Luna lionfish and black rabbitfish ... these are examples of "unused fish" that tend to be discarded. Why? They're unfamiliar to consumers and often difficult to process. But as the ocean heats up and familiar fish dwindle in number, these "unused fish" may become a crucial part of global food supplies. We meet a fisherman who sells such fish directly to customers and visit a restaurant that specializes in preparing unusual fish. Peter Barakan learns an easy cooking method and discovers the many benefits of unconventional seafood. Along the way, we learn about Japan's fish-eating culture.