siam fighter (Betta splendens) is a small and colorful carnivorous fish. It lives in the Mekong River that runs through several countries in Southeast Asia. It is a really aggressive and territorial fish. For humans they are very popular in the aquarium trade.

Sim fighter in captivity

Sim fighter in captivity


The fish siam fighter grows about 6,5 cm in length. Life is scarce because they only live for about 5 years, although not all of them get to live that long and they only reach the age of 2 or 3 years.

Its appearance is colorful throughout its body, it is usually dull green, brown and gray, and the fins of wild specimens are short. The fins are colorful sticking out from its small body which gives it an appearance of being very sophisticated. In nature they show bright colors only when shaken. In captivity they are known for their bright colors and large, flowing fins, but these characteristics have been achieved through selective breeding. There is a sexual dimorphism between the male and the female because in the male the fins are more elongated.


The fish siam fighter it gets its name from the Thai "ikan bettah" which means the fish that bites. This fish is known to have a highly combative temperament towards other males and other smaller fish species. It is also quite aggressive against other fish of different species when they feel like a threat.


The fish siam fighter It inhabits the Mekong River that runs through all of Southeast Asia and can be found naturally in Myanmar, Laos and Cambodia, although it is believed to be native to Thailand.


The fish siam fighter It is a carnivorous fish as it feeds on other animals, therefore, its diet is based on meat. They feed mainly on insects and crustaceans. It also consumes the largest parts of food that are part of plankton.


The fish siam fighter They are preyed upon by numerous predators as they are small, unable to camouflage themselves due to their bright colors and long attractive fins. Predators are: other larger fish, cats, newts, salamanders, birds and humans who capture them to keep in aquariums.


The fish siam fighter mating begins with the courtship of the male who will widen his gills, spread his fins and twist his fins to create a dance before the female. If the female is interested in the male, she will turn her body a dark color and show vertical bars in response, called reproduction bars.

The males are in charge of creating the bubble nests on the surface of the water. The bubbles are of various sizes and thicknesses. Sometimes the male will do this for mere entertainment. Sometimes plants or rocks that pass through the surface become nesting places.

The act of spawning is known as a "nuptial embrace", as the male wraps his body around the female. Between 10 and 45 eggs are released and fertilized in each "hug." And it is repeated, until the female exhausts her eggs. The male, while hugging, releases his milk (fish sperm) and fertilization takes place externally.

During and after spawning the male has the obligation to retrieve the eggs that have not been fixed in the nest of bubbles and have sunk. Sometimes the female will help him in the process, but she usually eats the eggs. For this reason, the female is expelled from the territory by the male when he finishes releasing all the eggs. In captivity, if the female is not taken out of the aquarium, it is possible that the male ends up killing the female.

The eggs are cared for by the male. It keeps each egg in a bubble nest that must be kept afloat to prevent any from falling to the ground. He will also repair it if necessary. The incubation period is several days (between 24 - 36 hours). The hatched larvae remain in the nest for the next two to three days until their yolk sacs are completely absorbed.

Afterwards, the fry leave the nest and begin to be independent. In the first stage of their life, they are totally dependent on their gills. The organ that allows this species to breathe atmospheric oxygen is developed between three and six weeks of age. Sexual maturity is reached at 4 - 5 months.

State of conservation

The fish siam fighter It is classified as vulnerable by the IUCN. The reasons are due to the hunting they suffer to market them and the loss of their habitat.

Relationship with humans

The fish siam fighter It is highly prized by humans for its bright colors and fins. Its small size makes it the ideal fish for small aquariums. In contrast, this fish has a short life and will not become as old as other fish.

If two males are kept in the same aquarium for a long time, both males will attack each other as they are very territorial. If there is no way to escape (or way to hide) it will end in the death of one of the two. In the same way, the same thing happens with females when they live in an aquarium that is too small. It is not advisable to keep males and females together, except for the breeding season.

Sim wrestlers in bridal embrace

Sim wrestlers in bridal embrace

Popular culture

The fish siam fighter it is present in popular culture. He is the main character in the novel Rumble Fish and in its subsequent film. In both, the Motorcycle Boy character is fascinated with the creatures and calls them "Rumble Fish."

In one of the scenes from the James Bond film From Russia with Love three fish are shown fighting while the villain Ernst Stavro Blofeld compares the fish fight to the modus operandi of the criminal organization SPECTER. The fish fight to the death, and then kill the weakened victorious fish.

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