Responses
I think it's because in the book, mermaids are portrayed as fish's friends, not enemies. That's why one of the guy was like "Isn't mermaids fish buddies?" lol
Fish are friends not food Σ(っ°Д °;)っ
Why was THAT such a surprise? There are plenty of fish that eat their own kind. Sharks are one such example, although they don't target each other, they will eat their own kind's corpse if it's available for consumption.