Kocchi Muite yo! Shiikuin-san!

Edogawa Aquarium—This is an aquarium that keeps an extremely rare mermaid. Nina, the star mermaid of the aquarium, is head over heels in love with her keeper (and adoptive father), Tobio Tobimatsu! With the seals that live with them watching over them, what will become of the love between the mermaid and the human? A bizarre aquarium comedy by Osamu Edogawa begins!!

(Source: Comic Ambre, translated)