Going a little further north, into what is now France, Germany and the British Islands, we have the Celtic goddesses Aine and Brigit. Aine (pronounced An-yuh) is the goddess of love, fertility, fire, cattle and the sun. She has three forms: maiden, mermaid and hag. Brigit is associated with healing and fertility, and is the patroness of smiths. Aphrodite was married to a smith, the god Hephaestus. Check here under Europe to see how common healing is in mermaid history.
Now Christianity enters mermaid history, trying to suppress the ancient gods. The people who worshipped them did not want to give them up so the early church integrated them into itself. This resulted in a split: the official form of the ex-god and the folk version. The official, church version usually became saints. The unofficial versions became the magical beings of folklore: fairies, leprechauns, monsters, giants and mermaids.
The mermaid was especially popular in the British Islands, the old land of the Celts. I have read more mermaid stories from Ireland, Scotland, Wales and England than anyplace else. In these you will see the beautiful mermaid looking into a mirror while combing her hair, teaching the secrets of medicine to mortals, and having many amorous adventures.
The mermaid remained in popular culture as the times changed. Mermaid history travels here from folk tales to written stories to movies and TV. The innocent but still sexy blond beauty of "Splash"; the spunky mermaid in Disney's "The Little Mermaid"; the monstrous mermaids in "She Creature" and "Dagon"; and the far from innocent but very sexy mermaid played by Alyssa Milano in an episode of "Charmed". Like the ancient goddesses they came from, these modern mermaids appear in a wide variety of forms from beautiful to horrific.