Scleropages formosus is a large, freshwater bony fish of the family Osteoglossidae (bonytongues), native to Southeast Asia including Indonesia, Malaysia, Thailand, Vietnam, and Cambodia. Adults typically reach 60–90 cm in length and are distinguished by their laterally compressed, elongated body, large metallic scales, prominent lower jaw with two barbels, and a dorsal fin set far posteriorly near the tail. Color varieties—red, gold, green, and silver—are highly prized in the ornamental fish trade, particularly in Chinese and Southeast Asian cultures where the fish symbolizes prosperity and good fortune. The large, heavy scales display brilliant iridescence due to layered guanine crystals. S. formosus inhabits slow-moving rivers, lakes, and swamp forests, where it is a surface-oriented predator feeding on insects, small fish, frogs, and even birds. It is a mouthbrooder: males incubate large (1–2 cm) eggs and fry in their mouths for several weeks. The species is listed on CITES Appendix I, making international trade strictly regulated, as wild populations have declined drastically due to habitat destruction and overcollection. Captive-bred individuals are microchipped for trade certification. Its genome has been sequenced, revealing insights into scale coloration, teleost evolution, and the ancient osteoglossomorph lineage.