15. Blowfish -
Although these adorable underwater critters may seem like they’d make awesome pets for mermaids, they are in fact believed to be the second most poisonous vertebrates in the world, and hence not the sort of fish Ariel would want to domesticate. Some of its internal organs, including the liver and sometimes its skin, would provoke certain death if eaten. More insane though, is the fact that THIS IS A DELICACY IN JAPAN! Yes, if one prepares it correctly, it can be consumed without danger, although understandably, only a selected few chefs are allowed to prepare this dish.