Looks interesting!
I don't see a mention of Killer Mermaid (aka Nymph) in the forums, but that may just be my incompetent search skills. Trailer is here
https://youtu.be/xhClk8DkF4I and it's up on Netflix now. Interesting movie, part slasher, part monster, with a gorgeous woman playing the mermaid. Not a lot of process, more of a pop change but she morphs from gorgeous to shark faced several times. Tail effect is well done and she is very easy to look at