Rainbow Fish Boeseman, an endemic Papuan fish whose body is split in two colors

The Boeseman's Rainbowfish, *Melanotaenia boesemani*, is an endemic fish found in Ayamaru Lake in Sorong, Southwest Papua. The mature male exhibits a distinct coloration: the front body and head are light bluish-grey to almost black, while the rear half of the body and fins are bright orange-red. The female displays a broad dark longitudinal stripe down the middle, with rows of narrow yellow or reddish-orange stripes. This unique "half-and-half" pattern is most notable in the male. The fish habitat, Ayamaru Lake, is culturally significant for the indigenous Maybrat people, who rely on it for livelihood and cultural identity. The species faces threats from overexploitation for the ornamental fish trade and the introduction of alien predators like goldfish and gastor/gabus, which prey on eggs and fry. The lake's environment is a karst lake with a water structure divided into Yahu, Yate, and Ikri areas. Conservation efforts are influenced by local practices such as *sasi*, which allows for ecosystem recovery periods. Commercial breeding has taken place in Indonesia, Europe, and the United States to supply the global aquarium market, reducing the need for wild collection.

*Melanotaenia boesemani* is found in Ayamaru Lake, Maybrat Regency, West Papua, in Southwest Papua. The male fish has a light bluish-grey to almost black front body/head and bright orange-red rear body/fins. The female has a broad dark longitudinal stripe and rows of yellow or reddish-orange longitudinal stripes. The maximum body size is 12 cm, usually less than 10 cm. Live specimens were collected in November 1982 by Gerald Allen and Heiko Bleher. The fish was first described in 1980 by Gerald Allen based on specimens collected in March 1955. Ayamaru Lake has an average depth of 30 meters and a surface area of about 980 hectares. The local name for the fish is *sekiak*. Overexploitation, introduction of alien species (goldfish, gastor/gabus), and deforestation around the catchment area are identified as main threats. Commercial breeding efforts have occurred in Indonesia since 1983–1986, alongside efforts in Europe and the United States.

The narrative frames the existence of an endemic species against a backdrop of intense external pressure—commercial exploitation and ecological disruption—while simultaneously highlighting intrinsic cultural value rooted in traditional stewardship. The transition from a naturally occurring, culturally sacred resource to a commodity for global aesthetic demand illustrates a complex dynamic of value shifting. The pattern of threats—overexploitation by external markets juxtaposed with internal environmental degradation (deforestation, sedimentation)—suggests that conservation success is not solely dependent on mitigating biological threats but on upholding and enforcing socio-cultural governance systems like *sasi*. The shift in focus from direct capture during illegal fishing to the current reliance on captive breeding suggests a potential evasion of immediate physical loss, raising questions about where true ecological resilience resides. Furthermore, the documentation shows how external interests (international aquarium trade) can drive the narrative that positions indigenous practices as necessary for survival, potentially overlooking the agency and knowledge embedded within those local governance structures. What mechanisms exist to ensure that traditional conservation frameworks are prioritized over externally driven economic valuations when addressing threats like habitat loss?