The Betta mandor fish, officially named Betta mandor by scientists, belongs to the family Osphronemidae. Before this species was scientifically described in 2006, it was nicknamed "Ninja Betta." This name was given due to its dark coloration and the presence of two bright stripes on its head, which resembled the eye slits on the traditional black attire of these Asian warriors. The similarity is not limited to appearance: these fish are known for their complex behavior. Males are known to actively compete for territory and the attention of females, and sometimes even attack other species with similar coloration.

Tank
from 50 L (13 gal)
Temperature
22 – 27 °C (72 – 81 °F)
Size in aquarium
5 – 6 cm (2 – 2.4 in)
Acidity
pH 4–6
Natural rangeRange on the map
  • West Kalimantan area
  • Mandor area
  • Indonesia

Tank conditions

Plan the tank stocking
Temperature
22 – 27 °C (72 – 81 °F)
Water pH
Acidic (4) – Slightly acidic (6)
Water dH
Very soft (1) – Soft (5)
Water salinity
no salt (freshwater)
Size in aquarium
5 – 6 cm (2 – 2.4 in)
Lifespan
5 years
Temperament
Semi-peaceful including aggression during spawning / intraspecific conflicts
Toward small fish
not a predator
Required aquarium volume
from 50 L (13 gal)
Lighting
dimmed
Substrate
any, but dark
Water flow
none or stagnant (no flow)
Feeding
Any (universal)
Keeping
Pair (male/female)
  • Lifespan. A lifespan to expect under good care, not a measured value: it depends heavily on tank volume, water quality and diet — and for selectively bred forms, on their origin as well.
  • Toward small fish. Based on the Predators category in the catalog or the temperament in the species parameters. “A risk to small fish” means the species is not a predator by habit, yet will swallow any fish that fits in its mouth.
  • Required aquarium volume. This is a husbandry recommendation, not a measured value: the volume depends on the keeping mode (pair (male/female)), footprint, decor and tank mates.

Care and keeping

Description

This species is a close relative of Betta foerschi, sharing many features in its body pattern. Adult specimens reach a length of 5 to 6 cm. The fish's body appears elongated and slender. Males are generally larger than females, their unpaired fins are more developed and have a rich dark coloration, and the characteristic orange stripes are located just behind the head. Females, on the other hand, appear lighter, with their coloration predominantly gray.

Habitat

The natural habitat of this species extends across Southeast Asia, specifically the Indonesian part of Borneo island, in the West Kalimantan province. The first specimens for scientific description were collected in 2006 in the Kapuas River basin, between two settlements – Mandor and Anjungan. Betta mandor prefers to inhabit shallow streams and small rivers that flow through dense tropical forests. The depth of such bodies of water is sometimes only a few centimeters, and the dim light penetrating through the tree canopy does not hinder the active growth of riparian and aquatic vegetation. The bottom of these bodies of water is often covered with fallen leaves, twigs, and grass. Their decomposition process leads to the release of humic acids and other organic substances, which give the water its characteristic brown tint.

Behavior and Compatibility

These fish belong to the fighting fish group, which immediately indicates their challenging temperament. However, information about the behavior of Betta mandor is quite contradictory. It is sometimes claimed that males show extreme intolerance towards rivals and other related species with similar coloration. Moreover, an alpha male may even harass individual females. At the same time, other authors note that conflicts, though not uncommon, are mostly demonstrative and rarely lead to injuries. Based on this, it can be concluded that in a small aquarium, it is recommended to keep one male in the company of one or several females, as well as with non-aggressive fish species that do not resemble males. In more spacious aquariums, the restrictions are not as strict.

Care and Maintenance

For a pair of fish, the optimal aquarium volume starts from 40 liters. The decorative arrangement can be anything and depends entirely on the aquarist's taste and capabilities. However, if conditions mimicking the natural environment are created, Betta mandor will look most harmonious. It is recommended to use dim lighting, place driftwood and shade-loving plants against a dark substrate. The bottom can be covered with a layer of certain tree leaves. They serve not only as a decorative element but also release tannins, such as humic acids, which is characteristic of the natural habitat of these fish. The fish prefer warm, slightly acidic, and very soft water, which should be changed weekly. For biological balance, the uninterrupted operation of the installed equipment and regular removal of organic waste, such as food remnants and excrement, are important. It is important to remember that Betta cannot tolerate strong or even moderate currents and needs a warm, humid layer of air at the water's surface. The first problem is solved by correctly choosing a filter that regulates water movement, and the second by installing a lid on the aquarium.

Diet

This species is omnivorous. They readily accept most common aquarium foods, whether dry, frozen, or live. The latter include Artemia, Daphnia, bloodworms, as well as Drosophila flies, mosquito larvae, and other small insects. The market offers many specialized products from various manufacturers, developed specifically for Betta fish; these can well form the basis of their diet.

Breeding and Reproduction

In natural conditions, these fish live in a rather challenging environment that is subject to seasonal changes, where some forest streams may dry up or turn into mud. Through evolution, they have developed a unique mechanism for protecting their offspring during the most vulnerable period – the egg stage. The male carries the fertilized eggs in his mouth; they enter there immediately after spawning. After 8–14 days, fully formed fry emerge. Successful breeding requires only sexually mature male and female, as well as a favorable environment and quality nutritious feeding. Instincts will take care of everything else.

Diseases

Most health problems in fish often arise from unsuitable keeping conditions. Maintaining a stable and comfortable habitat is a key factor for successful keeping. If symptoms of illness appear, the first step is to check the water quality. If deviations are found, it is important to take immediate measures to eliminate them. If the symptoms do not disappear or worsen, medicinal treatment may be required.

How to choose

When purchasing Betta mandor, it is important to choose active individuals with clean, undamaged fins. Avoid fish with signs of emaciation, sunken bellies, or film on their bodies, as this species is sensitive to transport and keeping conditions. It is recommended to acquire fish from reputable breeders specializing in wild species to guarantee genetic purity and the absence of parasites. — pay attention to behavior: healthy fish should be curious, not sluggish or constantly hiding — ask the seller what type of food the individual is accustomed to, as wild species can be selective eaters — check the integrity of the scales and the absence of unnatural spots, which may indicate bacterial infections.

Compatibility

There are no pair reviews for this species yet — check tankmates in the matcher.

All tankmates

Plants and this fish

Matching water does not mean the plant will stay intact.

Frequently asked questions

The essentials: size, tank volume, water parameters and care

How big does Betta mandor get?

An adult reaches 5–6 cm in length. Plan the tank around the maximum size: the fish quickly outgrows a cramped setup.

What size aquarium does Betta mandor need?

The recommended volume is 50 L. A smaller tank speeds up nitrate build-up and raises stress levels.

What water parameters does Betta mandor need?

Temperature 22–27 °C, pH 4–6, hardness 1–5 dGH. Stability matters more than exact values: sudden swings are harder on the fish than a small deviation from the ideal.

How long does Betta mandor live?

Around 5 years when kept properly. Lifespan depends directly on tank volume, water quality and a varied diet.

Is Betta mandor aggressive?

Temperament: semi-peaceful (including aggression during spawning / intraspecific conflicts). Keep this in mind when choosing tank mates.

How many Betta mandor should be kept together?

Recommended setup: pair (male/female). Ignoring this is a common cause of stress and disease.

What does Betta mandor eat?

Diet type: any (universal). Feed small portions that are finished within a couple of minutes — overfeeding does more harm than underfeeding.

What is the scientific name of Betta mandor?

The scientific name of the species is Betta mandor, family Osphronemidae.

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Other scientific names and conservation status

Categories
Labyrinth fish
Conservation status
EndangeredEN