Iwana

Iwana, written 岩魚 in Japanese, is a common name for several species of freshwater char in the genus Salvelinus that inhabit cold, clear rivers and streams in Japan. The term literally means “rock fish” and refers to multiple regional populations rather than a single scientific species.

Taxonomy and species concepts: Iwana belongs to the family Salmonidae, order Salmoniformes, within the genus Salvelinus. In Japan, local populations are typically treated as iwana stocks rather than a fixed species, with classifications varying among authorities. They are generally considered forms of river-dwelling char rather than distinct taxonomic units in every region.

Habitat and biology: Iwana favor highland, fast-flowing streams with rocky or gravel substrates. They are adapted to cool, well-oxygenated water and feed on aquatic invertebrates, small fish, and occasional terrestrial insects. Many populations migrate upstream to spawn in autumn or winter. Lifespans and precise life histories vary by population, but they are commonly multi-year residents of mountain streams.

Cultural significance and distribution: Iwana are valued in sport fishing and regional cuisine in Japan, where they are celebrated for both their flesh and as emblematic inhabitants of mountain rivers. The term reflects the ecological and cultural importance of riverine char in Japanese natural history. Outside Japan, the name iwana is rarely used, and related fish are described by their scientific names.