Betta imbellis
Etymology
Betta: from ikan betah, the vernacular Malay for species of this genus.
imbellis: from the Latin imbellis, meaning ‘peaceful’.
Distribution
Thought to occur naturally in southern (peninsular) Thailand, Peninsular Malaysia, and northern Sumatra, but has been introduced to other areas with feral populations now established in Singapore, for example.
Type locality is ‘wetlands in the area surrounding Kuala Lumpur, Malaysia’.
Habitat
Inhabits still and sluggish waters, including rice paddies, swamps, roadside ditches, streams and ponds. These are often shaded by submerged, surface or marginal vegetation and sometimes contain little dissolved oxygen. Water conditions tend to vary and change rapidly during the annual monsoon season. Substrates can vary from leaf litter to mud, sand, or deep sediment. While most populations occur in freshwater some are found in brackish coastal swamps.
Introduction of ornamental forms and other Betta spp. such as B. splendens is known to be having an adverse effect on the genetic integrity of some wild populations.
Maximum Standard Length
50 – 60 mm.
Aquarium Size
An aquarium with base measurements of 45 ∗ 30 cm or equivalent is large enough for a pair.
Maintenance
This species fares best in a well-planted, shady aquarium with plenty of surface cover in the form of tall stem plants, floating types such as Salvinia or Riccia spp., or tropical lilies from the genus Nymphaea. Cryptocoryne spp. are also a good choice.
Driftwood can also be used and other plants such as Microsorum or Taxiphyllum spp. may be attached to it. Small clay plant pots, lengths of plastic piping or empty camera film cases can also be included to provide further shelter.
The addition of dried leaf litter offers additional cover and brings with it the growth of microbe colonies as decomposition occurs. These can provide a valuable secondary food source for fry, while tannins and other chemicals released by the decaying leaves are considered beneficial.
As it naturally inhabits sluggish environments strong water movement should be avoided, with an air-powered sponge filter set to turn over gently adequate. Keep the aquarium well-covered and do not fill it to the top since like all Betta spp. it requires occasional access to the layer of humid air that will form above the water surface, and is an excellent jumper.
Water Conditions
Temperature: 20 – 28 °C
pH: 5.0 – 7.5
Hardness: 18 – 179 ppm
Diet
Likely to prey on aquatic and terrestrial invertebrates in nature.
Captive fish will normally accept dried products once they are recognised as edible, but should be offered plenty of small live or frozen foods such as Daphnia, Artemia or chironomid larvae (bloodworm) regularly to ensure development of optimal colour and condition.
Take care not to overfeed as Betta spp. seem particularly prone to obesity.
Behaviour and Compatibility
Not recommended for the standard community aquarium. Its care requirements and disposition mean it is best kept alone or with very peaceful species. Some small cyprinids and loaches that inhabit similar environments in nature are suitable, but proper research prior to purchase is essential and in most cases it is best maintained alone.
Provided there is sufficient cover it is possible to keep more than one male per tank, though it is considered best practice to isolate pairs for breeding purposes.
Sexual Dimorphism
Males are more colourful than females and develop extended fins as they mature.
