Unveiling Betta siamorientalis: The Hidden Gem of Southeast Asian Freshwaters

Betta siamorientalis


Betta siamorientalis, a lesser-known yet captivating member of the Betta species, remains a jewel within the aquatic realm. Native to the freshwater environs of Southeast Asia, this remarkable fish presents an enthralling blend of elegance and resilience. Delve into the mysterious world of Betta siamorientalis as we uncover its characteristics, habitat, and the pivotal role it plays in the ecosystem. Whether an aquarist seeking knowledge or a curious nature enthusiast, this article promises to enrich your understanding of this magnificent species.

History and Discovery

Betta siamorientalis, a riveting species first brought to the limelight on 10th December 2012, boasts an origin story rooted in the rich tapestry of Southeast Asian aquatic biodiversity. The name ‘siamorientalis’ gracefully encapsulates its geographical lineage, melding ‘Siam’ — the erstwhile moniker for Thailand — with the Latin ‘orientalis’, translating to ‘of the east’, a fitting homage to its discovery in the eastern precincts of Thailand. The unveiling of this species was meticulously documented in a seminal paper by Chanon Kowasupat, Bhinyo Panijpan, Pintip Ruenwongsa, and Tadsanai Jeenthong, who highlighted its unique characteristics. Notably, the Betta siamorientalis sets itself apart within the Betta splendens group, particularly from its congener, Betta imbellis, with its distinct slender body adorned by reddish vertical bars upon a pronounced black opercle. Its intriguing dark-brown to black body hue, coupled with the contrasting red crescents on the caudal fin rays, gives it a mesmerising aesthetic appeal. Indeed, its introduction to the annals of ichthyology offers both enthusiasts and scholars a captivating insight into the diverse wonders nestled in the waters of eastern Thailand.


The Betta siamorientalis, whilst remaining an enigmatic presence in the aquatic world, showcases a commendably broad distribution within Southeast Asia. Its known habitats span a diverse geographical range, with its presence authenticated in the provinces of Chachoengsao, Sa Kaeo, Prachin Buri, and Chon Buri, all nestled in the picturesque landscapes of eastern Thailand. Additionally, its trace has been identified westward in Banteay Meanchey province of Cambodia, a region sharing its borders with Sa Kaeo, and further extending to an unspecified locale in Vietnam. This suggests a rather expansive territorial range for the species. Of particular significance is the ‘type locality’, pinpointed precisely at Sai Hai village, situated in the Tha Thonglang subdistrict of the Bang Khla district within Chachoengsao province, Thailand. This exact locale, marked by coordinates 13°42′ N, 101°13′ E, serves as a vital reference point for ichthyologists and aquatic aficionados delving into the study and appreciation of this distinctive species.

Chachoengsao Province, Thailand.
Chachoengsao Province, Thailand.


The enchanting Betta siamorientalis thrives within the calm embrace of still or leisurely moving waters. These serene environments are not just a sanctuary for its survival but also the very canvas upon which it constructs its unique bubble nests, a testament to its intricate reproductive behaviour. The species has been predominantly observed within the shallow expanses of freshwater marshes, flood-engorged fields, and the verdant stretches of rice paddies. Moreover, its presence graces the vegetative fringes of ponds, lagoons, ditches, canals, and other water bodies, making it a testament to nature’s intricate design.

Habitats of Betta siamorientalis
Habitats of Betta siamorientalis in Eastern Provinces of Thailand: Chachoengsao Wetlands Showcasing Diverse Aquatic Vegetation and Natural Water Bodies.

During field expeditions, certain aquatic plants stood out as common constituents of its habitat. Notably, Leersia hexandra from the Poaceae family and Eleocharis dulcis from the Cyperaceae family were frequently encountered, indicating their probable significance in the Betta siamorientalis’s ecological circle.

Further enriching the biodiversity of these habitats are the sympatric fish species that cohabit these spaces. Species such as Trichopsis vittata, Trichopsis shalleri, Trichopsis pumila, Trichopodus trichopterus, Anabas testudineus, Lepidocephalichthys hasselti, Pangio anguillaris, Macrognathus siamensis, and Monopterus albus all share this watery realm, painting a vivid picture of the aquatic diversity where Betta siamorientalis finds its home.


The Betta siamorientalis is a fascinating study in aquatic morphology, with characteristics that both intrigue and delight. Let’s break down its appearance for the lay reader:

Size and Shape:

  • The Betta siamorientalis has a compact head, accounting for approximately 28-34% of its standard length (SL).
  • Its eyes are quite prominent, filling almost a quarter to a third of its head length.
  • The body is streamlined, with its thickest point being around 23.6-32.1% of its standard length.
  • The dorsal fin (the fin on the top) starts just beyond the body’s midpoint and has a rounded edge.
  • Its tail fin, known as the caudal fin, is also rounded at its margin.
  • The pelvic fins (the pair near the front underside) have a unique, sickle-shaped appearance.
  • The anal fin, located on the underside, is pointed and extends in males to half or more of the caudal fin’s length.
  • The largest recorded size of this fish is 32.7 mm in standard length.

Colouration in Males:

  • The male is dominantly dark-brown to black on the head, adorned with shimmering scales that shift between yellowish-green to bluish-green.
  • On the sides of the head, you’ll see two parallel reddish bars. The bar closer to the edge appears more vivid than its counterpart.
  • The body’s colour maintains the dark theme, but the iridescence of its scales gives it a radiant contrast.
  • The dorsal fin is similarly dark but shines with a yellowish to bluish-green glow between the fin rays.
  • The tail and anal fins are a mix of red-brown to black, embellished with iridescent spaces in between.
  • The tail fin boasts a red crescent at its edge, framed by a slim black outline.

Colouration in Females:

  • The female Betta siamorientalis presents a milder colour palette.
  • The head and body have a yellowish to light-brown hue, illuminated with the same iridescent greenish-blue scales seen in males.
  • The sides of her head bear two faint reddish bars.
  • She flaunts a distinctive stripe running across her body, which seems almost parallel to another stripe at eye level.
  • Her fins (dorsal, tail, anal, and pelvic) are predominantly yellowish, interspersed with delicate green to bluish-green shades.
  • In essence, the Betta siamorientalis showcases a delightful blend of slender morphology and vivid colouration, making it a species of unparalleled beauty in the aquatic realm.
Betta siamorientalis male and female
Betta siamorientalis: Acclimatised Live Male Paratype (30.9 mm SL) and Female Paratype (26.7 mm SL) from Sai Hai village, Tha Thonglang sub-district, Bang Khla district, Chachoengsao province, Thailand. Collected by C. Kowasupat et al. on 12th October 2010.


For those seeking to recreate the natural habitat of the Betta siamorientalis, careful consideration to the environment and conditions is paramount. Here’s a comprehensive guide on maintaining this magnificent species in captivity:

Tank Size & Setting:

  • Opt for an aquarium with base measurements of at least 45 x 30 cm to comfortably house a pair of these elegant fish.
  • A well-planted tank, reminiscent of their shaded natural habitats, is ideal. Incorporate a generous amount of surface cover using tall stem or floating plants.
  • Introduce driftwood roots and branches strategically to create inviting shady retreats.
  • Clay plant pots or lengths of piping are not just ornamental but also serve as excellent hideaways.
  • Enrich the environment with dried leaf litter. Not only does this add to the aesthetic appeal, mimicking their natural surroundings, but as the leaves decompose, they foster microbe colonies, offering an invaluable secondary nourishment source for the young. Moreover, the tannins released from these decaying leaves can be beneficial, especially for species accustomed to blackwater conditions.
  • However, eschew natural peat in your set-up. Its collection harms our environment and isn’t a sustainable choice.

Water & Filtration:

  • Recreate the tranquil waters of their native habitat by ensuring your filtration isn’t overly robust. A gently churning air-powered sponge filter suffices.
  • While it’s tempting to fill the tank to the brim, always leave some space at the top. Betta siamorientalis, like its Betta cousins, occasionally requires access to the humid air layer above the water – a behavioural quirk stemming from its natural habitat. A cautionary note: these fish are adept jumpers, so a well-covered tank is a must.

Optimal Conditions:

  • Temperature: Maintain a balmy 22 – 28 °C.
  • pH Levels: Ensure a slightly acidic to neutral range of 5.5 – 7.5.
  • Water Hardness: Aim for a range between 18 – 215 ppm.
  • By faithfully mimicking the Betta siamorientalis’ natural habitat, you’ll not only be treated to their most vibrant behaviours but also ensure their longevity and wellbeing.


The diet of Betta siamorientalis reflects its natural predisposition towards insects and minute invertebrates. For those nurturing this species in captivity, dietary considerations play a pivotal role in ensuring optimal health and vibrancy:

Natural Diet:

In the wild, these fish primarily feast upon insects and other small invertebrates, an inclination deeply rooted in their ecosystem.

small-size fruit fly (Drosophila melanogaster)
Small-sized Fruit Fly (Drosophila melanogaster): An Ideal Live Food for Betta siamorientalis.

Captive Feeding:

Whilst captive Betta siamorientalis may initially display hesitation towards dried feed, once acquainted, they readily partake. However, to truly ensure their vivid colouration and peak health:

Feeding Caution:

It’s paramount to exercise restraint in feeding. Betta siamorientalis have a notable susceptibility to weight gain, and moderation is key to preventing obesity.

Incorporating a diverse and controlled diet not only mirrors their natural feeding habits but also accentuates the beauty and vitality of this splendid species.

Nature and Coexistence

When contemplating the cohabitation of Betta siamorientalis in an aquarium setting, several vital considerations come to the fore:

Compatibility Concerns:

Though a visually arresting species, Betta siamorientalis doesn’t seamlessly blend into the typical community aquariums. Their specific needs and inherent disposition make them better-suited for solitary living or with non-aggressive co-inhabitants. Introducing larger or more vigorous fish can be counterproductive, as these tend to overshadow and outcompete the more reticent Betta siamorientalis.

Potential Tank Mates:

Certain small cyprinids and loaches, natural denizens of similar watery environments, can make for harmonious tank mates. However, due diligence is essential: thoroughly research potential cohabitants before introduction to ensure a serene and balanced aquatic environment.

Spatial Considerations:

To foster a peaceful coexistence, ensure the aquarium offers abundant cover and multiple hiding spots, breaking direct lines of sight. This enables multiple males to reside harmoniously in one setting. Nonetheless, for breeding objectives, it’s prudent to segregate pairs, creating a conducive environment for propagation.

In summary, while Betta siamorientalis might present specific cohabitation challenges, with mindful planning and understanding of their nature, a tranquil and visually striking aquarium is well within reach.


In the intricate ballet of Betta siamorientalis reproduction, certain nuances are pivotal for success:

Preparing the Breeding Ground:

The Betta siamorientalis, a bubble-nester by nature, demands a meticulous set-up for its reproductive dance. If not already in solitude, ensure a distinct breeding tank, aligned with earlier suggestions. Paramount to this is a perfectly sealed cover — some enthusiasts even resort to clingfilm — as the emerging fry crucially need access to a layer of warm, humid air. Without it, the labyrinth organ’s development could be compromised.

Courtship and Nesting:

While separation isn’t mandatory pre-spawning, the male exhibits a territorial streak, crafting his nest undisturbed, be it within a tube, beneath expansive plant leaves, or amidst surface vegetation. Only once this sanctuary is complete does he tolerate the female’s proximity. As spawning nears, the female undergoes a subtle transformation, her hue lightening and dark flanks becoming prominent. Their union unfolds beneath this nest in an osphronemid-typical ’embrace’. With the male enveloping her, they release milt and eggs in synchrony. The female, in a maternal dance, collects any fallen eggs, passing them to the male for safekeeping within the nest. This ritual continues until she is devoid of eggs.

Post-Spawning Care:

Upon spawning, the male assumes guardianship of the nest, with the female’s role culminating. As the eggs blossom into life between 24-48 hours, they remain ensconced in the nest for an additional few days, nourishing from their yolk sacs. The ever-vigilant male keeps collecting any straying offspring. If danger looms, he may even relocate the entire nest. Once the fry start exploring freely, his protective interest wanes. Yet, unlike some species, the Betta siamorientalis adults usually resist the instinct to prey on their offspring.

Feeding the Young:

The nascent fry thrive on an infusoria-rich diet in their initial days, gradually graduating to microworm and Artemia nauplii. However, a word of caution: overindulgence in Artemia nauplii has been linked to health concerns in Betta juveniles. For an ideal growth trajectory, diversify their diet, feeding them small portions 2-3 times daily. Additionally, regular, incremental water changes are more beneficial than sporadic, substantial shifts.

In summary, while the reproductive journey of Betta siamorientalis is a delicate dance, with precise care and attention, it unfolds into a mesmerising spectacle of life.

Betta siamorientalis: A Tapestry of Fascinating Facts

The Betta siamorientalis, a gem amongst aquatic aficionados, presents a myriad of intriguing facets. Native to the freshwater realms of Thailand, Cambodia, and Vietnam, its distribution is commendably expansive, revealing the species’ adaptability. Characteristically, it seeks refuge within submerged vegetation, crafting bubble nests – a unique reproductive strategy amongst its ilk. Its morphological attributes, from its slender form adorned with iridescent scales to its nuanced colouration, paint a portrait of nature’s finesse. In captivity, while it welcomes a diverse diet, it exhibits a notable propensity towards obesity, necessitating vigilant feeding. Notably, unlike many of its Betta relatives, the siamorientalis, in a twist of parental compassion, abstains from preying on its own fry. This species, undoubtedly, is a confluence of nature’s marvels and mysteries, making it a captivating subject for both researchers and hobbyists.

In Retrospect: The Enigma of Betta siamorientalis

In the intricate tapestry of the aquatic world, the Betta siamorientalis emerges as a standout character, captivating the hearts of enthusiasts and researchers alike. From its extensive distribution across Southeast Asia’s freshwater habitats to its singular morphological splendour, this species encapsulates nature’s boundless creativity. Its nuanced dietary preferences, reproductive strategies, and congenial disposition further punctuate its uniqueness. As with all treasures of the natural world, understanding and preserving the Betta siamorientalis requires both passion and responsibility. For those fortunate enough to delve into its world, it offers endless wonder and insight, exemplifying the profound connections we share with the natural realm.