Seto No Hanayome
The series Seto No Hanayome has been licensed, it is not available in MangaFox.
From AnimeWaves:
A young boy gets saved from drowning by a mermaid but according to mermaid law, if a human sees a mermaid's true form, both are to be executed. The only solution to the problem is for him to marry her and become part of the mermaid family.