@ nightmoon, no, just be nice and hopefully you can explain things and not upset the questioner.
magic is energy, it's not an all powerful thing that can do everything. in the physical realm, it cannot change DNA physics, matter, or other things. they can do illusions, but that's about it in terms of change. the astral realm though, you can physically change, it's where 'mythical creatures' dwell. look into that, it probably holds the answers. spells and potions unfortunately won't work here to turn you into a mermaid.