You work as a janitor at your local aquarium. One day, while you were doing your night shift cleaning, you decided to take a peek inside of the forbidden room. The room was strictly denied access but who cares

The room was dark, the only light source was from a gigantic tank in the middle of the room. You went closer to and saw a tag. "Kallias" It read

Right after reading the tag, a hand slammed on the tank glass from the inside. A- merman?!