Betta Fish (Siamese Fighting Fish)

The Siamese fighting fish (Betta splendens), more commonly known as the betta fish, is second only to the goldfish in popularity as a home aquarium pet. This small but striking species, famous for its vibrant colors and flowing fins, is equally well-known for its fierce territorial behavior.

It is an aggressive, colorful fish that is native to Southeast Asia. The betta inhabits shallow rice paddies, ponds, and slow-moving streams. Over centuries, selective breeding has produced dozens of colorful ornamental varieties that now thrive in aquariums worldwide, as the active, solitary fish makes for a lively, exciting pet.

7 Incredible Betta Fish Facts

• Although “betta” can refer to 72 other species of the Betta genus, it is used specifically for the species with the scientific name Betta splendens.
• “Siamese fighting fish” refers to the Betta splendens species in order to avoid confusion with the other species of the genus.
• Both male and female bettas are aggressive, but the females are less intense and territorial.
• The betta’s highly aggressive nature is due to artificial selection, although it is aggressive in the wild.
• The fish spawn with the males building bubble nests, after which they protect the eggs and raise the young.
• Most of the fancy bettas we see today (Half Moon, Crowntail, etc.) are selectively bred varieties, not separate wild species.
• Bettas possess a labyrinth organ, which lets them breathe air directly from the surface—an adaptation for low-oxygen waters.

Scientific Classification

The scientific name of the Siamese fighting fish is Betta splendens. It is one of over 70 species of the Betta genus. Betta comes from the word “Bettah” meaning “an ancient clan of warriors.” All bettas are of the Osphronemidae family (Gourami family). They are also classified in the Anabantiformes order.

Evolution and Origins

The Betta fish’s evolution can be traced back to a common ancestor with the gourami fish, another popular fish in the Osphronemidae family. The Betta fish’s ancestors were likely small, dull-colored fish that lived in murky waters, which encouraged the development of their distinctive labyrinth organ. This organ allows Betta fish to breathe air from the surface, making it easier for them to survive in low-oxygen environments.

The wild form of Betta splendens is smaller and duller than the popular ornamental varieties of today. They were bred for fighting for centuries in Thailand, which enhanced their aggressiveness. When bettas were introduced to the West in the 19th century, breeders focused on developing the dazzling colors and fin shapes that now define the species.

Appearance

Siamese fighting fish are small fish, usually 2–3 inches long on average (up to 3.5 inches in captivity). They can have several possible colors. While dark blue and dark red are common colors, captive bettas may also be grey, black, red, orange, yellow, gold, blue, white, violet, or even multicolored. Wild bettas are usually greenish-brown. Each species is characterized by its tails, and the betta has a typically long tail fin — long, flowing fins in ornamental types (e.g., Half Moon, Crowntail) compared to the short, rounded fins of wild forms.

Bettas display sexual dimorphism, with the males being larger, more colorful, and having longer fins; females are smaller and less ornate. All have torpedo-shaped bodies with upturned mouths that they use to eat from the water’s surface.

Varieties and Types

Though only Betta splendens is commonly kept as a pet, breeders have created dozens of spectacular varieties, including:

• Veil Tail Betta — long, flowing tail draping down.
• Half Moon Betta — tail spreads 180° like a half-circle.
• Crowntail Betta — spiky rays extend from the fins.
• Plakat Betta — resembles the wild type, with short fins.
• Koi Betta — patterned like koi fish.
• Dragon Scale Betta — metallic, scale-like appearance.

Important: These are ornamental strains, not separate species. True wild Betta species include B. mahachaiensis, B. smaragdina, and others, many of which are threatened.

Distribution and Habitat

Siamese fighting fish are native to Thailand, Cambodia, Laos, and Vietnam, particularly the Mekong Delta, and are most populous in the Chao Phraya River basin.

Their preferred habitat is shallow, slow-moving, or stagnant water, such as large puddles, drainage ditches, rice paddies, and slow-moving streams.

It is an invasive species in Australia, Brazil, Singapore, and parts of the U.S. (Florida, Texas, Hawaii), but it is not disruptive to the natural ecosystems, according to the U.S. Fish and Wildlife Service.

While in captivity, proper care involves keeping them at a warm, freshwater tropical temperature of 74-80 degrees Fahrenheit. All betta species are anabantoids, meaning they use a unique organ called a labyrinth to breathe in low-oxygen environments. In their natural habitat, bettas thrive in warm, shallow waters rich in vegetation.

Behavior and Temperament

Bettas are solitary fish and are highly territorial. Males in captivity will fight, sometimes to the death, if put in the same aquarium. They will flare their fins and gill covers as a display of dominance when threatened.

Despite this aggression, these fish are also intelligent and interactive. Many bettas can recognize their owners, follow fingers along the glass, and even learn simple tricks.

Diet

Bettas are carnivorous and consume zooplankton, brine shrimp, and other small crustaceans, and the larvae of aquatic insects, including those of mosquitoes. Bettas in captivity can be fed high-protein pellets, freeze-dried or live foods like bloodworms, brine shrimp, and daphnia.

They are surface feeders, adapted to hunting prey just below the water’s surface.

Predators and Threats

The betta’s conservation status in the wild is Vulnerable as a result of its declining population and the possibility of becoming endangered without conservation efforts. Ornamental bettas are abundant worldwide, however.

The biggest threats to wild bettas are habitat destruction, pollution, and over-collection for the aquarium trade. Its predators are larger fish, cats, newts, salamanders, and birds.

Reproduction

Bettas reproduce through spawning, starting with a mating dance in which the male and female spiral around each other. The male builds a bubble nest and proceeds to guard the eggs as well as raise the young. Gestation is 24-36 hours, and the young stay in the nest until their bodies absorb their yolk sacs. A single spawn can produce 100–500 eggs.

Lifespan

The typical lifespan of the betta is 3-5 years in captivity, with proper care. This can sometimes extend to 6–7 years. In the wild, bettas live for 2–3 years.

Betta Fish as Pets

Betta fish are popular pets thanks to their incredible colorations. Betta fish grow to be 2.5 inches long on average and require a tank that’s 5 gallons in size (avoid tiny bowls). Gentle filtration is recommended as bettas dislike strong currents. The water temperature should be between 76 and 82°F (24 to 28°C). Provide plants and hiding places to reduce stress.

One should avoid putting male bettas together, as they will fight. Peaceful companions include snails, shrimp, or certain small fish (with caution). Bettas will also enjoy live plants, floating logs, and even small “toys” to explore.

Betta fish are hardy, beautiful, and rewarding pets, but require proper care. If you provide a Betta with these conditions, it should live a long and healthy life.

Conservation

Betta splendens is listed as Vulnerable in the wild due to shrinking habitats. The major threats that bettas face, are agricultural expansion, pollution, and over-harvesting for the pet trade. There are, however, conservations efforts underway to protect the natural wetlands in Southeast Asia, regulate wild collection, and promote captive-bred bettas for aquariums.

Quick Facts (At a Glance)

• Scientific Name: Betta splendens
• Average Size: 2.5 – 3 inches
• Lifespan: 3 – 5 years in captivity
• Temperament: Aggressive, solitary
• Diet: Carnivorous (insects, larvae, crustaceans)
• Special Adaptation: Labyrinth organ for breathing air
• Conservation Status: Vulnerable (wild)