Care guide · Freshwater · fish

Siamese fighting fish

Betta splendens

Photo: ivabalk · Source · CC0Resized and compressed; no cropping or colour changes.

A Siamese fighting fish immediately draws attention through colour, flowing fins and an inquisitive gaze. Behind that appearance is a territorial fish whose needs differ sharply from those of a shoaling species. Betta splendens originates in Southeast Asia, while familiar aquarium forms have been strongly shaped by selective breeding. A male is best planned as the sole fish in a heated, filtered, planted aquarium. Living alone does not mean living in a tiny, bare or unstimulating container. Gentle flow, safe resting leaves and access to warm air are important. Its labyrinth organ allows air breathing but does not make dirty water acceptable. The key choice is therefore an environment where this individual can swim, rest and feed calmly rather than a spectacular community that constantly challenges its territory.

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At a glance

Temperature: 24–28 °C
pH: 6.5–7.5
GH: 8–12 °dGH
Aquarium length: At least 45 cm
Minimum aquarium volume: At least 40 L
Adult size: Approximately 6–7 cm
Group size: 1 individuals
Swimming zone: Surface, Middle
Temperament: Territorial
Lighting preference: Subdued lighting
Cover: Plants and sheltered areas
Staple food: Fine flakes
Supplementary food: Live food, Frozen food, Finely crumbled dried natural food

About this species

The body reaches around 6–7 cm; extended ornamental fins can make the fish appear much larger. Short-finned forms often swim more readily than very long-finned fish, but remain territorial. The photograph shows an ornamental captive form, not proof of a pure wild lineage. Males often have more conspicuous fins, although not every short-finned fish is female.

The labyrinth organ permits breathing at the surface. This is an ecological adaptation, not justification for an unfiltered vase. The species belongs to Osphronemidae. Choose an alert fish that swims and feeds well, and give extreme fin forms particular attention to resting opportunities and easy access to the surface.

Natural habitat

Wild Betta splendens is known from the central Thai lowlands, among other areas within its native range. Shallow, slow or still vegetated waters change with the seasons. Rice fields and marshy habitats do not demonstrate that a fish should spend its life in a tiny muddy puddle. Such landscapes offer horizontal structure, and waters may expand or connect seasonally.

Useful aquarium features are planting, gentle flow, shade and continuous surface access. A lid helps retain warm humid air above the water while ventilation remains necessary. Do not cover the entire surface with floating plants. A reference to nature never replaces adequate space, heating and maintenance indoors.

Aquarium and layout

Our cautious lower planning limit for one male is 45 cm length and approximately 40 litres gross; prefer 60 cm and 54 litres or more. These litres describe a practical tank choice, not an exact biological threshold. Provide several resting sites just below the surface, soft plants and smooth wood without sharp openings. Diffuse the filter outlet so long fins are not constantly pushed around.

Use thermostatic heating, a thermometer and a suitable lid. Mature the filter before stocking. Keep an accessible breathing area and check that the fish can use the whole aquarium without struggling against the flow.

Water conditions

Choose 24–28 °C, pH 6.5–7.5 and approximately 8–12 °dGH for ordinary captive ornamental forms. Sources give wider limits, but stable moderate conditions are preferable to daily chemical adjustments. No unsupported KH target is added; pH stability still matters.

Ammonia and nitrite should be undetectable, and air breathing offers no exemption. Regular matched partial changes remain necessary. Unheated cold room-temperature water and prolonged overheating are unsuitable default housing conditions.

Behaviour and group size

The default is one male, not a pair or a female group presented as an easy beginner arrangement. Males can injure each other severely. Females may also be aggressive, and permanently keeping a male with a female does not ensure harmony. Some individuals tolerate carefully chosen companions; others do not.

Small fish, shrimps and conspicuous fins may trigger hunting or displays. Have separate accommodation ready before attempting a conditional combination. Prolonged mirror exposure or provoking threat displays is unnecessary. Plants, resting sites and predictable care offer more useful enrichment.

Feeding

Use a complete betta food with suitably small particles and a clear animal component. Natural feeding centres on small animal prey. Break flakes if necessary and watch the fish swallow them. One or two small daily meals are more practical than one large ration; adjust to body condition and consumption.

Suitable small live or thawed invertebrates provide variety. Dried Daphnia is supplementary, not a complete diet or a treatment for every abdominal complaint. Remove leftovers and ensure the filter current does not carry food beyond reach.

Breeding

Breeding is a separate planned project. The male builds a bubble nest and tends eggs and early larvae. Introducing a female can cause aggression and requires close supervision and safe separation. The female is usually removed after spawning, and the male once fry become free-swimming.

Initial food must be microscopic, followed later by appropriately sized nauplii. Warm humid air and gentle filtration matter during development. Do not begin without space, prepared starter food and a plan to separate and rehome the growing young.