BETTA FISH; WILD HABITAT AND MORE:
The Siamese fighting fish; scientific name, Betta splendens.


I am writing this Aquarium Answers post/article to hopefully help with all the controversies around the internet and elsewhere about wild Betta habitat and requirements.
I would like to qualify this and state that as with many popular aquarium fish (such as Angels and Discus), the domestic versions are often adapted to the environment that they have been bred for, in other words, many angelfish although originally from low pH waters are now commonly bred in higher pH alkaline waters.
In the case of Bettas, these amazing fish come from a Tropical Habitat that is known fro drastic swings in water availability, clarity, parameters, and even temperature, this makes for a fish that is naturally uniquely adaptable to a variety of aquarium environments and is in part a reason for their popularity

River Drainage Basins and natural environment

The Chao Phraya River drainage is seen in the central Thailand area of the map while the Mekong River Drainage habitat is seen in Cambodia and Eastern Thailand

The Betta is native freshwater fish from Thailand (formerly Siam) and Cambodia (formerly Kampuchea). Most native Bettas originate from the Mekong AND the Chao Phraya River drainage basins. These drainages are mountainous with agriculturally
productive valleys found in the upper regions. The lower region contains alluvial plains that are highly productive for agriculture. The Mekong and Chao Phraya Rivers drains from north to south. Monsoon weather dominates, with a rainy season lasting from May to October and supplementary rain from occasional westward storm depressions originating in the Pacific. Temperatures range from15°C (59 F) in December to 40°C (104 F) in April except in high altitude locations. The basins can be classified as a tropical rainforest with high biodiversity. The lower parts have extensive irrigation networks and hence intensive rice paddy cultivation.
These rivers have a pH of 6.9 ranging to 8.2 and the nutrient level is low. In the Lower Mekong and Chao Phraya areas the river is turbid, especially during the rainy season.

With the very wide temperature swings it is easy to extrapolate that a betta can and will do well in a reasonable warm aquarium bowl environment that does not exceed the temperature extremes found in the wild, although this is not to say that a heated stable environment is not even betta for a healthy Betta (remember this IS a tropical fish).
The pH, GH, and KH also have wide swings, to which the Betta has adapted to, however keep in mind that rapid changes in pH can still harm or even kill a Betta and should be avoided. It is also note worth that the pH scale is logarithmic, so a full point change in pH is ten tenfold increase of decrease in pH. Please see this article for more about this subject: “The Importance of Calcium, GH, KH, Electrolytes, and pH in Aquariums”

The low water nutrient levels of these rivers lend themselves to a reducing Redox and lower nitrate levels, which means frequent water changes are important with bettas and if breeding on a large scale, a system in which the breeding sections are all linked to a central system with a UV Sterilizer is also useful for both disease prevention and Redox (but not essential). See this article for more about UV Sterilization: “How UV Sterilization Works in Aquariums and Ponds”

Being an anabantids, Bettas have a labyrinth organ in their heads that allows them to take oxygen directly from the atmosphere in addition to the oxygen taken from water via their gills which allows them to cope with the dry season in their monsoonal climate home.


All of the above environmental adaptation as well as breeding adaptation is why the Betta survives well in a small tank or even a bowl, but also make no mistake about it the Betta merely survives the dry season and its harsh realities of water quality, so providing your domestic Betta a heated, stable, regularly maintained tank, with proper electrolyte levels (even if under 2 gallons) will go a long ways in long term Betta health.

Although these beautiful fish were not seen in Europe until the 1800's, they have been cultured and kept in Thai households since the 1200's.
Bettas common aquariums have undergone centuries of selective breeding and have become far more aesthetically pleasing than the original Wild Betta, these “Domestic” bettas have also been adapted to the small aquarium environments in which they are often bred.
In the wild Bettas generally grow to 6.0 cm (2.3 in.), however many are now bred up to 8.0 cm (3.5 in.) in length. A Bettas diet in the wild generally consists of insect larvae such as mosquito larvae. It is noteworthy that many of these insect larvae feed themselves on green organic matter, so a proper diet should consist of food that duplicates the digestive contents of these larvae as well.












References
http://www.unesco.org/water/wwap/case_studies/chao_phraya/chao_phraya.pdf
http://internationalrivers.org/en/china/lancang-mekong-river

Further Reading

BC Aquatics; Betta FAQs