Betta mulyadii is a species of tropical freshwater fish in the family OsphronemidaeBetta mulyadii Ding, Lei, Haryono, Shi & Zhang, 2025. (n.d.-b). FishBase. Retrieved October 3, 2026, from https://fishbase.se/summary/Betta_mulyadii.html endemic to Sumatra, Indonesia. It is threatened with extinction, and is kept as an aquarium fish.
Description Betta mulyadii is a diminutive,Species Profile: Betta mulyadii. (n.d.). Aquarist Species. Retrieved October 3, 2026, from https://aquaristspecies.net/species/806/ 22.4–28.4 mm long (SL), facultatively air-breathing, tropical freshwater fish with a slim body and conspicuous red colouration. The small, rounded head is grey to rose coloured. The males exhibit a more intense colouration.Betta mulyadii. (2025, October 21). Tropischevissengids. Retrieved October 3, 2026, from https://www.tropischevissengids.nl/vissen/labyrintvissen/betta-mulyadii The narrow dorsal fin has 8–10 rays.
Taxonomy It was described by Jiali Ding, Wen Lei, Haryono Haryono, Wentian Shi, and Wanchang Zhang in 2025.Betta mulyadii Ding, Lei, Haryono, Shi & Zhang, 2025. (n.d.). ZooBank. Retrieved October 3, 2026, from https://zoobank.org/NomenclaturalActs/C327437A-2C23-4255-BF77-EE2310DCD5A8 It is part of the Betta coccina species complex.Ding, Jiali & Lei, Wen & Haryono, Haryono & Shi, Wentian & Zhang, Wanchang. (2025). Phylogenetic analysis of Betta coccina complex (Teleostei, Osphronemidae) from Peninsular Malaysia and Sumatra Island with descriptions of two new species. ZooKeys. 1238. 161-181. 10.3897/zookeys.1238.142857. The type specimen was collected by Mulyadi Tjoa Hong Tjai in an oil palm plantation in Riau, Sumatra, Indonesia in November 2023 and the exact location of the type locality is kept secret, due to conservation concerns. After its initial discovery by the Indonesian fish expert Mulyadi Tjoa Hong Tjai in 2012, it was sold as Betta sp. 'api-api' in the ornamental fish trade.Fräßdorf, D. (2026, September 30). 5 Animal Species: Just Discovered—and Already Threatened. Artensterben. Retrieved October 3, 2026, from https://www.artensterben.de/en/5-newly-discovered-animal-species-already-threatened/ Betta mulyadii is the sister group to Betta iaspis. Etymology The specific epithet mulyadii honours Mulyadi Tjoa Hong Tjai, who discovered the species.Linke, H. (2025, November 21). Forschung: Im Namen der Labyrinthfische. Zoologischer Zentral Anzeiger. Retrieved October 3, 2026, from https://www.zza-online.de/tiere-und-natur/forschung-im-namen-der-labyrinthfische/
Distribution and habitat It is endemic to Indonesia, where it occurs in a single area of less than 5 km2 in the soft, acidic, strongly humic blackwater of the peat swamp habitats on Sumatra. The water with a very low electrical conductivity and extremely low levels of dissolved minerals has a pH value of around 4.
Behaviour It is mostly peaceful, but the male fish may be aggressive.
Diet In their natural environment, Betta mulyadii feeds on small insects and other small invertebrates.
Breeding The male fish construct bubble nests under floating vegetation and guards the eggs and fry. The eggs hatch within 1–2 days. The fry can survive for a few days on the nutrients provided by the yolk sac.
Conservation Betta mulyadii is endangered due to agricultural use and the alteration of its habitat. It is only known from the type locality, a small, fragmented peat swamp in an oil palm plantation, next to an active oil extraction facility. The precise location of the only known population is being kept secret. The habitat is in poor condition, as the original forest no longer exists, and the remaining swamp is shaded by secondary vegetation. The IUCN red list status has not been evaluated,Mulyadi’s betta Betta mulyadii. (n.d.). Zootierliste. Retrieved October 3, 2026, from https://www.zootierliste.de/en/?klasse=5&ordnung=550&familie=550139&art=55014673Arifah, N., Sari, D. K., & Widayanti, G. A. (2025). From Waters to Screens: Looking at Wild Betta Betta spp.(Anabantiformes: Osphronemidae) Trading in Indonesia’s Online Marketplaces. Bio Palembanica 2(2): 142-153 but immediate in-situ and ex-situ conservation is needed for this species and it is likely to be categorised as critically endangered.
Use It is kept as an aquarium fish, since it was introduced to the pet fish trade in 2013.Elster, D. (n.d.). Betta mulyadii - Breeding report. Fischgarage. Retrieved October 3, 2026, from https://www.fischgarage.at/water/betta-mulyadii/ It should be kept in an aquarium with at volume of least 30 l in warm, soft, and acid water with temperatures of 24–29°C.Api api betta Betta mulyadii. (n.d.). TankBud the Aquarist’s Logbook. Retrieved October 3, 2026, from https://tankbud.com/species/api-api-betta Betta mulyadii requires a very densely planted aquarium with a few floating plants. In an aquarium setting, the fish feed on live and frozen foods, such as Artemia and Daphnia.
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