Siamese Fighting Fish
Siamese Fighting Fish

Siamese Fighter

Betta splendens
DistributionNative to Cambodia, Laos, Thailand and Vietnam. Introduced to many other countries.
Sexual DimorphismMales have elaborate finnage and are often much more colourful.
Maximum Size6.5cm (2.6”)
Water ParametersWill acclimatise to a wide range of conditions. pH: 6.0-7.5, dH: up to 20 degrees.
Temperature24-30 deg C (75-86 deg F)
CompatibilitySpecialist Community
LightingNo special requirements

The brilliantly coloured long-finned varieties of the Siamese Fighting Fish seen in many shops today have been developed over the years by captive breeding projects. Indeed, the natural wild colouration for this species is actually quite a dull green/brown, with relatively short finnage. Many strains, such as the Longtail, Shortail, Crowntail, Half Moon and Double Tail, and various colour types including red, blue, green, white, golden, black, marble, and many others, have been developed and are now available to the hobbyist. Siamese Fighting Fish, although capable of breathing atmospheric air via their labyrinth organ, must always be housed in filtered aquaria. Small vases and bowls are not suitable and are considered most cruel. These fish deserve proper stable water conditions and temperatures, as does any fish in our care, and this can only be achieved in a closed system by use of a heater/thermostat, a filter and regular partial water changes. Male Siamese Fighters should never be housed with other males, as territorial battles will break out immediately. As these attacks can be very violent and stressful to the fish, the loser will invariably end up becoming weakened and if not separated from the other, it is likely to be pursued until it is killed. It is wise, therefore, to take your time to find yourself the male of your choice and keep him as a lone specimen. Females of the species often display slightly more muted colours and generally possess much shorter finnage. It should never be assumed that a male and female can be housed together within the confines of the same tank. Females themselves can also be surprisingly aggressive, and if conditions are not exactly right for breeding, the male will attack her. If you wish to add a female, the best way to introduce her is by use of a divider, so that the pair can see each other but not physically get at each other. If, after a few days of the male and female fish observing each other there appears to be no confrontational displays, you can try removing the divider. Be sure to observe them for some time after removing the divider in case the fish are not compatible and it needs to be put back again. More than one female can be kept together, although the group must consist of at least 5 individuals. Smaller groups of females will result in the Alpha fish (the one at the top of the pecking order) picking on the subordinate females. In larger groups, any aggression will be spread amongst the group, rather than just one or two fish bearing the brunt. It is not advisable to house male and females together permanently, instead this is best carried out only when spawning is being attempted (see below). An aquarium containing just female Siamese Fighters without male company, but along with other compatible community fish, actually makes for a very beautiful sight. The aquarium itself should be at least 24” long and contain a maze of heavy planting (both rooted and floating specimens). Although these fish will adapt to a wide range of conditions, they will be seen at their best in soft, slightly acidic water (peat filtration suggested). The filter should provide a gentle water circulation in order to mimic the natural conditions where this species originates from: rice paddies, floodplains and other slow-moving waters. As mentioned above, Siamese Fighting Fish have the ability to take in warm air from above the water’s surface, so a small gap must be left between the surface of the water and the cover slides in order for the fish to accomplish this. Tankmates should be relatively small (although not too tiny or they may be mistaken for a snack), peaceful and not prone to nipping fins. Male Guppies should be avoided, as the male Siamese Fighter may well mistake their ornate finnage for that of another male Siamese Fighter.


Small frozen foods such as bloodworm, white mosquito larvae, vitamin-enriched brineshrimp, daphnia etc. Will also take flake and ‘Betta formulas’ from the surface of the water.


The first difficulty is in obtaining a compatible pair, as not all males and females will be suited. A separate well-planted breeding aquarium should be used, along with a divider so that male and female can be kept separate until you are happy that they appear compatible. If not, you may have to try again on another occasion with a different female. The second important point is to ensure you have adequate time to observe the spawning process, as the female cannot be left alone in the tank with the male once the process is complete. If all goes to plan, the male will build a bubble-nest at the water’s surface amongst floating plant cover, and entice the female underneath it. As the eggs are expelled and fertilised, the male catches any that stray and places them in the safety of the bubble-nest. Once spawning is over, the female must be removed immediately or the male may end up killing her in his defence of the egg-laden nest. These eggs should begin to hatch in 24-36 hours and the fry are usually free-swimming 3-5 days later, at which time they may be offered tiny foods such as infusoria. It is of extreme importance to maintain a warm layer of air between the surface of the water and the coverslides at all times whilst the fry are developing their labyrinth organ, critical during the first few weeks of their life.

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