While it is not a freebie my Universal Mermaid tail (sold at Renderosity) has a Dawn fit included along with about 30 others.
(laroo, ichiro, Koshini, Aiko3, Alyson2, Antonia, Cookie, David3, Dawn, freak3, Girl3, Hiro3, jessi1, Kids4, Laura, LittleOne, Luke, Maddie, Michael3, Michael4, Miki4, Milbaby3, MyMichelle, RexFit, Roxie, Sadie, Steph3, tyler, v4aiko4, v4fantasia, v4sylph, v4UtopianFIT, v4young, victoria3) I got tired of never having a tail for the figure I wanted to use *lol*
So if you havent found a tail that works for you yet it might be worth a look
I'm working on textures for a bunch of various mermaid tail models inspired by some of the amazing silicone mermaid tails I keep staring at on pinterest and youtube. There are some really spectacular colours and patterns. I have a gorgeous blue and aqua peacock looking one on my desktop art right now.
LM