Betta mahachaiensis: The Exquisite Jewel of Thailand’s Brackish Waters

In the verdant, sprawling mangroves of Thailand, a particular aquatic marvel has captivated both enthusiasts and ecologists alike: the Betta mahachaiensis. This lesser-known cousin to the ubiquitous Siamese Fighting Fish (Betta splendens) stands as a testament to the awe-inspiring tapestry of nature’s diversity. Recognised for its majestic colour palette and remarkable adaptability, the Betta mahachaiensis not only illuminates our home aquariums but also provides keen insights into the evolutionary dynamics of brackish water habitats. This article seeks to unveil the fascinating world of this unique betta species, shedding light on its intriguing habits, delicate conservation status, and its profound resonance in the ornamental fish community. Dive with us as we journey into the depths of Thailand’s enigmatic waterways, where the Betta mahachaiensis gracefully reigns supreme.

A tranquil nipa palm swamp in Samut Sakhon, Thailand, with cloudy brackish waters. Here, the vibrant Betta mahachaiensis fish navigate gracefully among the palms’ roots in their natural habitat.

History and Discovery

Betta mahachaiensis was first discovered in the Samut Sakhon Province of Thailand, specifically in the Mahachai area which lent its name to the species. It was scientifically described by Dr. Narongrit Muangmai, Dr. Chaiwut Grudpun, and Dr. Niwat Sriwanich in 2017. This discovery was significant because, until then, this unique Betta species had gone unnoticed, overshadowed by the more popular and widely-recognized Betta splendens.

Betta mahachaiensis stands out from its relatives due to its striking coloration and its ability to thrive in brackish water environments, which are a mix of freshwater and saltwater. It’s particularly adapted to survive in mangrove habitats, which often undergo changes in salinity.

The introduction of Betta mahachaiensis to the global Betta community was met with much excitement, as it represented not only a new challenge for breeders and aquarists but also shed light on the rich biodiversity of the Betta genus. However, as interest grew, concerns about over-collection from the wild and the potential threats to its natural habitat arose. This has led to increased conservation efforts and campaigns to educate both hobbyists and the public about responsible fishkeeping and the importance of preserving the natural habitats of such unique species.

Today, the history of Betta mahachaiensis is still being written as researchers continue to study its biology, ecology, and behavior, while conservationists and enthusiasts work together to ensure its continued survival both in captivity and the wild.


The Betta mahachaiensis, a unique species of fish, is native to a limited range of localities in central Thailand, specifically in Bangkok, Samut Sakhon, Samut Songkhram, and Samut Prakan provinces. These sites are situated along the Gulf of Thailand’s coast. Notably, many of these habitats are in close vicinity to Bangkok, a city undergoing rapid expansion. As a consequence, these habitats are facing severe threats, compromising the survival of Betta mahachaiensis in its natural environment. Recent surveys have indicated troubling signs, with no conclusive evidence of the species’ presence in both Samut Songkhram and Samut Prakan. Moreover, it’s important to note that populations from different localities display minor morphological variations, such as differences in the shape of the caudal-fin, ranging from rounded to ovate. To maintain the purity and distinctiveness of these populations, it’s essential to avoid intermixing or hybridizing them in aquaria settings.


The Betta mahachaiensis, a majestic inhabitant of brackish coastal swamps, finds solace amidst the verdant embrace of the nipa palm, scientifically termed as Nypa fruticans. This unique palm stands as the sole member of its species tailored to thrive in estuarine domains. The males of this fish species ingeniously weave their bubble nests ensconced amidst the sturdy branches or within the tree’s protective bracts, providing them a haven against potential threats. Notably, while other Betta species such as B. imbellis and B. splendens have occasionally been found in brackish locales, the Betta mahachaiensis is singular in its unwavering preference for such habitats. In the picturesque terrains of Samut Sakhon province, the pH levels oscillate between 6.87 and 7.80, and salinity measurements span from 1.1 to 10.6 ppt. The aquatic tapestry of this region is further enriched with fish species like Trichopsis vittata, Trichopodus trichopterus, and a bevy of others, adding layers of biodiversity to these saline waters.


Unveiling the intricate morphology of the Betta mahachaiensis, a specimen boasting a standard length oscillating between 50-60 mm, its uniqueness is rooted in the picturesque coastal subdistrict of Mahachai in the Samut Sakhon province, just south of Bangkok’s bustling streets. Although historically misinterpreted as a mere hybrid, contemporary molecular and morphological examinations vindicate its status as a bona fide species. This aquatic marvel is distinguishable by its deep brown-to-black base body hue, accentuated by a shimmering patina of iridescent green to bluish-green. Notably, two parallel gleaming bars elegantly grace its opercle. Contrary to its congeners, the Betta mahachaiensis bears no trace of red streaks or patches on its opercular membrane. Furthermore, its dorsal fin showcases transverse black bars, in sharp contrast to the caudal-fin which is devoid of such bars, yet punctuated by minuscule black spots that hug the internal rays. One must note its meticulous proportions: the head spanning 24.9-31.2% of its standard length (SL), and the dorsal fin base contributing 12.2-19.3% SL. Nestled within the Betta splendens complex, this species shares quintessential traits like an iridescent iris, and striking body hues. However, it distinctly flaunts vertical blue bars on its opercle and a blue-hued 1st pelvic-fin ray. This slender-bodied marvel is an epitome of nature’s artistic flair.

A striking pair of Betta mahachaiensis, their vibrant colors shimmering, flare impressively at one another, showcasing their elaborate fins in a captivating dance.


For enthusiasts desiring to keep the exquisite Betta mahachaiensis, it’s paramount to provide an aquarium spanning at least 45 x 30 cm, suitable for a pair. This species flourishes in medium-hard to hard water, even showing a predilection for slightly brackish conditions. A shaded environment abundant with tall stem or floating plants offers the ideal setting, while driftwood adorned with Microsorum or Taxiphyllum spp. plants enhances the ambience. Amenities like small clay pots and even nostalgic empty camera film cases can be perfect hideaways. To mimic their natural habitat, introducing dried leaf litter like beech, oak, or Ketapang almond leaves is advised. Besides offering more shelter, these leaves facilitate microbial growth, becoming a delectable treat for the fry. Their gradual decomposition releases beneficial tannins and other chemicals. As Betta mahachaiensis hail from serene waters, a robust filtration is unnecessary; a gently-turning air-powered sponge filter will suffice. A word of caution: always ensure a tank lid, as this species is an adept jumper and requires sporadic access to the humid air layer above the water. Key water parameters to maintain include a temperature between 22 and 28°C, pH levels ranging from 7.0 to 8.5, and a hardness between 90 to 357 ppm.


In the pristine habitats where Betta mahachaiensis flourish, these regal aquatic marvels predominantly source their sustenance from insects and an array of diminutive invertebrates and zooplankton. Whilst under domesticated care, these fish, although initially tentative, gradually grow accustomed to dried provisions, discerning them as sustenance. Nonetheless, to ensure the apotheosis of their luminous hue and vigour, it’s paramount to frequently lavish them with a selection of live or frozen feasts such as Daphnia (Daphnia pulex), Artemia (Artemia salina), Glassworms (Chaoborus larvae), Blackworms (Lumbriculus variegatus), Tubifex (Tubifex tubifex), Whiteworms (Enchytraeus albidus), and Bloodworms (Chironomus spp.). In addition, minuscule insects like ants or fruit flies can emerge as culinary delights, especially if their digestive systems are enriched with fish flakes or vegetative matter, thus amplifying their nutritional stature for the Betta. Exercising prudence in feeding is critical, as Betta mahachaiensis seems innately vulnerable to unhealthy weight accumulation.

A dense culture of wriggling white worms, thriving in a moist medium, presents as an ideal nourishing feast for Betta fish.

Nature and Coexistence

Among the captivating species in the aquatic world, Betta mahachaiensis stands out due to its distinctive behaviour and compatibility requirements. While many might be inclined to integrate it within conventional community aquaria, such a course is not advisable. This species flourishes best in solitude or in the company of exceedingly placid tankmates. More robust or active species may overshadow and dominate them. While certain diminutive cyprinids and loaches, natives of analogous natural habitats, might be considered companionable, introducing other species, especially during breeding episodes, might become an undue distraction. To preserve their well-being, and ensure successful breeding, it’s wise to provide ample cover, disrupted sightlines, and in many instances, it’s prudent to separate pairs into exclusive breeding quarters.


The Betta mahachaiensis, a captivating species, showcases significant sexual dimorphism with males boasting vibrant hues and grandiose fin extensions, in stark contrast to their more demure female counterparts. As bubble-nesters, it is paramount to set up a dedicated breeding tank with an impeccably sealed cover – with some aficionados even resorting to clingfilm – ensuring a warm and humid airspace, vital for the optimal development of the fry’s labyrinth organ.

Interestingly, it isn’t imperative to segregate the pair before the spawning process. The male, in his preparation, might opt to weave his nest beneath a broad leaf, within a canister, or amidst delicate surface foliage. He tends to be rather protective, only allowing the female’s proximity upon its completion. Pre-spawning, the female’s body undergoes a fascinating transformation, with her colour fading and the emergence of dark lateral bands. The spawning, an intimate ritual, sees the male enveloping the female, releasing milt and eggs simultaneously. Post this embrace, the male becomes the guardian, meticulously transferring the eggs to the nest, while the female retrieves any strays.

Once spawning culminates, while the female’s role diminishes, the diligent male remains the protector, watching over the nest. Post-hatching – typically within a day or two – the larvae remain nestled for an additional few days, relying on their yolk sac. Meanwhile, the ever-watchful male continually ensures their safety, even moving the nest if danger lurks. As the fry begin their free-swimming phase, the male’s interest wanes, but reassuringly, the adults rarely pose a threat to their progeny.

In terms of nourishment, initially, an infusoria-rich diet suffices. Subsequently, offerings of microworm and Artemia nauplii are introduced, though caution is urged against excessive Artemia, given potential health concerns. For optimal growth, diverse food offerings in small quantities, served 2-3 times daily, are recommended. Water change practices should be approached with care, favouring frequent minor adjustments over sporadic major ones.

An impressive Betta mahachaiensis male displays radiant hues and intricate fin patterns, exuding confidence and elegance in his aquatic realm.

Possible Hybridisation

In the refined realm of ichthyological pursuits, the Betta mahachaiensis holds a distinct and enviable position, famed not only for its captivating hues but also its fascinating provenance. Recent discourse within the community, however, sheds light on the possible hybridisation of this exquisite species. While there’s an undeniable allure to crossbreeding for enhanced aesthetic appeal or novel traits, it becomes imperative, especially for the purists, to underscore the significance of maintaining and propagating pure lines. Breeding fish from specific, authenticated localities not only ensures the preservation of their genetic integrity but also champions the cause of keeping these aquatic jewels untainted for generations to come. As custodians of these aquatic wonders, it behoves us to perpetuate their purest form, ensuring that the Betta mahachaiensis’s lineage remains as pristine as its natural habitat.

Alien Bettas

In the distinguished realm of ornamental aquatics, the Betta mahachaiensis commands a unique reverence, having been meticulously interwoven, on a genetic tableau, with illustrious species such as B. splendens, B. imbellis, B. smaragdina, B. siamorientalis, and B. stiktos. This genteel confluence has ushered in the birth of the ‘Alien Bettas’, a mesmerising spectrum of colour morphs hitherto unseen in their pristine wild environs. Such a harmonious blend not only celebrates the wonders of genetics but also spotlights the expansive horizons within the art of aquatic breeding, showcasing the possibility of creating aquatic tapestries rich in colour and diversity.

A mesmerizing Copper Alien Betta male stands out, boasting iridescent copper scales and extravagant fin designs, a stunning result of hybridizing Betta mahachaiensis with members of the Betta Splendens Complex.


Betta mahachaiensis, a distinctive member of the Betta species, stands out not just for its vibrant appearance but also for its unique habitat preferences and survival adaptations. Native to the brackish and freshwater habitats of Thailand, this fish serves as a testament to nature’s ability to evolve and adapt to specific environmental niches. The critical status of its natural habitat, largely due to human activities such as urbanization, underscores the importance of conservation efforts. As aquarists, hobbyists, and researchers increasingly recognize the intrinsic value of Betta mahachaiensis, there arises a pressing need to foster sustainable breeding practices and habitat preservation. This species is not just a visual delight for those who keep them in aquariums, but also an ecological marker that emphasizes the delicate balance of freshwater ecosystems in our rapidly changing world. Ensuring its survival is not just about preserving a single species, but about respecting and upholding the rich biodiversity of our planet.