Bioecology, Conservation Status and Breeding Efforts of Wild Betta Fish (Teleostei: Osphronemidae) in Kalimantan, Indonesia

Kalimantan, the Indonesian part of Borneo, is a major centre of diversity for wild Betta species (family Osphronemidae), harbouring 29 species grouped into 11 species complexes. These fishes occupy specialized habitats such as blackwater streams, peat swamp forests and acidic lowland rivers. Despite their ecological significance and popularity in the ornamental fish trade, many species are threatened by rapid habitat loss, overharvesting associated with the aquarium trade and pollution. This review synthesizes current knowledge on the diversity, distribution, habitat preferences, conservation status and breeding efforts of wild native Betta species in Kalimantan. Species‐rich provinces such as West Kalimantan and Central Kalimantan support many localized endemics highly sensitive to environmental change. Peat swamp degradation and conversion to monoculture plantations are major threats to many habitat‐specialist Betta species, several of which are classified as endangered or critically endangered. Captive breeding efforts remain limited and are largely conducted by hobbyists, with few science‐based protocols in place. To ensure long‐term conservation, integrated efforts involving habitat protection, sustainable harvest management and ex situ conservation through captive breeding are essential. This review highlights the urgent need for coordinated research and conservation programs to preserve Kalimantan's unique Betta fauna.