just realized i’ve never seen any mermaid yuri

https://www.mangago.me/read-manga/sea_of_june/
https://www.mangago.me/read-manga/the_story_of_the_princess_and_the_little_mermaid/
You have now!

Here are some others other than the ones above
https://www.mangago.me/read-manga/a_monster_wants_to_eat_me/
https://www.mangago.me/read-manga/bocchi_kaibutsu_to_moumoku_shoujo/
https://www.mangago.me/read-manga/succuba_siren/
https://www.mangago.me/read-manga/between_the_sea_of_clouds/