Koi Mermaids!
Stable Diffusion does not like to play nice with mermaids, but I did my damnedest to make this work. This was actually one of the first lora I ever made, but it was so unreliable on SD 1.5 that it just wasn't worth posting. Pony puts up with it much better, but still gets pissy sometimes.
Depending on what pose you're attempting, you may need to put "legs" in negatives, but as long as you've got "mermaid" in positives it's honestly not usually necessary. It's trained on a black/white/orange koi fish pattern, but sometimes gets fussy and ignores the black. If you want to nudge it to add the black back in without making random other stuff black, "calico pattern" in positives at about 0.8 strength works wonders. Throw "cat" in negatives if you do that, though.
Post your mermaids if you can~~ I've been working on this thing long enough 💀 Show me the fruits of my labourrrrr ROFL.