Aquarist Atlas
Wild Bettas · waters

The waters behind the fish

Wild bettas are creatures of specific water: a flooded rice paddy on the Chao Phraya plain, a tannin-black peat swamp in Selangor or Sumatra, a cool clear hill stream in Borneo, a seasonal Javan brook. Knowing which system a species comes from — its flow regime and, above all, its water chemistry, from neutral paddies to swamps below pH 4 — is the foundation of keeping it well. Here are the freshwater systems that shaped 78 of the 79 species in this atlas.

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Chao Phraya & central Thailand

3 species

Mainland Indochina · central Thailand

The flooded plains of the Chao Phraya, Mae Klong and Bangkok lowlands — rice paddies, irrigation ditches and still margins where the wild Siamese fighting fish (Betta splendens) and its central-plains relatives live. It includes the brackish coastal peat swamps of Samut Sakhon, home of the Mahachai betta (B. mahachaiensis).

The Mekong basin

5 species

Mainland Indochina · Mekong

The lower and middle Mekong and its tributaries across northeastern Thailand (Isan), Laos, Cambodia and southern Vietnam. A vast seasonal floodplain of paddies, swamps and oxbows where the emerald betta (B. smaragdina) and the eastern fighting bettas of the splendens group are found.

Peninsular Thailand & the northern Malay Peninsula

10 species

Sundaland · the isthmus and northern peninsula

The narrow isthmus and the northern Malay Peninsula — the Tapi and southern Thai drainages and the Thai–Malay border swamps. Where the peaceful betta (B. imbellis) and several pugnax-group and waseri-group mouthbrooders of clear and blackwater streams occur.

Malay Peninsula peat swamps

14 species

Sundaland · Peninsular Malaysia & Singapore

The acid blackwater peat-swamp forests of Peninsular Malaysia and historically Singapore — the North Selangor and Johor swamps. The classic home of the jewel-red coccina-group dwarfs (B. coccina, B. tussyae, B. livida, B. persephone) and the big-headed waseri-group mouthbrooders. Drainage and clearance have made several of these the most threatened bettas of all.

Sumatra

16 species

Sundaland · Sumatra (Indonesia)

The lowland blackwater and peat swamps of Sumatra — the Musi, Batang Hari and the eastern coastal swamps. A centre of coccina-group diversity (B. rutilans, B. uberis, B. burdigala) alongside the elongate bellica group and the adaptable B. edithae.

Borneo

29 species

Sundaland · Borneo (Indonesia, Malaysia, Brunei)

The great island of Borneo — the Kapuas, Mahakam, Barito and Rajang basins and the swamp forests of Sarawak, Sabah, Brunei and Kalimantan. The richest betta fauna anywhere: the Brunei beauty (B. macrostoma), the mouthbrooding unimaculata, akarensis and foerschi groups, and the tiny white-edged albimarginata and channoides of cool hill streams.

Java & the Sunda islands

1 species

Sundaland · Java

The streams and rice lands of Java and the lesser Sunda islands — the range of the spotfin mouthbrooders B. picta and B. taeniata. Smaller and more seasonal than the great Bornean swamps, these clear forest brooks hold the southernmost wild bettas.

Southeast Asia — other waters

1 species

Sundaland & Indochina

Wild bettas whose recorded range falls outside, or spans, the named systems above — including several recently-described peat-swamp endemics still known from a single locality. Sundaic hydrology is intricate and incompletely mapped, and betta taxonomy is still moving.

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