Siamese fighting fish

(Click to enlarge)

Siamese fighting fish

Betta splendens male (top) and female Siamese fighting fish (Elizabeth Morales)

A small, often brightly colored, aggressive freshwater fish (Betta splendens) native to Malaysia and Thailand that has large fins and tail and is popular in home aquariums.

Betta splendens

FAMILY

Osphronemidae

TAXONOMY

Betta splendens Regan, 1910, Menam River [= Mae Nam Chao Phraya], Thailand.

OTHER COMMON NAMES

English: Betta; French: Combatant, combattant du Siam; German: Siamesischer Kampffisch; Spanish: Combatiente siamés.

PHYSICAL CHARACTERISTICS

Up to 2.4 in (6 cm). Elongate cylindrical body, dorsal fin short with one to two spines and seven to 10 soft rays. Anal fin is long with two to five spines and 21–26 soft rays, caudal fin rounded. First soft ray of pelvic fin elongated. Sexually dimorphic; males have larger fins and a brighter coloration, females less conspicuously colored. Wild type with bluish body and blue and red fins. Two vertical iridescent marks on the opercle. Some breeds with greatly enlarged fins (sail fin) and different colors or combinations thereof, some almost completely red, blue, yellow, or black.

DISTRIBUTION

The original distributional range comprises the Chao Phraya basin in Thailand and northernmost Malay Peninsula (north of Isthmus of Kra). The species has been transported and released in various countries in Southeast Asia, and can now be found even in the Dominican Republic, Colombia, Brazil, and Florida, in the United States.

HABITAT

Tolerates a wide range of water parameters. Common in stagnant or standing water bodies with dense aquatic vegetation, especially in rice paddies and in canals. May dig into the mud when the water recedes and survive weeks in a small cocoon-like structure made of mud and probably mucus.

BEHAVIOR

This species is well known for its prominently developed aggressive behavior, especially against conspecific males. Confined to small tanks, males fight until one of them is killed. In Thailand, various breeds of Betta splendens are used in popular fighting matches in which people bet on the outcome.

FEEDING ECOLOGY AND DIET

Carnivorous, feeding mostly on small aquatic invertebrates, such as zooplankton and insect larvae.

REPRODUCTIVE BIOLOGY

The male constructs a bubble nest and aggressively defends the territory around it. Has typical spawning clasp. After the spawning claps, male and female show spawning rigor, from which the male recovers earlier (after 4 s) than the female (after about 20 s). Up to 400 spherical eggs with a diameter of 0.04 in–0.05 in (1–1.4 mm) are laid per spawning sequence. They contain no oil globule and sink toward the bottom. While eggs are sinking they are collected by the male, later joined by the female, and stored in the nest. Hatching takes place after 32 to 35 hours at 84.2°F (29°C). Larvae swim free on the fourth day.

CONSERVATION STATUS

Not listed by the IUCN.

SIGNIFICANCE TO HUMANS

Very popular aquarium fish. Because of its hardy nature, often among the first species of freshwater fishes kept by beginners to the aquarium hobby. Of no interest to fisheries due to its small size.

(click to enlarge)
Siamese fighting fish (Betta splendens). (credit: Douglas Faulkner)

Freshwater tropical fish (Betta splendens; family Belontiidae or Anabantidae), noted for the males' pugnacity toward one another. A native of Thailand, it was domesticated there for use in contests. Combat consists mainly of fin nipping and is accompanied by a display of extended gill covers, spread fins, and intensified colouring. This slender fish grows to about 2.5 in. (6.5 cm) long. In the wild it is predominantly greenish or brown, with red fins; domesticated, it has been bred with long, flowing fins and in a variety of colours, such as red, green, blue, and lavender.

For more information on Siamese fighting fish, visit Britannica.com.