One of the earliest legends of a mermaid was of a goddess who dove into a lake to become a mermaid:
Atargatis, the mother of Assyrian queen Semiramis, was a goddess who loved a mortal shepherd and in the process killed him. Ashamed, she jumped into a lake to take the form of a fish, but the waters would not conceal her divine beauty. Thereafter, she took the form of a mermaid — human above the waist, fish below —
also, from the same page:
Mermaids could also swim up rivers to freshwater lakes. One day, in a lake near his house, the Laird of Lorntie saw, as he thought, a woman drowning, and went to aid her; a servant of his pulled him back, warning that it was a mermaid
Whether this is a hoax or not, only the original poster knows for sure. We all have our suspicions when somebody claims something and then can't provide the tangible proof that we ourselves would like to see.
If you read the guidelines, you will see that we welcome all viewpoints here, and that anybody who posts them should rightfully know that they are going to be scrutinized as we try to move forward in the field. The overall integrity of Ghostvillage remains in tact. If this is truly a hoax, then it's because of places like Ghostvillage, that people can educate themselves on how to spot the difference between a hoax and something real. If we insisted on tangible proof before anybody believed anything, a lot of personal encounters would be under scrutiny, as would psychic readings.