Spotfin Betta (Betta macrostoma) Overview and Care Guide

The Betta macrostoma may be on the “dream list” of every Betta enthusiast. This species of Betta also goes by the name of Spotfin and the Brunel Betta.

Unfortunately, B. macrostoma can be difficult to find. This is due to them being illegal to export from their region of origin, Brunel because they are on the endangered list. In fact, from the 30s to the 90s, B. Macrostoma was thought to be extinct. 

Since their rediscovery, the demand for this “exotic” fish has been on the rise which has caused unscrupulous people to poach them from the waters and ship them to Sarawak in Malaysia (where they are not protected by law) and shipped to retailers or directly to customers. 

For this reason, we strongly recommend only purchasing a Spotfin Betta from a reputable breeder.

If you’re interested in Betta macrostoma, read on for some information, fun facts, and pro tips about keeping this fish happy and healthy with our overview and care guide. 

Spotfin Betta


Appearance of the Betta macrostoma

Like most Betta species, B. macrostoma is a beautiful fish; however, it does lack those long-flowing fins of its cousins. What they do possess is a bright orange colour and a small dorsal fin that features a black and orange eye-like spot (which is how they got their nickname, Spotfin Betta).

They also have black stripes and orange patches on their caudal fin while the other fins are dark orange with a black edge. This Betta can grow up to 4.5 inches, with an average length of 3.5 inches. 

Another distinguishing feature of B. macrostoma is its large mouth. Unlike other Betta species, the Spotfin is a mouthbrooder (keep their fry in their mouth) rather than a bubble nest-maker

Betta macrostoma can live on an average of 3 to 5 years in captivity; however, with the right conditions, some have been known to live up to 10 years.

Spotfin Betta Care

No Betta species should have to spend its life in a tiny cup, vase, or other cramped containers. When it comes to the B. macrostoma, you will need very specific conditions for it to survive and thrive. 

Tank Requirements & Setup

To keep the Betta macrostoma it is recommended to have at least a 20-gallon tank per pair – these are active fish that need plenty of space to swim and explore. 

Since B. macrostoma are better suited to live in a small group, you may choose this option; however, you will need at least a 50-gallon tank to do so.

You will also need a heater set to between 75 and 79 degrees Fahrenheit and a target pH range of 6 to 7. Be sure to monitor your pH level regularly as drastic drops or elevations can be detrimental to your fish. 

This species of Betta is very sensitive to ammonia, nitrates, and nitrites in higher levels. To help prevent these toxins, be sure to include a good filtration system. The filter should be a low/slow-flow sponge system. Like most Betta species, the Spotfin doesn’t like fast-flowing water and will avoid or even hide from a filtration system with a powerful intake and output. 

For maintenance of the macrostoma habitat, remove 10 to 20% of the water once or twice a week using an aquarium vacuum. Gently go over the substrate (if using gravel or sand) to remove debris and fish waste. Replace with treated water at the proper temperature to avoid shocking your fish.

Betta Imbellis needs a well-planted tank (live plants) to provide plenty of shade for hiding and resting amongst. Tall, leafy plants such as the Amazon Sword, Anubias, and Ludwigia make excellent coverage for the Betta tank

Since this species does enjoy a dimmer atmosphere, you may also want to choose the addition of Indian Almond leaf which will add beneficial tannins to the environment and will naturally darken the water.

Speaking of light, do not add harsh aquarium lighting to the macrostoma aquarium. In their natural environment, this fish prefers the shade provided by the jungle canopy, so if your light is too bright, it will stress your fish out. Use an aquarium light that can be adjusted to dim and add floating plants (such as Amazon Frogbit) that will block out some of the brightness. 

The Betta macrostoma is also a good jumper, so be sure to have a hood or lid on your aquarium to prevent your fish from escaping.

Feeding the Betta macrostoma

The B. macrostoma is an omnivore but prefers protein. In the wild, this species will dine on a variety of insects, larvae, and other invertebrates, as well as fallen leaf litter. 

For us to duplicate this as best we can, feed your Betta macrostoma a varied diet consisting of mostly live, freeze-dried, or frozen foods such as bloodworm, daphnia, and brine shrimp. This breed of Betta does not do well on processed flakes or pellet-type diets.

Pro Tip: Do not overfeed your Betta. This can lead to constipation, bloat, and even death. To avoid this, feed small amounts twice daily or as much as can be consumed in a minute.

Betta macrostoma and Tankmates

Although this Betta species is less aggressive than their long-finned cousins, it is recommended to keep them with other Betta macrostoma. Since this Betta has a large mouth, it would be possible (and likely) that it would dine on smaller fish. 

What about larger species with macrostoma?

This is also not recommended as a larger fish may bully the Betta which can lead to stress and illness. 

To house multiple macrostoma you will need at least a 20-gallon tank for one male and one female. If you want to keep more than two, you are looking for at least a 50-gallon tank with plenty of separate areas where males can stake out their territory. 

Even with lots of space, males can still show aggression toward each other. 

Common Health Issues of the Spotfin Betta

As with any fish, the B. macrostoma is susceptible to some common ailments. 

  1. Bacterial Infections – this may present itself as red streaks on the scales and fins. 
  2. Cotton Mouth – symptoms include grey spots on the body, lesions on the back, and discoloured scales.
  3. Skin/Gill Flukes – symptoms include red skin and laboured breathing.

One way to help prevent illness in the B. macrostoma is to perform regular tank maintenance. Polluted water with high levels of ammonia, nitrates, and nitrites is a vehicle for illness. Keep an eye on the pH levels and temperature as well to ensure your Spotfin Betta stays healthy and happy. 

Betta macrostoma Overview and Care Guide Conclusion

If you love the Betta species and want a more peaceful specimen, then the macrostoma may be the one for you. This lovely Betta sports shorter fins with a red spot on the top fin and are considered more docile than its long-finned counterparts.

B. macrostoma can tolerate living with other Spotfins, but you will have to have at least a 50-gallon aquarium to house five or six macrostomas. However, if you want just one male and one female, a 20-gallon tank will be adequate. 

Like all Betta fish, we recommend providing the macrostoma species with plenty of live plants and perhaps, even, an Indian Almond leaf for those beneficial tannins. Of course, they will also need a low-flow filter, heater, low light, and regular tank maintenance to keep them healthy.

Unfortunately, you will also have to keep an eye open for some common diseases and feed the Spotfin a diet of mostly live, freeze-dried, or frozen foods as processed flakes and pellets are not healthy for the macrostoma species. 
Lastly, we want to emphasize the fact that the Spotfin is considered an endangered fish, so never purchase one that has been snatched from the wild. It is not only unhealthy for the fish but it is illegal for these fish to be exported from their native habitat.