Betta cracens
Classification
Order: Perciformes Family: Osphronemidae
Distribution
The type specimens were collected from the area of Bertam south of Jambi City, Jambi province, Sumatra, Indonesia and it may also occur on Pulau Bangka (Bangka island). Bangka lies just of the east coast of Sumatra and fish collected there have appeared in the aquarium hobby as Betta sp. ‘Bangka’.
Habitat
The type locality is a stream in a forest swamp with dense growth of Barclaya motleyi at intervals, part of which had been turned over to cultivation of rubber trees in 1997.
The water depth varied between 5-80 cm, pH was 5.8 and syntopic species included ‘Puntius‘ banksi, Rasbora einthoveni, Trigonopoma pauciperforatum, Hemirhamphodon pogonognathus, Betta pugnax, Sphaerichthys osphromenoides, Trichogaster trichopterus, Channa gachua and C. lucius.
Betta sp. “Bangka” was collected from forest hill streams in clear water with a pH of 5.5. In photos we’ve seen of one locality the water appeared to be quite shallow with lots of leaf litter and fallen twigs.
Maximum Standard Length
55 – 60 mm.
Aquarium SizeTop ↑
An aquarium with base measurements of 80 ∗ 30 cm could house a pair or small group.
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.
If you can’t find driftwood of the desired shape common beech or oak is safe to use if thoroughly dried and stripped of bark. Clay plant pots or lengths of piping can also be included to provide further shelter.
The addition of dried leaf litter, with beech, oak or Ketapang almond leaves all suitable, can further emphasise 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.
Like others in the genus this species seems to do best under fairly dim lighting. You could add Asian plant species that can survive under such conditions such as Microsorum pteropus, Taxiphyllum barbieri or perhaps some potted Cryptocoryne spp., and a few patches of floating vegetation would be useful to diffuse the light entering the tank.
Filtration need 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: 5.5 – 6.5
Hardness: 0 – 90 ppm
Diet
Likely to prey on insects and other small invertebrates/zooplankton 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 optimal colour and condition. Take care not to overfeed as Betta spp. seem particularly prone to obesity.
Behaviour and CompatibilityTop ↑
Not recommended for the standard community set-up for reasons already touched upon. It’s requirements and disposition mean it’s 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 compatible.
It can be maintained in a pair or group and will display some interesting behavioural interactions under the latter circumstances.
Sexual Dimorphism
Males grow larger, possess a greater amount of iridescent scaling on the head, a broader head shape, and more extended fins than females.
Reproduction
Paternal mouthbrooder. Organise a separate tank for breeding purposes unless the fish are already being maintained alone, setting this up as suggested above.
The tank should have the tightest-fitting cover you can find (some breeders use clingfilm instead to ensure no gaps) as the fry need access to a layer of warm, humid air without which development of the labyrinth organ can be impaired.
The female plays the more active role in initiating courtship and defending the area against intruders. Eggs and milt are released during an ’embrace’ typical of anabantoids in which the male wraps his body around that of the female. Several ‘dummy’ embraces may be required before any eggs are released.
Once spawning commences eggs are laid in small batches and picked up in the mouth of the female before being spat out into the water for the male to catch. Once the male has all the eggs in his mouth the cycle is repeated untill the female is spent of eggs, a process which can take some time.
The incubation period is 12-18 days at the end of which the male will begin to release fully-formed, free-swimming fry. While some breeders have never had a problem with this species eating its own young others have lost entire broods through predation, but many remove the female (plus any other fishes present) a few days after spawning.
This needs to be done as carefully as possible in order to avoid disturbing the male as he may swallow or release the brood prematurely if stressed. Once the fry are swimming and foraging freely the male can also be removed if you wish.
The fry are large enough to accept motile foods such as microworm and Artemia nauplii immediately, though it should be noted that there exist reports of young Betta developing health issues if fed excessive amounts of the latter. Offer small amounts of different foods 2 -3 times per day for optimal growth rate, and don’t change too much water at once, with regular, small changes preferable.
NotesTop ↑
B. cracens is rare in the hobby with most of the fish being offered for sale under the name tending to be misidentified or intentionally mislabelled B. pugnax, B. raja, or other related species. It’s included in the B. pugnax complex of closely-related species within the genus, an assemblage of which members are notoriously difficult to identify.
The unique combination of characters distinguishing B. cracens from others in the group is as follows: most slender body among members (body depth at dorsal–fin origin 21.2-24.2% SL, vs. 24.8-36.9); anal-fin rays 27-29 vs. 24-27; lateral line scales 32-33 vs. 27-31; thin, blue distal margin on anal fin in both sexes; predorsal length 65.0-67.1 % SL; head length 30.8-31.7 % SL.
The genus Betta is the most speciose within the family Osphronemidae with almost 70 recognised members and looks set to grow further with new ones continuing to be described on a regular basis since the turn of the century.
Member species have successfully adapted to inhabit a variety of ecological niches from stagnant ditches to flowing hill streams including some extreme environments such as highly acidic peat swamp forests.
The referral of members to a number of groups containing closely-related species is now generally accepted but largely based on morphological/behavioural characters. Molecular phylogenetic work is thus required and would undoubtedly prove useful in more precisely determining relationships between these fishes.
A full list of the species groups as currently recognised can be found here.
Like others in the suborder Anabantoidei this species possesses an accessory breathing organ known as the labyrinth. So-called due to its maze-like structure this organ allows the fish to breathe atmospheric air to a certain extent.
Comprising paired suprabranchial organs formed via expansion of the epibranchial (upper) section of the first gill arch and housed in a chamber above the gills, it contains many highly-vascularised, folded flaps of skin which function as a large respiratory surface. Its structure varies in complexity between species, tending to be better-developed in those inhabiting harsher environments.
References
- Tan, H. H. and P. K. L. Ng, 2005 - Raffles Bulletin of Zoology Supplement 13: 115-138
The labyrinth fishes (Teleostei: Anabantoidei, Channoidei) of Sumatra, Indonesia. - Tan, H. H. and P. K. L. Ng, 2005 - Raffles Bulletin of Zoology Supplement 13: 43-99
The fighting fishes (Teleostei: Osphronemidae: Genus Betta) of Singapore, Malaysia and Brunei.
