If you see one of these do not approach it or it will attack you, I thought this was a non violent creature so i approached it. My frog was on neutral and the manta hit me so the frog attacked and it died since the manta brought more mantas. Beware of these horrible creatures.
If you are planning on doing anything involving water prepare to despise these flat horrors. They can out swim you. They can swarm you. They can act friendly and once you turn your back eat your tame. Beware.