Why don’t you jump in the water with them to find out?
“I like him too and want to have his fry, but how can I, if he doesn’t want to be a spawner? Where should I deposit my eggs, hey? In his cap?” - Sh’eenaz, a mermaid in the short story A Little Sacrifice, when discussing with Geralt if she should magically change her tail into legs to be with her beloved on land, or if he should change to be with her in the water. This implys that in The Witcher universe, mermaids do not fuck.
If it’s anything like corydora, the female will suck semen into her mouth, lay eggs and then spit the collected semen on them.
reminds me of a below the waist, ‘diving with the dolphins’ tattoo a woman showed me at a bar. from the Bahamas maybe