simorum: named for Thomas G. K. Sim and his wife Farah, proprietors of Sindo Aquarium Pte. Ltd. ‘for being such excellent hosts during our stays in Jambi’.
This species has been collected from various localities in the province of Jambi, Sumatra, the adjacent province of Riau, and the Kapuas River system in Kalimantan Barat (West Kalimantan) province, Borneo.
The type specimens were collected from ‘Swamp in Rantau Panjang, Jambi Province, Sumatra, Indonesia’, not to be confused with the town of the same name on the Thai-Malay border, whilst in Riau the species appears restricted to the Indragiri river basin.
Populations from different localities are often labelled as such by collectors and enthusiasts in order to maintain accuracy and preserve pure bloodlines, e.g., Rantau Panjang, Pematang Lumut (both in Jambi), Sungai Bengkwan (Riau), etc.
Inhabits heavily-vegetated forest peat swamps and associated black water streams.
These ancient biotopes are usually found in areas of rainforest, the dense canopy of branches above meaning very little light penetrates the water surface with riparianvegetation tending to grow thickly.
The water is typically stained darkly with humic acids and other chemicals released by decaying organic material.
The dissolved mineral content is generally negligible and the pH can be as low as 3.0 or 4.0.
The substrate is usually covered by fallen leaves, branches and submerged tree roots and at certain times of year the fish may be forced to survive within the moist leaf litter for several weeks as permanent water is not always available.
80 – 90 mm.
Can be maintained in a fully-decorated aquarium although many breeders prefer not to use a substrate for ease of maintenance.
Driftwood roots and branches can be used and placed such a way that a few shady spots are formed while clay plant pots or lengths of piping can also be included to provide further shelter.
The addition of dried leaf litter further emphasises the natural feel and as well as offering additional cover for the fish brings with it the growth of microbe colonies as decomposition occurs.
These can provide a valuable secondary food source for fry and the tannins and other chemicals released by the decaying leaves are also considered beneficial for fishes from blackwater environments.
There is no need to use natural peat, however, the collection of which is both unsustainable and environmentally-destructive.
Like others in the genus this species seems to do best under fairly dim lighting.
You could add aquatic plant species that can survive under such conditions such as Microsorum, Taxiphyllum or Cryptocoryne spp., and a few patches of floating vegetation would be useful as well.
This species requires acidic conditions with negligible carbonate hardness and very low general hardness so a reverse osmosis unit or other method of obtaining soft water may need to be employed, and this can be further acidified using phosphoric acid or similar if necessary.
As it naturally inhabits sluggish waters filtration should not be too strong, with an air-powered sponge filter set to turn over gently adequate.
Keep the tank well-covered and do not fill it to the top as 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.
Temperature: 25 – 30 °C
pH: 3.0 – 6.0
Hardness: 18 – 90 ppm
A study conducted in 1994 (in which the species was considered to be B. bellica) revealed a preference for odonate (dragon and damselfly) nymphs, although it probably predates on other small invertebrates as well.
Like B. bellica it’s a prodigious jumper and has been observed to leap from the water to catch prey from overhanging leaves or branches.
In captivity it will normally accept dried foods once they’re recognised as edible, but should be offered small live or frozen foods such as Daphnia, Artemia or bloodworm regularly to ensure development of optimal colour and condition.
Take care not to overfeed as Betta spp. seem particularly prone to obesity.
Mature males are more intensely-coloured and develop slightly more extended fins than females.