its characteristics that make it unique? And how can you properly care for this fish? Read on to know all about Betta Macrostoma and make yourself a great fish parent.

Betta macrostoma overview
AppearanceOrange hue, large mouth, smaller fins
Temperament Peaceful and less aggressive
Incubation method Mouthbrooders

Get to know Betta Macrostoma

Small orange fish laying on rocks at bottom of fish tank.
Spotfin betta

The Betta Macrostoma, also known as the spotfin betta, is among the rarest and most costly types of Betta fish available. It has a distinct look and personality from other betta species like Betta Splendens (the types of betta fish you’ll typically find at your local pet store). This fish has a long body and short dorsal fin. Spotfin betta fish also lack the flowy tails that most people associate with a typical betta fish.

Furthermore, because they do not create bubble nests (and are mouthbrooders) their faces are broader than other Bettas. They are also a little more laid-back and than their Betta counterparts that are known to be vigorous fishes. Afterall, Betta Splendens have earned the nickname “Siamese fighting fish”.

Wild Betta Macrostoma are hard to find as their natural habitat is degrading, therefore, most domesticated Macrostoma are kept and bred in captivity.

Since this species of peaceful fish is so uncommon and such a vulnerable species, it’s typically advised that only experienced aquarists keep them.

What does a Betta Macrostoma look like?

Brunei beauty is a name given to Betta Macrostoma for a reason. Its eye-catching brilliant orange hue makes it instantly recognizable. It differs from well-known species like Betta Splendens in that its fins are more subtle and lack the assertive fins seen in Betta Splendens.

Betta Macrostoma have a large mouth, which is one of the primary things you notice while looking at them. Its scientific term originates from macro (large) and stoma (mouth).

Small orange fish.

Due to sexual dimorphism, males tend to have large mouth and broader head shape for breeding and, because of these traits, can handle larger prey. When a male flares, he will expand his lips as wide as possible to surprise the opponent.

The Betta Macrostoma’s fins have black patterns. There is one dark vertical line on the cheek scaling, and the mouth is entirely black. 

Natural habitat

Betta Macrostoma is a Borneo native that you may find in Brunei Darussalam’s seas and Sarawak’s northern edge. However, if you live away from these locations, you may contact reputable businesses that raise or import the species into your region.

Remember that these Bettas are critically threatened species, and it is punishable in Brunei to capture wild population of Betta Macrostoma. Choosing captive-bred Bettas is the safest choice if you’re looking for peaceful species and don’t want wild caught specimens.

“Brunei” and “Marudi” are the two primary locales of the Betta Macrostoma, signifying its Brunei and Sarawak origins, respectively. Moreover, the only sympatric fish species recorded is Rasbora Tubbi.

Betta Macrostoma’s natural environment includes thick foliage, jungle cover, and running streams. The water in these sites might be shallow (one to two feet deep) and current. You can also see Brunei fish in still water pools or rainforest waterfalls. 

Their water is frequently tinted dark from rotting organic materials, and their substrates are clayey or sandy.

How to take care of a Betta Macrostoma

Larger Betta Macrostoma tanks are ideal for this fish. A couple of fish can be suitable for a 20-gallon aquarium, while clusters are generally kept in a 40-gallon fish tank. Since these fish are superb jumpers, a tight-fitting cover with no gaps is necessary.

These Bettas will thrive in a landscaped tank setup with lots of hiding places. A bare bottom is a favorable option in many cases, especially for breeding Betta Macrostoma couples. Dried leaf litter may give your aquarium a more natural appearance while maintaining consistent, healthy water conditions.

When it comes to water conditions, Betta Macrostoma can survive a broad range of pH values; however, a pH of at least 6.0 is good. A water temp between 70 and 85 degrees is preferable.

One important note is to ensure you have slow moving water in the tank. Don’t use filters that create currents, as spotfin betta require water flow that mimics the shallow pools of water where they naturally live.

An essential thing to understand about these fish is that they are sensitive to changes in water conditions or temperature. Any change in the water’s chemical or temperature may create health concerns, so it’s critical to keep it clean in such a way that it maintains consistent chemistry and temperature.

Partial water changes may assist in maintaining the water clean without affecting the chemistry. If you don’t have a filter, change 30% to 50% of the water weekly. If you have a filter, you only need to change 20% weekly. Sponge filters can promote the development of good bacteria without causing an excessive water flow. You should also complete full tank cleans every 6-8 months.

Before introducing any Betta Macrostoma to your aquarium, ensure it’s wholly cycled to ensure there are no dangerous nitrites, or ammonia.

What to feed a Betta Macrostoma

Betta Macrostoma are not picky eaters. To receive all the vitamins and nutrients they need, the diet must include Betta granules, frozen foods like bloodworms, or baby brine shrimp. They also like to eat smaller fish which you can include in their diet if you are able to buy some at your local pet store.

You must feed them a natural diet or frozen food once or twice a day and only the amount of nutrition they can easily consume within a few minutes.

Tips to keep your Betta Macrostoma healthy

When designing your aquarium, consider adding driftwood stems and branches to create shady areas where your betta can relax. You can also consider adding floating plants to provide a shady environment for your fish.

If you can’t obtain driftwood, a well-dried and bark-free common birch or oak will suffice. You may provide additional shelter by using clay flower pots or sections of pipe.

Try inserting dried fallen leaves, such as beech, oak, or Ketapang almond leaves. It may enhance the natural feel while providing extra shelter for the fish and encouraging the establishment of microbial colonies as the leaves decompose. 

These may be a good source of secondary food for fry, and the antioxidants and other compounds generated by leaf litter are also helpful.

This species, like other bettas, seems to thrive in low or fairly dim lighting. Aquatic plant types that can flourish in such circumstances, such as Microsorum Pteropus, Barbieri, or rooted Cryptocoryne, are good choices. You can also add a few sections of floating vegetation or clay plant pots. 

Filtration need not be influential; an air-powered microfiber filter set to spin over gradually would suffice. Keep the aquarium well-covered, and don’t keep too many betta fish in one tank.

Breeding of Betta Macrostoma

Betta Macrostoma’s breeding process is exciting, but it can also be difficult and time-consuming for many keepers. They are mouthbrooders, meaning the Betta Macrostoma males bear the female’s eggs and incubates them.

These are the stages to keep an eye out for throughout their breeding process:


The intensely colored male approaches the female for courting at six to seven months. You’ll see that they have vertical fins and bend their bodies in a curve. This is their manner of displaying their superiority over their competition to get females to pick them.

When the male excessively conducts his wooing, the female Betta Macrostoma may become inactive for one or two days. Her behavior will alter after that, and two black lines will appear across her body. It’s better to leave the duo alone at this point. Turn by turn, they will put on their wooing shows in the breeding tank.

Spawning mechanism and egg exchange

The female delivers all the eggs, which the male must collect in his anterior fin and fertilize by producing milt throughout the spawning process. Both Macrostoma go still for a few minutes when mating. After that, the female gathers the eggs, and the male fish may or may not assist her.

Once gathered by the female, the male turns his attention to the female. She then spits the eggs at him and the male will collect the fertilized eggs in his mouth. It’s a fascinating sight to see!

Buccal fry and incubation

This phase of incubation might be the deciding element in the whole process. Its success is contingent on the male’s ability to hold all the eggs in his mouth correctly. Betta Macrostoma fails to hold to the term for various reasons. Some points you should remember are:

  • Unplanned surprises: If you haven’t seen your male in a while, presume he’s brooding, and don’t go rummaging in the breeding tank.
  • Uncomfortable pH levels: Alter your pH levels gradually until they’re at a reasonable level, around 6-7 pH.
  • Inhabitable water: Check the water temperature regularly. The adult pair will not mate in warm water. Hence, you can use a water chiller to cool down the temperature.

However, after successfully incubating (which usually takes 17 to 20 nights), breeders must care for both Bettas. Five days after they spawn, remove the female Betta.

The fry will be wholly developed and active after the male properly releases them. If you like, you may keep them in a different tank, but most keepers find that keeping males with the larvae is ok.

Fry care

Nutrition is essential for the fry’s healthy development and general health. Microworms, vinegar minnows, grindal nematodes, white insects, baby shrimp, and daphnia are also acceptable foods for Betta Macrostoma fry.

Betta Macrostoma fry is more vulnerable to water parameters than an adult fish. As a result, it’s critical to frequently keep an eye on the water quality and temperature. 

Furthermore, fry produces a growth-inhibiting hormone into the environment. Other fry’s development slows down, mainly if the hormone accumulates up in the water. As a result, it is essential to replace the water frequently. A daily water change of 10% is best.

The fry will develop quickly if they are appropriately cared for. They will show their colors at the age of two months. The colors and markings will eventually grow more pronounced, allowing male and female to be distinguished. 

The males will ultimately begin to act aggressively against one another and you must separate them or relocate to a bigger tank at this time.

Tankmates For Macrostoma Betta

Breeders should carefully choose Betta Macrostoma tank mates, and a species-only tank is a good option. In a 20-30 gallon tank, a pair of Betta Macrostoma is excellent. You may also maintain them in groups since they aren’t incredibly aggressive fish.

While males may be violent against one other, it is feasible to keep them together if the tank is big enough. Each male should create his territory if there is adequate area. Male Betta Macrostoma is less hostile than male Betta Splendens, which are very aggressive fish.

While Betta Macrostoma is generally a calm fish, you must keep them in a separate tank. They have large jaws and will consume smaller fish. Keeping them alongside bigger fish may stress or injure them, and you must avoid it, especially given how uncommon they are.

Even if the temperaments of the fish are compatible, the tank needs might be different. A species-only tank is typically the most crucial choice for providing the most delicate habitat for these fish.

Common diseases and health problems

Betta Macrostoma may develop a fungal infection, which, if left untreated, may be deadly to the fish. Bacterial infections are quite prevalent in this species. You should begin medication or the correct therapy as soon as you see the first indicators of a health condition.

The parasitic illness known as skin and gill infection is another primary concern among Macrostoma. This condition also jeopardizes their health. Going into further depth, the following are Betta Macrostoma’s health issues and diseases:

Cotton mouth illness

Cottonmouth illness might be mistaken for a fungal infection at first glance. However, Flavobacterium Branchiophilum is the cause of this condition, which is a bacterial infection. Combine sea salt with methylene blue in water to cure it, or use Terramycin and Aureomycin.

Cotton Mouth causes the following symptoms:

  • Changer of color in scales
  • Visible gray spots
  • Lesion on the fish and over its mouth
  • Peeling away the scales


This infection is persistent among fish that live in cold water. It is a parasite illness that is harder to identify in its initial phases and only identifiable once it has progressed to an advanced state. As a result, the fish demands your immediate attention once discovered. 

Ichthyobodo, a protozoan parasite, is the source of this illness. To treat costia, you can use sea salt or antibacterial medications like Nifupirinol. The following are some of the signs and symptoms:

  • Itchiness
  • Grayish or white spots

Fungal infection

This is a complex issue to deal with. To begin with, distinguishing a fungal disease from a bacterial attack might be challenging owing to several very similar symptoms.

Another issue with fungal infection is its diversity since the fungus has a massive variety, and it is tough to pinpoint the specific fungus that is causing the illness. Poor water condition, stress, untreated injuries, and other factors contribute to fungal infections.

You may use Erythromycin or add a teaspoon of sea salt per gallon in the water. The sign of a fungal infection is the cottony growth on the body, eyeballs, fins, or gills.

Flukes on the gills

Skin and Gill flukes are microscopic parasitic worms with a wormlike appearance and a tiny size. Therefore, they are difficult to notice with the naked eye. The good news is that flukes are common in aquariums and are typically harmless under normal conditions.

Overcrowding, incorrect water conditions, stress, and other factors contribute to the development of flukes. Most fish keepers suggest a spoonful of sea salt per gallon to heal skin and gill flukes. They have the following symptoms:

  • Itchiness
  • The gills and skin become red
  • Effort in breathing
  • Excessive mucus present on the skin

Fin and tail rot

Poor water quality, agitation, and untreated past damage induce fin and tail rot, a bacterial illness. These bacteria eat the fins and tails of the fish, causing them to become ragged.

If this illness is not treated, your fish may develop full-body rot, in which the bacterium consumes the whole body. Furthermore, the decay might lead to fungal diseases in the future. Fin and tail rot may cause the following symptoms:

  • Cuts in fin or tail
  • Discoloration of fins and tail


Betta Macrostoma is a unique and beautiful Betta species. The rare Betta Macrostoma is both entertaining and challenging (and costly) to keep. You may have difficulty finding this fish since it is an endangered species; however, keeping and breeding it is a desirable objective for any fish keeper.

Simply keep it away from other fish, provide it with appropriate environmental conditions, and attend to its requirements regularly. Once you’ve mastered all of this, you’re ready to take on the role of a Betta Macrostoma parent!


How many Betta Macrostoma can live together?

As Betta Macrostoma aren’t aggressive, you can keep two in a 20-30 gallon tank.

Richard Parker

Richard is an avid aquarist and has been keeping betta fish and other freshwater fish since he was a young boy. Through Aquatic Buddy, he hopes to help others learn how to care for their betta fish so they thrive in their home environments.