If you're looking for manga similar to Mermaid Licca-chan, you might like these titles.
Azuri, a mermaid princess, is betrothed to Prince Unagi. Their marriage is arranged to bring peace to their two kingdoms, but when Azuri falls in love with Thale, a royal guard, she doesn't know if she should save the world or follow her heart.
The series’ story centers on Marin and Urin, two mermaid sisters that long to visit terra firma. When the sisters find a ring that has fallen into the sea, they decide to venture onto land to return the ring to its high school girl owner.
Kokoro found a strange machine in her basement, as well as a variety of problems to solve!
In the year 2020 it became possible to travel to the "electric monster world" using special portable telephones. Making friends and sharing telephone numbers with the "electric monsters" became popular among humans. Our protagonist, Shigeki, is one such person. Although he originally arrived in the electric monster world on accident, he became determined to travel the world with his new electric monster companion Kuribute, and make more new friends while he was there.
The tale of a boy turned into a merman by his father and released into the sea, raised by a turtle, who befriends the daughter of Captain Nemo (who kills the turtle) and a piano playing fish who befriends a talking, underwater car in an attempt to save Nemo’s daughter from her own father because she swallowed a red pearl by becoming a member of his crew…