Betta macrostoma (Brunei Beauty) Ultimate Guide

Betta macrostoma

Betta macrostoma (Brunei Beauty) Facts

Scientific Name: Betta macrostoma
Common name: Spotfin Betta or Brunei Beauty
Family: Osphronemidae
Origin: Brunei and northern Sarawak, Borneo
Usual size in tank: 6.7 cm SL male/unsexed
Recommended temperature: 24°C – 26°C
Recommended pH range for the species: 4.4 – 5.7
Recommended water hardness (dGH):0 – 12°N (0 – 197.46ppm)
Aquarium:        Betta macrostoma comfortably coexist in pairs, species tanks, and community tanks. You need a 20 gallon tank to functionally house a pair. Look to house groups in a 40 gallon tank or larger. Use caves and dense plants to give cover to pairs, which they need during spawning.
Tank preferences:Middle levels
Water Conditions:Betta macrostoma are usually easy to manage. They are very tolerant of water chemistry and thrive in almost any type of clean and filtered water. Ideally the temperature should be kept cool in the mid-70s F.
Reproduction & Sexing:Betta macrostoma males are more intensely colored then females. During breeding, males are brilliantly colored black and orange to red. Females have two lateral bands while the male does not. You can easily spotlight females to observe their ovaries.
Macrostoma is a paternal mouthbrooder and the male incubates from 12 to 17 days with 14 days being very consistent. Incubation time can vary with water temperature. Females normally initiate spawning. Soft water with pH below 6 will induce spawning.
Temperament to its own species: peaceful once you have paired them
Temperament towards other fish species:peaceful once you have paired them
Similar Species:Similar species would be unimaculata complex members.
Lifespan: The expected lifespan for Betta macrostoma is about 8 – 10 years. With good care and feeding you could extend their life.

Betta macrostoma (Brunei Beauty) Generalization

Betta macrostoma is often called a big mouth fighting fish.

It was only discovered a few years ago in the rainforest areas of Brunei on the island of Borneo.

In the wild it normally populates shady pools in the upper reaches of the rivers with extremely acidic water. Such environmental conditions have a bactericidal effect, so the fish has no immune defense.

In the aquarium it is at the mercy of infectious diseases and is also extremely sensitive to the bacteria involved in the biological breakdown processes. This makes maintenance difficult under normal aquarium conditions.

Betta macrostoma (Brunei Beauty) Habitat

In the wild the fish inhabit very narrow distribution areas in the rainforest of Brunei on the island of Borneo.

Betta macrostoma

There the fish live in up to 2m deep pools between the rocky terrains. The water there is extremely acidic (pH <4). This makes maintenance under aquarium conditions extremely difficult.

In their waters, the acidic water creates an absolutely sterile environment. The fish are therefore not only at the mercy of infectious germs, but also in and of themselves non-pathogenic bacteria, which are involved in the organic breakdown processes in the aquarium filter and in the decomposition of leftover food and soil sludge.

Shallower water hollows are completely filled with rotting fallen leaves. In this milieu, the macrostoma fish lead a much hidden life and only come out of their hiding place to snap at mosquito larvae or other prey.

In the wild, the males Betta macrostoma display a blaze of color that specimens bred under aquarium conditions never achieve. Only in their original home waters do they live up to their second name, “peacock-eye” fighting fish.

Betta macrostoma Characteristics, Shape and Color

Male Betta macrostoma

  • It has a reddish body color with blue
  • It has yellow banded gill covers
  • It also has wide black and yellow horizontal stripes on the caudal fin
  • In the lower half of the dorsal fin, most males have a black, yellow-bordered spot. Hence the second name of the species – “peacock-eye” fighting fish. However, this eye spot can also be completely absent

Female Betta macrostoma

  • They are less colorful
  • Their basic body color is an inconspicuous dark brown
  • They also stay smaller than the males
Betta macrostoma
Female Betta macrostoma

Betta macrostoma in the Aquarium

  • Betta mascrostoma are loners. No more than one pair should be kept in the art basin with a minimum length of 80cm
  • Keep them in pairs for breeding purposes. Both males and females will be aggressive towards each other until they’re paired off.
  • The water level can be 40cm high
  • There should be a few centimeters between the water surface and the cover so that the fish can occasionally supply their labyrinth organ with warmed air
  • Betta macrostoma are extremely good jumpers. The aquarium must therefore be completely covered with one or two panes of glass
  • In nature these fish live in an extremely acidic environment. Therefore, the pH value in the aquarium should be at least between 5.5 and 6.5, but never higher
  • In order to do justice to the aquarium, the aquarium must be extremely clean; i.e. the filter must be cleaned regularly, a partial water change must also be carried out weekly and the aquarium water exchanged for fresh water that has been adjusted to the water values ​​beforehand
  • A UV clarifier downstream of the aquarium filter should be added to help with disinfection. This is the only way to keep the germ count in the aquarium at a low level
  • The water temperature should be between 24 and 26 ° C
  • Thanks to their big mouth, the Betta macrostoma can also cope with larger chunks of food: They greedily snatch for insects, mosquito larvae and even smaller fish; Forest and dry fodder is also accepted.
  • DO NOT feed them Tubifex or red mosquito larvae, as both of them bring in wastewater bacteria from their muddy surroundings.

Betta macrostoma Breeding

Mating and spawning take place in the mouth-brooding Betta macrostoma similar to Betta picta.

What is unusual for macrostoma is that the female is initially the more active partner.

  • First it attacks the male, who then reacts with gestures of humility
  • Then the female tries to nudge the male with her mouth in the flanks and push it to motivate him to be entangled
  • The male wraps around the female and then turns her on her back. Then the male forms a U-shaped curve with his caudal fin
  • The male holds still while the female picks up the eggs from the male’s U-shaped curved caudal fin
  • This spawning process repeats itself over and over again, with the pauses in between getting longer and longer, but the number of eggs increasing. In this way, up to 80 eggs come together.
  • During the whole process, it is the female who vigorously pushes away other Betta.
  • Any fish larvae that have been accidentally spat out – for example under stress – are collected again after some time by the father and kept in the mouth
Betta macrostoma breeding

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