Betta Trading
Siamese Fighting Fish Betta splendens


There are several species in the genus "Betta", but the best known and most spectacular is the "Siamese Fighting Fish". Although this fish is almost universally called "Betta splendens", they are hybrids and their ancestors may include Betta smaragdina, Betta imbellis, Betta sp.“Mahachai” and possibly Betta stiktos as well as Betta splendens, this is explained more fully under the title ‘fighting’ below.

This fish comes from the Mekong basin in Thailand, Cambodia, Laos and Vietnam. The old name of Thailand was Siam and this is where its most common name comes from.


Fighting fish are a tropical fish; 26 degrees C (79 degrees F) is a suitable temperature. They can take at least 8 degrees C higher than this, but will not be comfortable any lower than about 18̊ C (64 degrees F). In colder water, they become inactive and more susceptible to disease. In a temperate climate, they need heating in the winter; in a cold climate, they need heating all year. The usual way of heating the tank is with an aquarium heater.   A 50w heater is suitable for a 20-litre aquarium in most circumstances. A room that is only heated by the sun will get cold when the sun is not shining.

Some very small tanks are sold for fighting fish, and many are simply too small under any circumstances.   Some of the larger ones are suitable without a heater in tropical or subtropical areas.   If a tank is too small to put an aquarium heater in, it is too small for a Fighting Fish.

In general, the smallest aquarium I recommend for a Fighting Fish is 20 litres (5 US gallons).

Despite my opinion, many people keep Fighting Fish in much smaller tanks, and some of these people are highly experienced Betta keepers who have considerable success in both keeping and breeding these fish. The most extreme I’ve seen was in the fish room of an importer. He kept his fighters in little disposable plastic cups with only about an inch (2.5 cm) of water in them. The fish did not even have enough room to straighten up.


When I was younger the Fighting fish was classified as an anabantid, but taxonomists have revised their classification and it is currently an osphronemid, not an anabantid.  

They and their relatives can breathe air as well as water.   This means that they can live in water lower in Oxygen than most fish.   In the wild they sometimes live and even breed in very small bodies of water including the water-filled hoof prints of a water buffalo.   This does not mean that these are good conditions for the fish, simply that they are capable of surviving in them, at least for a while.

They are much more often also found in rice fields, and other large bodies of water.   They need to be able to get to the surface or they can drown.   Like other fish they are affected by water quality.   A small tank is harder to keep clean than a larger one, and usually you cannot put a filter in.



Rainwater is often used.   Some people use it successfully, but not all rainwater is safe for fish.   Rain, as it falls from the sky in some places may be good water.   When it comes into contact with the roof and gutters and then stays in the rainwater tank with any leaves etc which have washed in, it picks up contaminants.   Some of these are harmless, but others can kill fish.  

If rainwater is the only type of water available then you will need to use it.   Apart from the obvious things like keeping your gutters clear and avoiding spraying near the house or if the wind is towards the house you can add a rainwater conditioner. This will add the salts that rainwater does not have.   It will also neutralise some (but not all) of the possible contaminants.

Mains Water

Not everyone in the world who keeps pet fish has mains water, but it is the most common type of water used.   In many areas Chlorine is added to the water.   This is poisonous to fish.   It can be got rid of by adding the recommended rate of a water conditioner such as Wardley's "Tristart" or Aquarium Pharmaceuticals "Super Strength Tapwater Conditioner", or any of the many other reputable brands of conditioner. Another way is to leave it in a bucket or other open container with a large surface area for 24 hours.

In some areas Chloramine is added to the water, but in other places it is illegal to use this disinfectant for mains water.   Chloramine is a combination of Chlorine and Ammonia.   It is more poisonous to fish than either Chlorine or Ammonia separately and is much more persistent than Chlorine.   In some places, it is present in high concentrations.

Either of the two conditioners mentioned above will get rid of the Chlorine part of the Chloramine.   But they will need to be used at more than the recommended rate.   Other brands of conditioner will also work and also need to be used at a very high rate, but some of them may have other things added which can cause trouble if the rate is increased.

Where I live, in Littlehampton in South Australia, the level of Chloramine is particularly high at some seasons and on some days of the week, and we need to use the standard water conditioner at five times the recommended rate. Leaving the water in an open bucket is not a practical way of getting rid of Chloramine.   It would take several weeks.   The quite low level of Fluoride added to most tap water is believed by many people to be safe for fish.

There are some water conditioners which remove ammonia as well as Chlorine.   This also needs to be used at 5 times the recommended rate in the Adelaide Hills.

Filtered Tap Water

Some domestic water filters including Pura Tap will remove most of the Chlorine and Chloramine. The filter cartridge needs to be in good condition. If you have a filter it is a good idea to use this water for your fish.   However, because the filter may not remove all the Chlorine or Chloramine from the water, it is still a good idea to use a conditioner to be on the safe side.

Spring Water

Many types of spring water are suitable for Fighting Fish without any conditioner or modification.   If you decide to use spring water it is a good idea to test the Ph of the water.   If it is too far from neutral, you will need to adjust it.

Ph is a measure of acidity or alkalinity.   A pH of 7 is neutral.   Below 7 is acid and above 7 is alkaline.   The ideal Ph for fighters is about 7.1, but they can take moderate variations from this.   The pH of water can change, so it is a good idea to check it regularly.

Water Changes

Whatever type of water is used, in most home situations frequent, often daily, water changes are needed. The water used for the change should be the same type as used before and be at the same temperature as the water removed. This is particularly important if the fish are being kept in a small tank.

Foods and Feeding

I consider Fighting Fish to be omnivores with a strong preference for animal food. They require more animal food than most fish and many experts class them as carnivores. They prefer animal foods and in the wild will eat a wide range of animals like insect larvae, small Crustaceans and tiny worms.

In an aquarium, they will eat all normal types of aquarium foods, but do better on a food designed for them.   It is a good idea to supplement the dried food with live food like mosquito larvae (wrigglers), Daphnia, live blood worms or live black worms. If live food is not available, dried or frozen versions of these small animals can be used. I often use frozen blood worms or dried black worms. As with almost any animal a variety of food is welcomed by Fighting Fish.

If you are just keeping them rather than conditioning your fish for breeding, bettas should be fed once or twice a day. All the food should be eaten in less than two minutes. If any food is left after two or three minutes it should be removed. Do not overfeed!


One Fighting Fish can be kept by itself and this is the way most of them are kept. It is not the usual way that they live in the wild.

  Fighting fish are usually not an aggressive fish, except to each other, and can be kept in an aquarium with other peaceful fish of a similar size or smaller. Like nearly all fish, Fighting Fish will eat another fish if the fish is small enough to fit in its mouth.

Generally a fighting fish can be kept with fish as small as Neon Tetras without trouble, but the occasional Fighting Fish may learn to catch Neons.   In a confined space Fighting Fish should be by themselves. I know of at least two cases of a fighting fish which has been put in a bag with Neons and has learned to eat them.   Having learned, the fish is likely to continue to eat Neons in an aquarium.   Fish have good memories for the things that matter to them like food and danger.

Other suitable companion fish for fighters include White Cloud Mountain Minnows, Cardinal Minnows, Cardinal Tetras, Pristella Tetras, Bronze Catfish and many similar peaceful fish that do not grow too big. Some of the fish just listed prefer lower temperatures than Fighting Fish, but all can be kept at 24 degrees C (75 degrees F)

I keep Fighting Fish with Guppies and have no trouble, but many other people do have trouble keeping male Fighting Fish and male Guppies together and Guppies are not a recommended companion for a male Fighting Fish. The fighter may see the long fins of a Guppy and interpret it as being another male Fighter and attack it, or a Guppy might try to see if the long fins of the Fighter are edible and the Fighter retaliate.

One aquarist I know had a tank which had, among other fish, two male Sailfin Mollies, but no female Mollies or Guppies and one male Fighting Fish. With the lack of any suitable fish to mate with the Mollies both spent so much time trying to mate with the poor fighter that they eventually harried it to death.

A boy I met in our shop, against the advice of his parents, put a Fighting Fish with a small Murray Cod. The Murray Cod was a bit bigger than the fighter, but the boy thought the fighter was a tough fish that would stand up for itself. Unfortunately, the Murray Cod simply swallowed the fighter whole.

Goldfish are not a suitable companion for Fighting Fish.

Fighting fish are slow and have long fins. They are very vulnerable to fish that nip fins.

Some of the fish that can be fin nippers and which I would not recommend as companions for fighting fish are Tiger Barbs, Red Eye Tetras, Serpae Tetras, some Galaxies and Rosy Barbs.


Transporting Fighting Fish

Normally fighters are transported in a plastic bag.   It is important that there be some air (or Oxygen) above the water in the bag.   The bag should not be allowed to get very cold or very hot in transport.   It is better that if you are transporting a male fighter that no other fish is in with it.

Life Span

Siamese Fighting Fish are often not very long lived.   Their normal life span is about two years, but there are reports of individual Fighting Fish living up to 10 years.   The male fighters normally on sale in shops are typically about nine months old, and the females are usually about five or six months old.


The males are usually much more spectacular than the females, having longer fins and more intense colour. However, the Plakat Fighting Fish have short fins in both sexes and a good female of any variety may have colours which rival the intensity of the males.

The anal fin of the females is usually rounded, but most males have pointed anal fins. The ventral fins which are underneath the fish’s head, are usually longer in the male than the female.

Males grow bigger than females and their body tends to be less rounded. Once the female is laden with eggs the shape difference is generally obvious.

The ovipositor of an egg laying fish is where the eggs come out, and only females have them. The ovipositor looks like a small white spot behind the gills. This can be confused with a protruding vent.

Only males normally build a bubble nest, but the occasional female can also do this. In some cases, you need to take into account most of the sex differences to be reasonable sure which gender you fish is. Even experts can make mistakes.

Breeding Fighting Fish  

The Siamese fighter is considered a medium difficulty fish to breed.   Before the fish can breed they need to be in good condition; both the male and the female need to be well fed on rich animal food for some time beforehand.   The fighting fish is a nest breeder, and the male builds a nest of bubbles on the surface of the water.

An increase in temperature will sometimes induce the male to build his nest.

After the male has built his nest, you can attempt to put a female in with him.   Watch them!   It is not unusual for one of them to attack and try to kill the other.   It is not always the male that tries to kill the female.

He tries to entice a female to go under the nest with him.   They wrap their bodies round each other, and the female releases her eggs while the male releases his sperm to fertilise them.

After that the female sinks down in a sort of stupor while the male quickly picks up the eggs in his mouth and put them in the nest.   If he has not finished before the female recovers, she starts eating the eggs.   This process will be repeated until the female has no eggs left.   The male then chases her away, and she should be removed.

If another female is available, in some cases, a male will then induce her to go under the nest as well and he will raise a bunch of fry from the eggs of both females, but you are increasing the danger of problems by having two or more females in while breeding.

The male guards the nest while the eggs hatch.   He also guards the newly hatched babies until they are free swimming.   After that he will eat them unless he is separated from them. A well-conditioned female will lay about 600 eggs.

Raising Young Fighters

If you succeed in getting as far as having free swimming baby fighters, now you have the more difficult part.   The babies are so small that you need reasonably good eyesight even to see them.

They will need tiny food.   In the wild they would be eating things like protozoans.   These are single celled organisms usually too small to see without magnification, but much bigger than bacteria.   In the aquarium hobby these are usually called ‘infusoria’.   Some of these will be present in nearly all aquariums, but there will probably not be enough for the babies.   There are also fry foods made by many companies.   Fighting fish will need the finest ones at first, such as Sera ‘Micron’.

If you succeed in getting them growing, they will soon be big enough to eat larger fry food such as Sera ‘Micropan’ or HBH ‘Fry Bites’.   At all stages, fighting fish benefit enormously   from some live food of suitable size.

At around six weeks old the baby’s accessory breathing organ; the ‘labyrinth’ starts working.   At this stage, it will be necessary to have a small stream of air from an air stone or an air operated sponge filter to break up any surface film because the babies might not be strong enough to penetrate it to get air. The air above the water needs to be about the same temperature as the water with a very high humidity.

The males and females are normally separated as soon as they can be distinguished, with the males going into containers by themselves. An expert breeder will be able to distinguish the sexes of the fry at eight weeks old.


In the wild when two males meet they are likely to display to each other and may sometimes fight. In nearly all cases these fights end in one fish retreating, leaving the victor possessing the territory.

In Thailand, these somewhat aggressive fish were selected for much greater aggression so fish fights could be set up and money was bet on the outcome of these fights. It was at this time in the fish’s history that large numbers of crosses between the different species of the Betta splendens clade of the Betta genus were done so it is now difficult to sort out the exact ancestry of the modern Fighting Fish. The ones normally available today are descendants of these ultra-aggressive fish and some of the aggression that was bred into them still remains.

If you put two males together in a small aquarium they will usually fight after going through a display.   The display seems to be part of the fish’s method of recognising the sex of the other fish.   In a limited space like a small aquarium a fight would usually end with one fish dead.   In Thailand fish fights are staged with betting on the outcome.   This is a traditional ‘sport’ which is now illegal in Thailand, although this does not mean that it never occurs in that country. Based on some forums on the internet organised fish fights are quite common in some places in the United States.

The spectacularly beautiful long finned fish commonly available are only moderately aggressive towards each other. Once a man who was moving house sold me two male Bettas which he transported in the same plastic bag. He told me that they had been together in his aquarium and got on well without any fights. I took him at his word and released them together into one of our tanks. There was no trouble between them and eventually I sold them together and they continued to live together amicably in the customer’s tank.

Another customer told me how he and three friends bought four male fighting fish and released them into a four-foot (120cm) tank, intending to have a “Fighting Fish war”. The four fish retired to the four corners of the tank and totally ignored each other. You cannot rely on this sort of thing happening, but Fighting Fish are individuals with their own personality and do not always follow what the books say they are going to do.

Females can be put together with each other and one male in a reasonable sized aquarium.   Usually there is no serious trouble between them, but a tank with hiding places is a good idea.


As mentioned above the modern Fighting Fish is a complex hybrid and is no longer pure Betta Splendens, Regan 1910.

Common names for this fish in English include: “Siamese fightingfish”, "Japanese Fighting Fish", "Samarai Fighting Fish", “Thai Fighting Fish”, "Chinese Fighting Fish", "Continental Fighting Fish" and "Mexican Fighting Fish."   The "Cambodian Fighting Fish" is a colour variety of this fish.

In other languages it is “Le Combattant” in Canadian French, "El luchador de Siam" in Spanish “Siiami tapluskala” in Estonian, “Taistelukala” in Finnish, “Siamesischer Kampffisch” in German, “Trey kroem phloek” in Khmer, “Belaga” or “Sepilai” in Malay, “ 五彩搏魚 ”, “ 五彩搏 ” or “ 罗斗鱼 ” in Mandarin Chinese, “Bojownik syjamski” in Polish, “Combatente” or “Peixe de briga” in Brazilian Portuguese, “рыбка бойцовая”, “петушок сиамский” or “Petushok” in Russian, “Kampfisk” in Swedish and “Cá lia thia” in Vietnamese.


The International Union for the Conservation of Nature (IUCN) Red list classes Betta splendens as being ‘vulnerable’, with a declining population. The main reason for this, like so with many other fish and wild animals is habitat degradation caused by human activity. A secondary reason given by the IUCN is ‘Genetic erosion from escaped farmed stock into wild habitats’.

Sources and Picture Credits

The sequence of pictures by Zoofan are used under a creative commons license. By ZooFari (Own work) [CC BY 3.0 (], via Wikimedia Commons.

The picture of the fry below the nest is by Antonio Rojo (Own work) [CC BY-SA 3.0 (], via Wikimedia Commons.

The spawning sequence below this article is by Marrabbio2 (], from Wikimedia Commons.

C) Copyright is claimed for the text by Steve Challis, November  2017; this latest revision is an expansion of a fact sheet written by Steve Challis in 1990.  

Steve Challis

Crown Tail Male Betta

Here are a few of the many relatives of the Betta

Paradise Fish

Dwarf Gourami

Blue Gourami

Honey Dwarf Gourami

Pearl Gourami

Another Red Male Crown Tail Betta

Male White Double Tail Betta

Female Betta

Below are 4 pictures of few of the many Bettas at Sweet Knowle Aquatics of Stratford on Avon.

Magnificent male Black Smoke Crown Tail

Female Bettas

Crown Tail female Bettas

Male Betta


At one time, Bettas were being sold together with a plant growing in the top. The story told by some shop keepers who were either unscrupulous or did not know any better was that the fish would eat the plant roots and the vase was a self-contained ecosystem. Bettas need a diet based on animal food and if the only food was plant roots they would slowly but surely starve to death, even assuming the plant used was not a poisonous one.

Associated with the roots of a plant growing in water there will be a film of micro-organisms which might be edible by Fighting Fish, but Bettas are not well adapted to eat these and the limited nutrients from the micro-organisms would only delay the inevitable death of the fish.

Hungarian Stamp

Bettas have been used on perhaps more stamps than any other fish. A small selection of Betta postage stamps are pictured at the end of this article.

Opaque White Betta female

Crown Tail Male Betta

Bubble Nest

Male Betta under his bubble nest

Betta fry below the nest with their father watching over them. Picture by Antonio Rojo.

The 3 pictures below are by Zoofan.

Spawning embrace under a bubble nest

11 day old Betta fry in a bubble nest

15 day old Betta Fry

Bettas have been used on possibly more postage stamps than any other fish.
Vietnam is one of the countries this fish comes from so it's fitting that there are several Betta Stamps from Vietnam.

Many other countries have also featured this splendid fish on postage stamps.