15 Fighting Facts About Siamese Fighting Fish

Siamese fighting fish (Betta splendens), sometimes simply called Bettas, are those pretty fish you often see swimming all alone in tiny bowls at pet stores and carnivals. They’re highly aggressive and territorial but strikingly beautiful, seemingly disposable the way they're often treated and kept, but they have a long, rich history. If all you know about these fish is that they fight, here’s a crash course in all things Betta.

1. THEY COME FROM (WHAT USED TO BE) SIAM.

Like Siamese cats and the famous Siamese twins Chang and Eng Bunker, Siamese fighting fish originated in Siam, the nation that became Thailand in the mid-20th century. The fish are native to the central part of the country, but there are also populations further north and south and in nearby countries like Laos, Vietnam and Cambodia.

2. THEY'VE BEEN BRED TO FIGHT FOR CENTURIES.

According to the International Betta Congress, a global club for Betta keepers and breeders, no one is sure how long people have kept Bettas in captivity, but the tradition of breeding and fighting them goes back at least a few hundred years in Thailand/Siam. People took note of how the wild fish were highly territorial and attacked other fish that encroached on their space, and began arranging fights between the fish as entertainment.

3. THE FIRST FIGHTING FISH IN EUROPE WERE ROYAL PETS.

By the 1800s, Betta fighting was such a popular pastime in Siam that even the country’s monarchs kept the fish and watched them battle. In 1840, King Rama III gave a few fish from his collection to Theodor Cantor, a Danish zoologist and doctor. Cantor brought them home to Europe, where they were bred and introduced to aquariums around the continent.

4. THEY HAD TO BE RENAMED.

After introducing the fish to Europe, Cantor gave the species a formal scientific description and name. A few years later, though, ichthyologist Charles Tate Regan realized that Cantor’s choice of name—Macropodus pugnax—was already assigned to a related species. In 1909, Regan renamed the fighting fish Betta splendens, drawing from both the Malay language of Southeast Asia (ikan betah: “enduring fish”) and Latin (splendens: “shining”).

5. THOSE COLORS AREN'T NATURAL.

Wild Bettas are normally drab brown or olive in color, but can take on more intense colors as signals of aggression or as part of their courtship. After the fish’s introduction to the West, European and American breeders developed the range of colors seen in pet bettas today, from intense reds to pastel blues, through careful selective breeding.

6. THEY CAN BREATHE AIR ...

Because their native waters are often still or slow-moving with little dissolved oxygen, Betta fish have evolved a labyrinth organ that allows them to breathe in air from above the water’s surface.

7. ... AND LIVE OUT OF WATER.

During the dry season in their natural habitat, Bettas can make do in the beds of dried out streams and ponds by retreating to cavities with a little bit of water or even burying themselves in the muddy bed.

8. THOSE LITTLE FISH BOWLS AREN'T GOOD FOR THEM.

Retreating to these little pockets of moisture is a desperate move in bad conditions, but because of it, and the fish’s solitary nature and ability to live in low-oxygen environments, people often mistakenly believe that Bettas can be kept in tiny tanks or goldfish bowls and need little care. The fish actually need quite a bit of space, though—in the wild, an individual can claim a territory of up to a cubic yard. Smaller tanks and bowls allow waste to build up in the water, turning it toxic. That means more frequent cleaning and water changes, which stresses the fish out and can impact its health. Reputable Betta breeders say that a gallon tank is the minimum size, and 2.5 gallons and up is ideal.

9. THEIR SEX LIVES ARE COMPLICATED.

Male Bettas build “bubble nests” by gulping air from above the water’s surface and spitting out a mucus coated air bubble. They’ll do this over and over for hours until the nest takes shape. When it’s finished, the male flares his gills and spreads his fins to attract a nearby female, who responds by swimming towards the nest and darkening her color. After the two circle and nudge each other a bit (which can result in torn fins and missing scales), spawning happens in what’s called a “nuptial embrace.” The male wraps himself around the female and they release their sperm and eggs simultaneously into the water. The male then sets to retrieving the fertilized eggs with his mouth and depositing them in the nest. While he’s working, the female will often try to eat the eggs, so the male also has to ward her off and, after all the eggs are deposited, chase her away from the nest.

10. THEY'RE RAISED BY THEIR DADS.

Once the eggs are in the nest and mom is gone, the male fish guards the eggs and takes care of them, fighting off anything that gets too close. The eggs hatch after 24 to 48 hours, and the fry leave the nest and become free swimming two or three days after that. Once the little ones can get around on their own, the male Betta and his kids all go their separate ways.

11. THEY'RE NOT AS FIERCE AS THEY SEEM.

Despite popular belief, Bettas won’t always battle one another or other fish. While males won’t tolerate each other in close quarters, they can be kept alongside female Bettas for short periods for breeding, and with other aquarium fish that are larger and won’t be mistaken for rival Bettas. Females are generally less aggressive towards each other and can be kept together in small groups in tanks that provide enough personal space for all of them.

12. THEY'VE TAKEN OVER THE WORLD, BUT ARE IN TROUBLE AT HOME.

Bettas are one of the most popular species in the worldwide aquarium trade, and escapes from breeding farms and personal collections have led to introduced wild populations all around the world, notably in Australia, Brazil, Colombia, Canada, the U.S., and the Dominican Republic. Outside their native range, the fish can pose a threat to other species through competition, predation, and introduced diseases. At home in Thailand, though, Bettas themselves are in trouble due to pollution, habitat loss, and loss of genetic diversity from breeding with escaped captive-bred fish. Betta populations are in decline across their native range, and the International Union for Conservation of Nature lists the species as “vulnerable.”

13. PROZAC IS NO GOOD FOR THEM.

Anti-depressants can help some people, but pharmaceutical runoff into the environment can have grave consequences for Bettas. Scientists found that exposure to Prozac can reduce the size of the nest that Bettas build, the time they spend spawning, and the hatching rate of their eggs. In the study, over a third of the male fish exposed to the drug also cannibalized some of their eggs or larvae, suggesting that the drug led to abnormalities in the eggs that prompted their fathers to cull them, or had some effect on the males that made them desperate enough for food they snacked on the kids.

14. BLOFELD WAS FOND OF THEM.

While Bond villain Ernst Stavro Blofeld is known for his fluffy white cat, in From Russia with Love he also keeps several Bettas and uses them to explain how SPECTRE will wait until its enemies have exhausted themselves fighting each other and then strike at the battered victor.

15. ONE VARIATION COMES FROM A PRISON.

One breed of Betta known as the “marble Betta” originated in an Indiana state prison, where an inmate was raising the fish in peanut butter jars in his cell. His breeding experiments led to several fish with black and white patches, which he mailed to outside breeders who kept the lines going and developed different color combinations.