Betta Splendens – commonly known as the betta or Siamese fighting fish.

Betta fish are known for their aggressive temperament, they are highly territorial and will fight viciously to protect their ground.

A solitary fish, Betta do not form schools as they will simply brawl with each other. If two male fish are kept together in the same tank, the fighting will never stop until one escapes or dies. Female betta fish are less aggressive but fighting will still occur if they are

Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Anabantiformes
Family: Osphronemidae
Genus: Betta
Species: B. splendens

Betta fish are native to the Mekong Basin of South-East Asia, an area spanning the three countries of Thailand, Vietnam and Cambodia and China.

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In Thai, the fish is called “pla-kad” (literally fighting-fish).

Just like goldfish, Betta fish in the wild usually have darker colors such as brown, grey and dull green. They have been bred in captivity to display more recessive traits such as red, blue and bright orange.

Other physical traits such as large and fancy tails are also selectively bred, they rarely occur in nature because they do not have an evolutionary advantage in the wild.

Just like everything else in the world, rarity beautiful, it is no co-incidence that humans like keeping things which rarely occur naturally, rare fish fetch far higher prices than common fish among aquarium enthusiasts worldwide.

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Although Betta fish are quite common in fishtanks around the world because they are relatively simple to keep and breed, their numbers in the wild are dwindly and under threat. This is mainly due to habitat loss, as Betta fish are usually solitary creatures which require a large amount of space.

Due to many factors such as improved healthcare and decreased conflict, the worldwide human population continues to skyrocket and South East Asia is no exception. Rice paddies and farms in Thailand are continuing to be developed, displacing much of the Betta Fish’s natural habitat.

Although Betta fish populations are declining in areas with growing human activity, their ability to survive in suitable environments is strong. A large population of Betta fish is well established in topical regions of Australia, they are considered to be a serious threat to the local ecosystem and government sponsored eradication programs have been implemented to prevent the spread of Betta fish. These fish have most likely be introduced from someone’s aquarium.


Betta fish are classified as “insectivores”, meaning they exclusively consume zooplankton, small crustaceans, mosquito larvae and other aquatic insects.

Despite their insectivore classification, Betta, especially those bred in captivity, will accept a wide variety of foods including fish pellets, brine, bloodworms, shrimp etc.

There is a common misconception that Betta fish can consume algae and other aquatic plant matter in your fish tank. This isn’t true, Betta are not omnivores and consume protein based food sources primarily.

Reproduction and life cycle

Betta fish produce sexually. Male Betta fish perform a mating dance to attract a female. If the female is interested her color darkens and vertical lines known as “breeding bars” will develop to display interest.

Breeding bars on a female Betta fish – they are less ambiguous than human females!

A very interesting trait of Betta fish is that the males have to build a house for the young to provide them with a place to live. This is highly attractive to the females.

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Male Betta fish working hard producing a bubble nest in hopes of rearing its young.

Even if there is no females present, male Betta fish will continue to create and build nests.

Bubble nests are not free floating and always attach at the surface. In nature this is usually something that breaks the surface such as a rock, dead tree trunk or aquatic plant.

A female produces eggs inside her body without the aid of males when she is ready to breed, however in order for these eggs to be released a “nuptial embrace” is required when the male hugs the female’s body, causing her to release her eggs. During each embrace, the female will release 10-40 eggs, the  pair will continue to embrace until the female has no eggs remaining.

Once the eggs are released, the male releases milt (semen) into the water to fertilize the eggs. Once the eggs are released, the male pick sup the eggs with his mouth and puts them into the bubble nest. Sometimes the female male help the male do this but usually she just eats up the eggs she has just laid.

Once the female has laid the eggs, the male will chase her away otherwise she will try to devour the eggs she has released. If the female cannot be chased away (she cannot escape) such as the case when they are kept together in a small space, the male will have no other choice but to try and kill the female to protect their offspring.

The eggs will be cared for by the male. The male betta fish ensures that the eggs remain in the egg, he will fight off any threats, put any eggs that have fallen out back inside and repair the nest from any damage. He does not need to work hard for too long to protect his babies because the incubation period is as short as 24 – 40 hours. The newly hatched betta fish larvae will remain the the next for the following 2-3 days until they fully absorb the nutrients from the yolk sac in their egg.

The baby larvae fish develop the ability to move on their own, they enter a stage where they become “fry”, they can leave the egg on their own and begin the free-swimming stage.

During the few weeks of their lives, the betta fish larvae can only use their gills for respiration. After 3-6 weeks of age, the labyrinth organ in beta fish allows them to breathe atmospheric oxygen. These figures are not concrete, the growth rate is extremely variable in betta fish.

Betta fish are known to reach sexual maturity in as little as 4 months of age, many things in tropical areas, not just fish, experience a faster growth rate due to elevated temperatures allowing faster metabolism and higher rates of nutrient utilization.

Human organized competitive fish

The aggressive nature of Betta fish has long been observed by humans, organized fights of betta fish have occurred since the 19th century in parts of South East Asia, where Betta fish were specifically bred for their aggressive tendencies.

In the wild, Betta fish usually engage in combat for a few seconds/minutes before one fish retreats without significant damage. Betta fish specifically bred for their aggressive traits can last much longer, often until a fish becomes severely injured or even dead. A duel between two fish is considered to be finished when the loser retreats.

A famous historical example demonstrating the popularity of betta fish fighting is in 1840, when the King of Thailand, a fan of Siamese fish fighting, gifted some of his prized specimens to the visiting English medical scientist Theodore Edward Cantor who wrote extensively about the experience.

First use of Betta fish as pets in aquariums

One of the earliest recoreded instances of betta fish being domesticated as pets in the western world is in 1892, when the Famous French fish breeder and importer Pierre Carbonier (center) introduced this magnificent species of fish into Paris, France.

Pierre Carbonier (center) with ichthyologists Nikolai Zolotnitsky and Andrey Meshcherskiy

In 1896, another famous European fish importer from Germany named Paul Matte imported Betta fish from Moscow to Germany.

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