The Siamese fighting fish (Betta splendens), also known as the betta fish or just betta, is one of the most popular species of freshwater aquarium fish. It is native to the rice paddies of Thailand and called pla-kad or pla-kat ("Biting Fish") in its native Thailand.

The name Betta (or betta) is

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.[1] That is, the first part is the same as the English word bet. By confusion with the name of the Greek letter beta, the name is often pronounced Template:IPA in American English, and may be misspelled with one t. The name of the genus is unrelated to that of the Greek letter, being derived from ikan bettah, in a local language in Thailand.[2]

Siamese fighting fish usually grow to an overall length of about Template:Convert, though some varieties reach Template:Convert in length. In recent years when breeders have been able to create "Siamese fighting fish" that exceed Template:Convert due to the manipulation of a mutant gene. Although Siamese fighting fish are known for their brilliant colors and large, flowing fins, the natural coloration of Siamese fighting fish is a dull green and brown, and the fins of wild specimens are relatively short. However, brilliantly colored and longer tail-finned varieties, such as veil tail, delta, super delta, and half moon have been developed through selective breeding.

The Siamese fighting fish is a member of the Gourami family (family Osphronemidae) of order Perciformes, but was formerly classified among the Anabantidae. Although there are nearly 50 other types of Siamese fighting fish, Siamese fighting fish is the most popular species among aquarium hobbyists, particularly in the United States.


Like anabantids and all members of the genus Betta, Siamese fighting fish have a labyrinth organ in their heads that allows them to take oxygen directly from the atmosphere in addition to the oxygen taken from water with their gills. Siamese fighting fish that cannot reach the surface may drown.


Siamese fighting fish have upturned mouths and are primarily carnivorous surface feeders. In the wild, Siamese fighting fish feed on zooplankton and the larvae of mosquitoes and other insects, such as flies, crickets, or grasshoppers.Template:Fact Bettas which feed on wide range of foods live longer, have richer colors, and heal fin damage more quickly. Typically, Betta pellets are a combination of mashed shrimp meal, fish meal, brine shrimp, blood worms, and vitamins. Siamese fighting fish also will eat live or frozen blood worms, brine shrimp or daphnia. For variety and fiber, Siamese fighting fish are fed finely-chopped, high-protein vegetables, such as soybeans, green beans, broccoli, corn, and carrots. Some Siamese fighting fish subsist on dried flaked food suitable for tropical fish, because although this feed reduces their coloring, the Siamese fighting fish are able to digest this better than pellets. However, feeding Siamese fighting fish with vegetables only is not a good idea since they are extremely carnivorous and do better with meat products. Siamese fighting fish can get constipated when their diet lacks variety. If their stomach looks swollen, feed them food with fiber.

Reproduction and nestsEdit

The Siamese fighting fish mate in a fashion that is called "nuptial embrace", in which the male and female spiral around each other, around 10-41 eggs are released and fertilized at each embrace, until the female is exhausted of eggs. The male carefully keeps every egg in his bubble nest, making sure none fall to the ground, and repairing the bubble nest as needed. Incubation last 30-40 hours, and the eggs hatch in 3-4 days.

Male Siamese fighting fish build bubble nests of various sizes and thicknesses at the surface of the water. During and after spawning, the male uses his mouth to retrieve sinking eggs and deposit them in the bubble nest. After approximately two days the eggs hatch, and after three more they become free-swimming fry; at this point the male is generally removed from the breeding tank to prevent eating the young. Betta fry are fed infusoria for the first several days, followed by newly hatched brine shrimp or similarly sized food.[3]

B. splendens can be hybridized with B. imbellis, Betta sp. Mahachai and B. smaragdina, though with the latter the fry tend to have low survival rates.


File:Betta splendens pale.jpg

Bettas have been affectionately nicknamed "The Jewel of the Orient" due to the wide range of colors which are produced through selective breeding.

Wild Siamese fighting fish only exhibit strong colors when agitated.Template:Fact However, breeders have been able to make this coloration permanent, and a wide variety of hues breed true. Siamese fighting fish come in a variety of colors, such as red, blue, turquoise, orange, yellow, white, and green. Most are slightly iridescent, and can appear to change color with different lighting or viewing angle. Breeders have also developed different color patterns such as marble and butterfly, as well as metallic shades such as copper, gold, and opaque.Template:Fact

Breeders around the world continue to develop new varieties. Often, the male species are sold preferentially in stores because of their beauty, compared to the females. Recently, breeders have developed in females with the same range of colors previously only bred in males. However, females never develop fins as showy as males of the same type and are almost always more subdued in coloration.

Tail shapesEdit

File:Betta splendens male doubletail.jpg

Breeders have developed several different tail shapes:

  • Veil tail (non-symmetrical tail, only two rays)
  • Crown tail (highly frilled, extended spiny rays)
  • Comb tail (less extended version of the crown tail)
  • Half-moon (large tail fin that forms a 180-degree, or larger, half circle)
  • Short-finned fighting style (sometimes called "plakat")
  • Double-tail (the tail fin is split into two lobes and the dorsal fin is significantly elongated)
  • Delta tail (tail span is less than half-moon with sharp edges)
  • Fantail (a rounded delta tail)


File:Betta Fighting Reflection.JPG

Both male and female Bettas flare or "puff out" their gill covers (opercula) in order to appear more impressive, either to intimidate other rivals or as an act of courtship. Both females and males will display horizontal bars (unless they are too light a color for this to show) if stressed or frightened. Females often flare their gills at other females, especially when setting up a pecking order. Flirting fish behave similarly, with vertical instead of horizontal stripes indicating a willingness and readiness to breed. The Siamese fighting fish sometimes require a place to hide, even in the absence of threats. The Siamese fighting fish may set up a territory centered on a plant or rocky alcove, sometimes becoming highly possessive of it and aggressive toward trespassing rivals/enemies.

On average, males are more aggressive, though individual females, especially crown tails, demonstrate a wide range in level of aggression. The aggression of Siamese fighting fish has been studied by ethologists and comparative psychologists[4]. Bettas will even respond aggressively to their own reflections in a mirror; use of a mirror avoids the risk of physical damage inherent in actual conflict.Template:Fact

Tankmates Edit

Because of the aggressive nature of the Siamese fighting fish species, tank-mates must be carefully chosen:

Two or more males: Contrary to popular belief, male Siamese fighting fish do not fight to the death in the wild; when one fish has won the fight/battle, the loser escapes/retreats to safety. Template:Fact In an aquarium, however, there is no retreat/escape at all, so the victor fish continues attacking the loser, often resulting in the loser's death, therefore, hobbyists rarely house two or more male Siamese fighting fish in the same tank unless they are (a) separated by a partition, or (b) they are from the same batch of eggs and are immature.

A male and a female: In the wild, females stay clear of males, except during mating. When cohabiting in tanks, males might kill females, and are generally kept apart unless (a) they are juvenile siblings, (b) they are breeding, (c) there is a partition, or (d) the tank is large enough for the female to escape attack. Often, before breeding, breeders use a partitioned container to allow female display without risking harm by the male.

File:Female bettas in community tank.jpg

Two or more females: Siamese fighting fish are not schooling fish at all, but in a large aquarium with many hiding spaces, female Siamese fighting fish can cohabit with each other. When two females share a tank, one usually bullies, torments, teased, and harassed the other; however, four or more females will establish a hierarchy allowing pacifist co-existence. Nevertheless, females living in community must be monitored for aggressive females.

Compatible fish of other species: Hobbyists put Siamese fighting fish in tanks with other species after careful research and preparation. Common tank mates include platies (moons), corydoras catfish, and loaches. Females can share a tank with danios, tetras, barbs, and gouramis. Shrimp are popular tank-mates because, provided with sufficient natural plant cover, they keep the tank clean without causing stress to the bettas. Template:Fact

The success of a Siamese fighting fish in a community aquarium, however, is largely dependent on the particular Siamese fighting fish's level of aggressiveness. Whereas some Siamese fighting fish make wonderful community fish, particularly belligerent or skittish Siamese fighting fish are best housed alone.

Incompatible fish of other species:

  • Very small fish (smaller than one inch) may be eaten.
  • Fish with long, flowing fins may trigger aggression.
  • Slow-swimming fish, e.g. fancy guppies, will be unable to escape bullying, tormenting, harassing, and teasing.
  • Mollies tend to bite the fin or (if large enough) eat Siamese fighting fish.
  • Fish belonging to the same biological family as the Siamese fighting fish, such as Paradise Fish and gouramis, may attack or be attacked due to their relatively similar appearance and cross species aggression.
  • Goldfish are unsuitable tank-mates because of their great appetites, preference for cold water, and high excretion-rate. Like many tropical fish, Siamese fighting fish might harassed, bullied, teased and kill small, slow fancy goldfish; in return, goldfish have been known to bite a Siamese fighting fish's tail. Goldfish also are best suited to a colder water tank than the tropical Siamese fighting fish.

Living conditions Edit


Siamese fighting fish are often kept in extremely small containers, a practice which many breeders consider inhumane. This practice is due in part to practical considerations; few pet stores have the space or finances to display a large selection of male Siamese fighting fish except in small containers. However, many inexperienced fish keepers still continue to house them in small containers after purchase. A popular misconception is that wild Siamese fighting fish live in very small puddles, and thus are "happier" when kept in cramped conditions. In reality, like any other fish, Siamese fighting fish are healthier, more active and will often grow larger when they are kept in a roomy tank. Breeders typically recommend that there be at least Template:Convert for each Siamese fighting fish, but Template:Convert or more is preferred.

The Siamese fighting fish deserves their reputations as a hardy, low-maintenance breed and a good choice for rookie breeders. However, they still require appropriate conditions to survive and thrive. Since it is a tropical fish it does best when kept in a tank with a heater, however use of heaters is strongly discouraged in tanks under Template:Convert in size. The ideal temperature for a Siamese fighting fish is 78-80°F. Temperatures lower than Template:Convert render the fish lethargic and illness-prone. They are capable of jumping from tanks and thus must be kept in a tank with a cover; this cover must not be air-tight, however, as the Siamese fighting fish needs to be able to breathe from the surface (especially in a tank which lacks aeration).

Many novice breeders mistakes are perpetuated by their hardiness. Along with believing that cramped spaces are good for them, new owners often believe they can live for extended periods in foul water, or that a Siamese fighting fish doesn't require water changes. Siamese fighting fish in 1 gallon tanks require 2-3 water changes a week. Siamese fighting fish in Template:Convert tanks can make it with weekly water changes and maintain good health for many years.

These beautiful fish enjoy plastic plants and small ornaments they can rest on. Of course real plants are even better. Many Siamese fighting fish also like ornaments with small openings they can swim in and out of. However, especially with veil tails, plants and ornaments need to be free of sharp edges to prevent the fish from tearing their fins. Due to frequent water changes, most owners do not use the standard aquarium gravel, for fish tanks and bowls, instead using glass pebbles and/or marbles designed especially for aquariums.

Further readingEdit

  • Simpson, M. J. A. (1968). The display of the Siamese fighting fish Betta splendens. Animal Behaviour Monographs, 1, 1-73.
  • Thompson, T. (1966). Operant and Classically-Conditioned Aggressive Behavior in Siamese Fighting Fish. American Zoologist, 6, 629-741 (doi:10.1093/icb/6.4.629).

External LinksEdit

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