A little about this little Yokai
Iwana bōzu are enormous Iwana (char, Salvelinus leucomaenis), a kind of river fish, that have turned into Yōkai. They walk upright on two legs like humans and dress in Buddhist priest robes. They are found by mountain streams where people fish for Iwana and other river fish. They are often seen telling fishermen that are over fishing about the sins of their actions and encouraging them to only fish for what they need.