Siamese Fighting Fish (Bettas) are anabantoids, which means they can breathe atmospheric air thanks to a unique organ called the labyrinth. This accounts for their ability to thrive in low-oxygen water conditions that would kill most other fish, such as rice paddies, slow-moving streams, drainage ditches, and large puddles.
B. splendens grows to an overall length of approximately 6 cm (2.5 in), and has an average life span of four years. Well kept aquarium specimens have often lived well beyond six years. There are reports of captive Bettas living ten or more years in laboratory settings.
Under the right temperature range, (24-30?C) bettas are normally very active fish. They have good eyesight and will learn to surface for feeding time when a hand appears over the bowl and other simple recognition tools. During darker parts of the day, they may "sleep" or rest on the bottom of the tank or just under the surface where they can breathe. Bettas are very territorial and require a place to hide, even if there are no threats. They will cling very close to any plant or rocky alcove they can find, becoming highly possessive of it.
Because of the aggressive nature of this species, tankmates must be chosen carefully, and two male B. splendens should not be housed in the same tank unless they are separated by a dividing wall. As a general rule, male Bettas cannot be housed together. It is possible to house two male bettas in a single very large tank, provided that there is plenty of cover (such as floating plants) and enough space for both males to establish their own territories. However, this is an extremely risky procedure because of the male's natural territoriality. These experiments in housing males together often end in the death of one or both inhabitants of the tank. (Male bettas do not 'fight to the death' in the wild; once one fish has clearly won the encounter, the loser will retreat to a safe location. In an aquarium, however, there is no place to run, and the winning fish will continue to attack the loser, often ending in death.)
To maximize the lifespan of the fish and ensure their wellbeing, they should always be kept in appropriate sized tanks. As a rule of thumb, for each inch of fish there must be at least four liters of water in its tank. Bettas ideally should be kept in a filtered tank 40L or more and treated like any other freshwater tank fish. Although these conditions are ideal, with proper care and filtration a betta can be happily kept in a smaller tank.
Since bettas are from the rice paddies of southern Asia, they typically thrive in conditions somewhat similar to their origins. In the wild, the Siamese fighting fish inhabits standing or slow-moving water, including floodplains and rice paddies, at temperatures of 24 to 30 ?C. This level of temperature should be used in the aquarium. The pH level should range between 6.5 and 7 (slightly acidic).