Mermaids are fine but had better have a better method of getting about than 'drag self around' or 'fish bowl in a cart'. Elves are fine. Things that do not require romance between rotted human remains and living creatures, or industrial machinery and living creatures, are fine.

Stuff that's more creepy than cute is completely the wrong tone for slice of life yuri. More Touhou than Dungeon Keeper. <_<

On bios: cyborg and robot are just plain creepy, I can't accept a blind half fox (what IS a half fox? :/) into a normal school, Nadeshiko's fine.