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| Betta Raja |
Male of Betta raja.
Osphronemidae. Subfamily: Macropodusinae
Distribution
Endemic to parts of the island of Sumatra, Indonesia. The
type specimens were collected from a stream named Ayer Merah which is a
tributary of the Danau Arang Arang in the province of Jambi. The species has
also been collected from various localities in the provinces of Riau (river
Indragiri basin), Sumatra Selatan (in the north of the province) and Sumatra
Barat (in the eastern regency of Sawahlunto Sijunjung). Populations from the
different localities should ideally be labelled as such by collectors/enthusiasts
in order to maintain accuracy and preserve pure bloodlines.
Habitat
According to the official description this species is found
in lowland forest swamps. A particular blackwater lake is also mentioned as a
specific biotope but we also know of collections having occured in clearwater
environments. Presumably it prefers the type of habitat favoured by most other
Betta species ie. shaded, quiet waters where overhanging/marginal vegetation
grows thickly although it appears that the species is quite adaptable to
differing water parameters.
Maximum Standard Length
A fully-grown male can measure in excess of 4"/10cm.
Minimum Tank Size
A 30" x 12" x 12"/76cm x 30cm x 30cm/70.8
litre tank could comfortably house a pair or small group of these.
Tank Setup
This species can be maintained in a well-planted aquarium,
but most breeders use bare-bottomed tanks. You can add a thin layer of sand or
gravel if you prefer. Add a few driftwood roots and branches, placing these in
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 (beech or oak is probably
best as the popular Ketapang almond leaves tend to leach a lot of tannins which
may have an adverse effect on this clearwater species) could further emphasise
the natural feel, as well as offering a little extra cover. The tannins and
other chemicals released by the decaying leaves are thought to be beneficial
for the fish and the growth of microbe colonies will occur. These tiny
creatures can provide a valuable secondary food source for fry. Leaves can be
left in the tank to break down fully or removed and replaced every few weeks.
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 Cryptocorynes. A few patches of floating vegetation would be really
useful to diffuse the light entering the tank too. Also keep the tank
well-covered and do not fill it to the top as like all Anabantoids it requires
access to a layer of humid air above the water surface and members of this
genus are typically excellent jumpers.
Temperature
71.5 - 81°F/22 - 27°C
pH Range
If you are keeping wild specimens try to find out the
collection locality as some populations do best in particularly acidic/alkaline
conditions. Tank-bred fish tend to be quite adaptable and should be happy
within the pH range 5.5 - 7.0. We've even read reports of them breeding in
alkaline water.
Hardness
Generally prefers soft water of 5 - 10°H but tank-bred fish
have been spawned in water with a GH of up to 20°H.
Diet
In nature it probably eats insects and other invertebrates,
with smaller fish perhaps being preyed upon as well. It will normally accept
dried foods once they are recognised as such, but like all fish does best when
offered a varied diet. In this case regular meals of live or frozen foods such
as Daphnia, Artemia or bloodworm will ensure the development of the best
colours and condition. Small insects such as crickets or Drosophila fruit flies
are also suitable to use; it's best to fill the stomachs of these by feeding
them fish flakes or some kind of vegetable matter before offering them to the
fish. Take care not to overfeed as Betta species seem particularly prone to
obesity. Some experts have also warned of health problems developing when
they're fed excessive quantities of Artemia, especially in young fish.
Compatibility
Not a recommended choice 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. Tankmates small enough to
be eaten are liable to end up on the menu while much bigger or more vigorous
fish are likely to intimidate this Betta. Some of the medium-sized rasborines
and barbs are suitable though, and it can even be maintained alongside other
Anabantoids given sufficient space.
Provided the tank contains plenty of hiding places and
broken lines of sight there's no reason why a group of these cannot be
maintained together. Although a little squabbling is inevitable (especially
between males) it is generally quite a peaceful species.
Sexual Dimorphism
Males tend to grow larger than females and develop extended
fins as they mature. The head profile in males is also noticeably stockier than
that of females, presumably because it is the male that mouthbroods eggs and
fry.
Breeding
By all accounts this species isn't too difficult to breed if
the fish are provided with the correct water conditions and diet. You'll need
to organise a separate tank for the purpose unless they 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
this the development of the labyrinth organ can be impaired.
A single pair or group of fish can be used, and feeding a
varied diet containing plenty of live and frozen foods should bring them into
spawning condition. It is the female that plays the more active role in both
initiating courtship and defending the area against intruders. Eggs and sperm
are released during a typical Anabantoid embrace in which the male wraps his
body around that of the female. Several "practice" embraces may be
observed before any eggs are released and in some cases several days may pass
before a genuine spawning event is seen.
Eggs are laid in small batches and are picked up in the
mouth of the female before being spat out into the water for the male to catch.
This process can take some time, sometimes with the pair even continuing to embrace
before the female has got rid of all the eggs in her mouth. They are always
collected again if the male misses them though.
Post-spawning it is very important to give the male as much
peace and quiet as possible as the chances of him swallowing the eggs increase
if he is unduly disturbed. For this reason many breeders leave the female in
situ as apparently she will not harass the male while he is brooding whereas
netting her from the tank may stress the male. The male will tend to seek a
hidden or shaded spot and will lose much of his colour during the incubation
period. Others swear by removing the female post-spawning so it may be a case
of experimenting to find which method works best for you.
The incubation period is around 9 - 16 days. This would seem
to be at least partly temperature-dependant. When ready the male will release
fully-formed fry from his mouth. Once the fry are free swimming you may wish to
remove the male as if the female attempts to spawn with him again too soon he
may starve to death. Giving the male a recovery period and plenty of good food
post-brooding is highly recommended by some breeders while others simply keep
the pair together constantly. Some keepers also leave both parents in with the
fry and they are said not to harm them. Others remove the adults or fry and
raise the young separately.
The fry are big enough to accept motile foods such as
microworm and/or Artemia nauplii (see above notes on the feeding of Artemia to
young Betta) immediately. Feed them small amounts of different foods 2 -3 times
per day for the best rate of growth. Small (5 - 10% of tank volume) daily water
changes can also be introduced to prevent organic wastes accumulating.
Notes
Betta raja is included in the Betta pugnax complex of closely-related species, an
assemblage which also currently includes B. breviobesus, B. cracens , B. enisae
, B. fusca, B. lehi , B. prima , B. pulchra, B. schalleri, B. stigmosa and of course B. pugnax . Two Thai species described
by Schindler & Schmidt in 2006, B. apollon and B. ferox are also (albeit
tentatively) included in the group although these are not recognised as valid
by all authorities (the pair are omitted from Fishbase at time of writing, for
example). The pugnax group occupies a particularly enigmatic position within
the hobby due to the fact they are notoriously difficult to identify correctly
due to a lack of definitive scientific information on the member species. In
their 2005 paper covering the Labyrinths of Sumatra Tan and Ng described the main
morphological factors distinguishing Betta raja from the rest of the group
thus:
"mature males with very long pelvic fin (15-23 anal fin
rays at pelvic fin end, even exceeding anal-fin base in some specimens); more
anal fin rays than B. fusca (25-28, vs. 24-25); fewer anal fin rays than B.
schalleri (mode 26, vs. 27); fewer dorsal fin rays than B. pugnax , B.
schalleri and B. prima (mode 9, vs.
10-11); more subdorsal scales than B. enisae
(6-7, vs. 5-5.5); more lateral scales than B. fusca, B. prima and B. enisae
(30-32, vs. 26-29); fewer lateral scales than B. cracens (mode 31, vs. 33); more predorsal scales than
B. schalleri (20-22, vs. 17-19); fewer predorsal scales than B. cracens (20-22, vs. 23-24); smaller postdorsal length
than B. prima (20.0-24.6% SL, vs.
24.1-26.3); greater head length than B. fusca and B. cracens (33.9-37.4% SL, vs. 30.8-33.8; 50.4-55.7%
predorsal length, vs. 46.3-49.4); greater body depth at dorsal-fin origin than
B. schalleri, B. enisae and B.
cracens (28.1-33.5% SL, vs. 21.2-28.9);
greater caudal peduncle depth than B. cracens
(18.3-23.2% SL, vs. 15.1-16.7); greater preanal length than B.
cracens (42.0-46.1% SL, vs. 46.1-52.4);
greater pelvic fin length than B. prima
(37.4-69.8% SL, vs. 30.1-37.2; greater dorsal-fin base length than B.
enisae (37.4-69.8% SL, vs. 8.7-12.1);
slightly smaller head width than B. fusca (51.8-62.0% HL, vs. 59.7-69.8);
greater snout length than B. cracens
(26.3-29.8% HL, vs. 24.0-25.8); smaller orbital diameter than B.
pugnax (24.0-28.7% HL, vs. 27.9-38.5)
and B. schalleri (46-64% postorbital length, 61-76)."
Additionally, despite Betta raja only being described in
2005 it has been exported to the aquarium trade for at least a decade as B.
fusca (along with B. pugnax ). It is more than likely that the majority of
"B. fusca" currently in the hobby are actually Betta raja. This had
led to some experts speculating as to whether B. fusca is even a valid species,
whilst others have suggested that its live colouration/patterning should be considered
unknown pending further study.
All species in the suborder Anabantoidei possess an
accessory breathing organ known as the labyrinth organ. So-called due to its
maze-like structure, this organ allows the fish to breathe atmospheric air to a
certain extent. It is formed by a modification of the first gill arch, and
consists of many highly vascularised, folded flaps of skin. The structure of
the organ varies in complexity between species, tending to be more
well-developed in those inhabiting particularly oxygen-deprived conditions.
Literature cited
Tan, H.H. and P.K.L. Ng. - Raffles Bull. Zool. Supplement
(13):115-138. 2005
The labyrinth fishes (Teleostei: Anabantoidei, Channoidei)
of Sumatra, Indonesia.
source
www.fishbase.org
www.seriouslyfish.com
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