# Betta Fish (*Betta splendens*)

> The betta, or Siamese fighting fish (Betta splendens), is a small, brilliantly coloured freshwater fish originally from the shallow ponds, rice paddies, and slow streams of Southeast Asia. Domesticated for centuries, it is now one of the world's most popular aquarium fish, prized for flowing fins and vivid colours. Bettas grow to about 6–8 cm and usually live 2–4 years in home aquariums.

- **Category:** Fish
- **Conservation status (IUCN):** Vulnerable
- **Range:** Shallow rice paddies, ditches, and slow streams of Thailand, Cambodia, and neighboring Southeast Asia.
- **Canonical page:** https://globalanimalguide.org/animals/betta-fish/
- **Last reviewed:** 2026-07-16

## Scientific classification

- **Kingdom:** Animalia
- **Phylum:** Chordata
- **Class:** Actinopterygii
- **Order:** Anabantiformes
- **Family:** Osphronemidae
- **Genus:** Betta

## Facts at a glance

| Attribute | Value |
| --- | --- |
| Scientific name | Betta splendens |
| Diet | Carnivore |
| Habitat | Shallow freshwater of Southeast Asia |
| Lifespan | 2–4 years |
| Length | 6–8 cm (2.4–3.1 in) |
| Top speed | Slow; short darting movements |
| Conservation status | Vulnerable (IUCN) |

## Origins and domestication

Betta splendens has been kept and bred in Thailand for well over a century, first for the sport of fish fighting and later for its ornamental beauty. Selective breeding has transformed the plain, dull-brown wild fish into hundreds of colour and fin varieties, from crimson veiltails to iridescent blue halfmoons. The name "Siamese fighting fish" comes from the males' natural aggression toward one another. Today the domesticated betta is a global aquarium staple, quite different in appearance from its wild ancestors in Southeast Asia. While the pet betta is everywhere, the wild Betta splendens is listed as Vulnerable by the IUCN, as the shallow wetlands it depends on are lost to farming and development.

## The labyrinth organ and breathing air

Bettas possess a special breathing structure called the labyrinth organ, which lets them gulp oxygen directly from the air at the water's surface. This adaptation evolved for life in warm, shallow, oxygen-poor water such as rice paddies and stagnant pools. It means a betta must have access to the surface to breathe and cannot rely on gills alone. The same trait allows the fish to survive in conditions that would suffocate many other species.

## Temperament and territory

Male bettas are famously territorial and will flare their gills and fins, or fight, when they meet another male. In an aquarium two males should never be housed together, as confrontations can be fatal. Bettas swim in short, darting bursts rather than long steady cruises, patrolling and defending their patch of water. Many become surprisingly responsive to their keepers, learning to follow a finger and rise to the surface at feeding time.

## Feeding and care

The betta is a carnivore that in the wild eats insects, larvae, and tiny aquatic invertebrates. In captivity it thrives on protein-rich pellets, frozen or live bloodworms, brine shrimp, and daphnia. Bettas need warm water, ideally around 24–27 °C, and do best in a heated, gently filtered tank rather than an unheated bowl. Good water quality and a varied diet are key to keeping the fish healthy through its 2–4 year lifespan.

## Breeding and bubble nests

Breeding bettas is a striking process centred on the bubble nest, a raft of saliva-coated air bubbles the male builds at the surface. After an elaborate courtship, the male wraps around the female to fertilise her eggs, then gathers them in his mouth and places each one in the nest. He alone guards the nest and tends the eggs and newly hatched fry, chasing the female away. This devoted paternal care is one of the most fascinating aspects of keeping the species.

## Frequently asked questions

### How long do betta fish live?

Betta fish usually live 2–4 years in a home aquarium. Good water quality, a heated tank, and a varied protein-rich diet give a betta the best chance of reaching the upper end of that range.

### Can two betta fish live together?

Two male bettas should never share a tank, as they are highly territorial and will fight, sometimes to the death. Females can sometimes be kept together in a group, but pairs are only brought together briefly for breeding.

### Do betta fish really breathe air?

Yes. Bettas have a special organ called the labyrinth that lets them gulp oxygen from the air at the surface. This is why they can survive in warm, shallow, low-oxygen water, but it also means they must be able to reach the surface to breathe.

### What do betta fish eat?

Bettas are carnivores. In the wild they eat insects and small aquatic invertebrates, and in aquariums they do best on high-protein betta pellets supplemented with frozen or live bloodworms, brine shrimp, and daphnia.

### Do betta fish need a heater?

Yes. Bettas are tropical fish that need warm, stable water of roughly 24–27 °C. An unheated bowl at room temperature is too cold and stressful, so a heated, gently filtered tank is far better for their health.

### Why is the betta called a fighting fish?

The name comes from the intense aggression male bettas show toward one another, flaring and fighting on sight. In Thailand this behaviour was once the basis of an organised betting sport, which drove the fish's early domestication and breeding.

## Sources

- [IUCN Red List — Betta splendens.](https://www.iucnredlist.org/search?query=Betta%20splendens&searchType=species)
- [Animal Diversity Web — Betta splendens. University of Michigan Museum of Zoology.](https://animaldiversity.org/accounts/Betta_splendens/)
- [Wikipedia — Betta Fish.](https://en.wikipedia.org/wiki/Siamese_fighting_fish)

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Source: Global Animal Guide (https://globalanimalguide.org/animals/betta-fish/). Licensed CC BY-NC 4.0 — free for non-commercial reuse with attribution.