The Monster Fish of Lake Amehata （雨畑湖の怪魚） is a cryptid reported from Lake Amehata, a dammed lake in Yamanashi Prefecture, Japan.
Sometime in the early 1970s, a local resident saw a "monster fish similar to Nessie" on a foggy day in Lake Amehata. It appears that there was more than one sighting, but no further information is known.
In June 1972, a survey team from the University of Yamanashi investigated the lake, but found no trace of the cryptid.
This cryptid is unreliable because it is only known as a sighting from the early 1970s; cryptids were booming in Japan in the 1970s, so it may have been a hoax concocted to take advantage of the fad.