What is a female mermaid called?

 What is a female mermaid called?

The female oceanids, nereids and naiads are mythical water nymphs or deities, although not depicted with

fish tails. "Nereid" and "nymph" have also been applied to actual mermaid-like marine creatures purported to exist, from Pliny (cf. §Roman Lusitania and Gaul) and onwards.