Ai to Ningyo-hime

Shio, a man with the peculiar quirk of expressing affection through preparing and serving fish, meets a mermaid. His first instinct? To fillet and eat her! But he soon learns their families share history: long ago, his ancestors were saved by mermaids, and in gratitude, vowed to wed their descendants. As it turns out, this mermaid and Shio might be connected by more than just fate... (Source: MangaDex)