Betta simplex

Osphronemidae. Subfamily: Macropodusinae

This species is endemic to a series of pools plus a small stream draining them in the southern province of Krabi, Thailand. Unfortunately due to this extremely restricted range plus the fact that the wild fish are being regularly collected for the aquarium trade it is threatend by extinction. The IUCN Red List of Threatened Species currently lists its status as "vulnerable", although the last official assessment was carried out in 1996 so conceivably the situation may have worsened since then.

Unusually for a Betta its habitat is located in a karstic (limestone) area and thus contains neutral to alkaline water (pH 7.0 - 7.4). It consists of a series of deep limestone sinkholes forming pools at the surface, plus a small ditch which acts as an overflow from the pools. The water is very clear and is tinted a bright blue/green colour due to reflection of light from the high levels of calcium carbonate it contains. According to the reports we've read the Betta are most abundant in the small drainage ditch leading off the pools. This often drys out to quite a large extent, some of the fish managing to survive in shallow puddles for part of the year. Marginal vegetation grows quire densely around the ditch although aquatic vegetation is mainly confined to the pools, where large beds of Cryptocoryne cordata flourish.

Around 2"/5cm.

An 18" x 12" x 12"/45cm x 30cm x 30cm/42.5 litre tank could easily house a pair of these. While some breeders maintain it in smaller tanks we prefer to see the fish in more spacious surroundings. If you want to keep a group correspondingly larger housing will be required.

This species does best in a well-planted, shady tank with plenty of surface cover in the form of tall stem plants (Hygrophila corymbosa is a good choice and is dead easy to grow), floating species such as Salvinia or Riccia or perhaps tropical lilies of the genus Nymphaea. Lower down the tank Cryptocorynes are a good choice and will cope with the dimmer conditions. The addition of a few driftwood roots and branches can also add to the natural feel, and will provide further hiding places for the fish. 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. To these can be attached other plants that thrive under low lighting such as such as Microsorum pteropus, Taxiphyllum barbieri or African Anubias. Small clay plant pots, lengths of plastic piping or empty camera film cases can also be included to provide further shelter.

Whilst this species does not require tannin-stained water a couple of handfuls of dried leaf litter (beech, oak or Ketapang almond leaves are all suitable; or indeed a mixture of all three) would not be disrepresentative. In addition to offering further cover for the fish the leaves would also bring with them the growth of microbe colonies as decomposition occurs. 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.

As the species hails from sluggish waters, filtration should not be too strong. An air-powered sponge filter set to turn over slowly is adequate, or if using a power filter adjust it to the lowest flow setting. Keep the tank well-covered and do not fill it to the top as like all Betta it requires access to a layer of humid air above the water surface and is an excellent jumper.

71 - 77°F/22 - 25°C

7.0 - 8.0. This species will not do well in acidic water.

The water at the type locality was recorded at 11°H. In the aquarium the fish should be happy provided it does not fall below 5° or so.

In nature it is known to prey on small insects and various zooplankton, but captive specimens will normally accept dried foods once they are recognised as such. Like all fish it does best when offered a varied diet. In this case regular meals of live or frozen foods such as Daphnia, Artemia or bloodworm should ensure the development of the best colours and condition. 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.

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, small species. When kept alongside bigger or more vigorous tankmates it can be outcompeted for food and may become shy and withdrawn. Potential options include dwarf Corydoras, Otocinclus, and small cyprinids such as Trigonostigma or Boraras. Most experts agree that this species is best maintained alone as successful breeding ought to be a priority for any hobbyist lucky enough to be keeping a beautiful, endangered species such as this.

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.

As it's a paternal mouthbrooder the head of the male is noticeably larger than that of the female. Males are also the more colourful sex when mature, possessing a larger amount of iridescent scaling and colourful patterning in the unpaired fins.

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.

Betta simplex is included in the Betta picta  complex of closely-related species, an assemblage which also includes B. falx , B. pallida, B. taeniata  and of course B. picta . It is one of the more commonly seen member of the group in aquarium circles and is a good choice for those new to "wild-type" Betta species as its upkeep and breeding are quite simple when compared with many members of the genus.

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

1. Tan, H.H. and P.K.L. Ng. - Raffles Bull. Zool. Supplement (13):43-99. 2005
   The fighting fishes (Teleostei: Osphronemidae: Genus Betta) of Singapore, Malaysia and Brunei.
2. Schindler, I. and J. Schmidt. - Zeitschrift für Fischkunde vol.8(1/2): 47-69. 2006
   Review of the mouthbrooding Betta (Teleostei, Osphronemidae) from Thailand, with descriptions of two new species.
3. www.siamensis.org
4. www.fishbase.org
5. www.ibcbettas.org
6. www.siamensis.org