Is there a mod to stop townies becoming mermaids?

[Fox]

This is really annoying and I am sick of having to remove their mermaid status with MC.

[Fox]

Anyone?

[UmYTho]

There might be something in nraas, i think you can prevent certain occults from spawning, but that's as close as you'll get.

[puzzlezaddict]

NRaas StoryProgression both blocks any sim from receiving an occult state for no reason and allows you to set the default percentage allowed for a given type of occult. The first part is just how SP works, no need to change any settings, and it may be enough for your purposes: no townies would ever become mermaids unless they were born to a mermaid parent or immigrated with the occult state already present.

I don't know of a standalone mod to prevent mermaid generation, but you could ask at NRaas or MTS. If there's a mod out there to do it, someone on one of those sites will know.