Adaro

Adaros were (formerly) malevolent merman-like sea spirits found in the mythology of the Solomon Islands.

An adaro is a unique creature that lived in the Pacific Ocean. The adaro is very dangerous, said to arise from the wicked part of a person's spirit, which is divided between the aunga (good) which dies, and the adaro (evil) which stays as a ghost (which in their introduction, when a person in the Solomon Islands dies, an aunga and adaro would both together arise, and the aunga never dies if the adaro was there). An adaro is described as a man with gills behind his ears, tail fins for feet, a horn like a shark's dorsal fin, and a swordfish or sawfish-like spear growing out of his head. They may also travel in waterspouts and along rainbows and are said to kill unwary fishermen (and/or fisherwomen) by firing flying fish at them (but in real life, they were instead said to kill enemies by firing flying fish at them, mainly vampires.

Nowadays, like all the introduced demons in the world, they are also actually peaceful and gentle since they were now introduced to real life, unlike how humans in the Solomon Islands once thought. They are omnivores, feeding mainly on the same food as humans. They are not effected by religious items, unlike in mythologies. They aren't evil and only feed on live animals in case of food shortages.