Eel Girl

Eel Girl is a 2008 horror science fiction short film written and directed by Paul Campion, in which what appears to be a sort of humaneel hybrid woman, being studied by scientists in a Naval research facility, takes revenge on one of the scientists who are studying her.

Deep in a secret navy research facility, an armed security officer enters a secure observation room, filled with electronic monitoring equipment and shelves full of dissected fish specimens. The officer requests one of the scientists accompany her immediately. He protests, quoting navy protocols that require two people to remain in the room at all times, but the officer makes sure he knows he has no choice.The remaining scientist watches them leave the facility on a security monitor. Satisfied hes on his own, he quickly begins to activate override commands on the computer. A warning begins to sound, and the scientist steps back to stand in front of a large observation window, which looks into a dark tiled and dirty room, in the center of which stands a large bath, filled with black viscous liquid. Opposite the window is a large secure door, above which warning lights flash red, then green. The scientist becomes more agitated, breathing heavily, as he sees the door open, and a webbed hand curls around the door frame. ........

Source: Wikipedia