Since mermaids are made-up creatures their eyes are whatever color the artist or writer wants them to be in a depiction.
Pirates & Mermaids - The Blue Sky Project
mermaids are not killers because they are just fantisised characteres. If you believe in mermaids you might just want to keep your eyes open at night.
Mermaids do not exist in real life, but there are plenty of creatures that can see well under water. Their eyes are adapted for an underwater environment.
green eyes
His eyes are blue.
If you mean a song, than that is Mika - Blue Eyes :)
Most do not have blue eyes and the ones with blue eyes are usually blind.
Blue
Blue
Eyes as blue as saphires
His eyes were blue
75% green, 25% blue eyes. Blue is recessive.