A ceasg (pronounced kee-isk) is a type of mermaid in Scottish folklore who has a woman’s upper body and a salmon’s lower body. The Scottish folklorist Donald MacKenzie suggested that the ceasg may originally have been a sea goddess to whom human beings (children, especially) were sacrificed. However, MacKenzie didn’t really go any further into the story than that. He only spends a few paragraphs on this particular tale and every other source I’ve found online pretty much included the exact same info straight from the mouth of MacKenzie.
They are said to live in the sea as well as rivers and streams. It is also believed that they will grant three wishes to whoever catches them. This aspect of the lore has touches of the fairytale, The Fisherman and His Wife, which ends up being a kind of “be careful what you wish for” tale.
Stories of the ceasg tell that it is not uncommon for them to come to land and take a human lover. It is believed that they are able to shed their mermaid skin and become human while on land, which allows for these assignations. If any children should be born from these unions, the ceasg, even once she has returned to the water, will continue to watch over her her children and their descendants by protecting their boats from storms and guiding them to the best fishing areas.
The shedding of the skin and the taking a human lover calls back to folklore surrounding selkies as well as swan maidens. Having said that, in much of this lore, human men spy one of these skin-shifters, usually bathing or otherwise unclothed and vulnerable, steals their skin, and extracts promises from them. Perhaps this is where the granting of wishes aspect comes from. They aren’t so much granting wishes as they are trying to buy off their captors so that they can return to the sea.
Because honestly, none of the tales seem to be big on the idea of skin-shifter women willingly entering into sexual relationships with human men. As with so many old tales, consent is not a big aspect. There is the implicit idea that a woman must be made vulnerable and rendered unable to flee before she can be subdued into a sexual relationship.
Folklore and faiytales, y’all… they’re like a really gnarly onion. The more layers you peel off, the more horrific the stories become, and the more we want to keep peeling, maybe just because we really NEED to understand. Who knows?
Mackenzie, D. A. (2013). Scottish folk-lore and folk Life: Studies in race, culture and tradition. Obscure Press.