Salmonidae

Biwa trout

Oncorhynchus rhodurus

Trout of Japanese Waters

• Temperate
• Local endemic species
• Restricted distribution
• East Asia
• Medium
• Temperate fish

The Biwa trout, or Biwa salmon (Oncorhynchus biwaensis) is an anadromous salmonid fish of the genus Oncorhynchus, endemic to Lake Biwa in Shiga Prefecture, Japan, but also introduced to Lake Ashi and Lake Chūzenji. This species was previously identified to be same animal as Oncorhynchus (masuou) rhodurus which is first described from Lake Ashi. However, The Biwa trout was found to be a separate species from O. rhodurus and was described as a new species in 2025.