Are there black mermaids?
Mermaids are fictional creatures from European mythology. The typical depiction of these mythical creatures includes a human female upper body and a fish-like lower body. In typical European depictions, mermaids feature straight hair and pale skin. 
However, in the context of mystical water creatures, similar concepts exist in other cultures as well, such as Ọṣun a water deity in the traditional religion of the Yoruba, who is typically illustrated as a female West African woman and, depending on the representation, may have fins instead of legs.