What should I do to become a mermaid

This is a world made up of 99.99% water there is only one continent in the whole world, and other lands exist in the form of islands in this ocean world, our protagonist has become a beauty, ah no... A beautiful male fish since then, the father of orr star hybrid sea anemone, the founder of submarine genetics and the most feared marine creature of dragons were born PS: Marine seed field flow ~ ~