Betta rutilans
Etymology
rutilans: from the Latin participle rutilans, meaning ‘being red’.
Distribution
The species has been collected from localities connected with the rivers Mempawah and Kepayang close to the town of Anjungan in Kalimantan Barat (West Kalimantan) province, Borneo, Indonesia.
Type locality is ‘Sungei Kepayang, 7 kilometers southeast of Anjungan on road to Pontianak, 0°20’N, 109°08’E, Kalimantan Barat, Borneo’.
Habitat
A stenotypic inhabitant of peat swamp forests and associated black water streams.
The dense canopy of branches above means very little light penetrates the surface of such environments, and riparian vegetation also tends 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 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.
Maximum Standard Length
30 – 35 mm.
Aquarium Size
An aquarium with base measurements of 45 ∗ 30 cm should be the minimum considered.
Maintenance
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.
Water Conditions
Temperature: 22 – 27 °C
pH: 3.0 – 6.0
Hardness: 18 – 90 ppm
Diet
Likely to prey on insects and other small invertebrates in nature.
Captive fish will normally accept dried products once they’re recognised as edible, but should be offered plenty of small live or frozen foods such as Daphnia, Artemia or bloodworm regularly to ensure development of optimum 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 set-up for reasons already touched upon.
It’s care requirements and disposition mean it is best kept alone or with very peaceful species since much bigger or more vigorous fishes are likely to intimidate and outcompete it.
Some small cyprinids and loaches that inhabit similar environments in nature are suitable, but proper research prior to purchase is essential.
Mixed reports exist as to whether it can be maintained in multiple pairs or harem-type groups comprising a single male alongside several females.
Some observe that although some chasing and squabbling over territory occurs actual physical damage is rare, while others recommend keeping it in single pairs having observed sustained aggression towards conspecifics from the dominant individuals in a group.
Sexual Dimorphism
Mature females tend to be slightly rounder in the belly than males and exhibit slightly duller colouration.
Adult males also develop marginally more extended ventral, anal and dorsal fins.
