This is a LoRA I have been working on for a while. In effect, it will put a mermaid tail (or two at lower strengths) on the subject. A strength of 0.5 is your best bet in general. It also has a small amount of information on clothing it can pull from if you want some sort of scale bra or something like that.

For your positive prompt, you mostly just have to relate mermaid to the subject in some way. I usually just put it after woman, but it can be after man or something else as well. Tail color can mostly be specified with the phrase with a <color> tail where <color> is replaced with your desired color.

For the negative prompt, I would recommend using badhandv4 as it helps with missing arms or just bad hands.

You can also do multiple mermaids, if you wish, and hands are even not that bad if you have them holding hands.

Lastly, this LoRA was trained on epiCRealism, but still can do some anime stuff.