Betta Halfmoon Male

The Halfmoon Betta is one of the most visually spectacular freshwater fish available in the aquarium hobby. A selectively bred strain of Betta splendens — the Siamese Fighting Fish — the Halfmoon morph is defined by its extraordinary caudal fin, which spreads to form a perfect half-circle (180 degrees or greater) of flowing, iridescent fabric-like fin material. Combined with the elongated dorsal and anal fins of the Halfmoon type, a fully flared male Halfmoon Betta presents one of the most dramatic displays in all of freshwater fishkeeping.

Betta splendens originates from the rice paddies, swamps, and slow-moving streams of Thailand, Cambodia, Vietnam, and surrounding regions in Southeast Asia. Wild Bettas are considerably smaller and less colourful than the domesticated forms, with relatively modest fins. Centuries of selective breeding in Southeast Asia and, more recently, worldwide, have produced an enormous diversity of tail types, body shapes, and colour patterns.

Bettas are labyrinth fish — equipped with a specialised organ that allows them to breathe atmospheric oxygen directly from the air surface. This makes them uniquely capable of surviving in low-oxygen environments but also means they must always have access to the water surface.

Male Bettas are famously aggressive toward each other — two males placed together will fight, sometimes to the death. Each male requires his own territory. However, a single male can coexist peacefully with many other species, and in a sufficiently large, well-planted community aquarium, Bettas can make spectacular centrepiece fish.

Tank Setup: A minimum 20 litres for a single male Betta — larger is always better. Heavy planting with fine-leaved plants provides both shelter and territory markers. A gentle filter (sponge filter is ideal) is essential — Bettas cannot tolerate strong water flow that buffets their fins. Floating plants provide surface cover and shelter. A lid is essential as Bettas jump.

Water Parameters: Temperature 24–30°C; pH 6.0–8.0; GH 3–15 °dH; KH 2–8 °dH. Bettas prefer warm water — below 22°C they become lethargic and disease-prone. In Belgium, a reliable heater set to 26–28°C is essential.

Feeding: Carnivore. In the wild, Bettas eat insects and their larvae. In captivity, feed high-quality Betta pellets (protein-rich), frozen or live bloodworm, brine shrimp, and Daphnia. Feed once to twice daily in small amounts — overfeeding leads to constipation and swim bladder issues. Fast one day per week.

Tank Mates (if community kept): In a 60+ litre well-planted tank, a Halfmoon male can coexist with peaceful, short-finned, drab-coloured species: corydoras, small tetras (ember, neon), rasboras, and Otocinclus. Avoid guppies (males resemble rival Bettas), Tiger Barbs (fin nippers), and any fish with flowing fins.

Behaviour: Males flare their fins when they see their reflection or another male — this is normal. Do not place males where they can see each other. The flaring display is spectacular to observe briefly but sustained stress from a permanent rival is harmful.

Health: Prone to fin rot (bacterial) in dirty water, ich under stress, and swim bladder disorders from overfeeding. Pristine water (weekly 25–30% changes) and appropriate feeding prevent most issues. Never use a tank without a heater for a Betta.