We previously talked about the mysterious Japanese giant worms and Japanese hungry ghosts. Japan is still largely a closed country, and many monsters inhabit it, including those in the water. Legends of encounters with giant river fish of various species have circulated here for many years.

One such story, dating back to the 19th century, tells of an unnamed river in which a shoal of very strange creatures attacked fishermen and swimmers. They killed the people, then disemboweled their bodies and tore out their entrails. The person inside was found to be empty, though seemingly untouched.

Because of this strange characteristic, some researchers of mysterious creatures speculate that the purpose of these mysterious river monsters’ attacks was not to kill people, but rather to protect their territory. Survivors described the creatures as being covered in scales and having a fish-like body.

They were 1.2-1.5 meters long, with seal-like snouts and very sharp teeth. Moreover, on their heads and necks, they had something very similar to a mane of hair, almost human-like in appearance.

In Japanese myths, there is a monster called a kappa, which can attack people in the water and also likes to rip out their entrails.

These creatures were said to gather in groups on the riverbanks and be very noisy, particularly fond of playing with each other and making loud barking sounds. These creatures were mentioned in the 1823 book “The World in Miniature” by Frederick Schoeberl, and in 1996 in “Strange Magazine,” which described them as “hairy reptile-like fish.”

Some of these descriptions point to otters. They are indeed noisy and playful and love to gather in packs. And the aggressive behavior of giant Brazilian otters can frighten even a jaguar. However, even the largest and most aggressive modern otters do not attack people, much less disembowel them.

Brazilian giant otters frighten jaguar

No further modern reports of these river creatures have surfaced in Japan. Perhaps humans exterminated those otters entirely, avenging their slain relatives. Or perhaps they weren’t otters at all.

Another mysterious river creature was frequently reported during the Meiji era (1868-1912). It was most often called the Ryuu Gyo (Dragon Fish). This monstrous fish was said to be 2.4-3 meters long, with a crocodile-like head and a body covered in thick, bony scales as tough as armor.

One of the first mentions of it came from the area now occupied by Ibaraki Prefecture. Residents claimed to have caught such a fish in their nets in 1873. The gigantic fish was approximately 2.5 meters long, with a huge mouth full of sharp teeth. Its entire body was covered in sharp, bony growths.

The caught fish was shown to everyone as a curiosity until it began to rot, after which the remains were thrown back into the river.

The bony growths may identify the fish as belonging to the sturgeon family. However, the Japanese were well acquainted with sturgeon (Japan even has its own native species of sturgeon) and would hardly have confused them with another species. Moreover, sturgeon have never been found in this particular region.

Another story about the same strange, enormous fish comes from 1875, when a fisherman reported that his nets were torn to shreds by a “river animal” in Watarai Prefecture. This time, the fish was over 3 meters long. The enraged fisherman tracked it down and somehow caught it.

According to his descriptions, the fish resembled a crocodile, but had flippers instead of legs, and its entire body was covered in bony armor. The fisherman brought the captured creature back to his village, and the villagers even prepared various dishes from it. But the fish’s flesh turned out to be disgusting in taste and smelled foul.

A reptile with flippers? Looks like one of those ancient aquatic dinosaurs.

Another encounter with a dragonfish occurred in 1888. A man reported seeing a fish about 3 meters long, dark in color, with long “spines” along its back. The fish was apparently hunting a deer that had come to the watering hole and was attempting to snatch it, thrusting its enormous mouth out of the water. When a villager witnessed this, he ran in terror to call people, but by the time they arrived, the fish had disappeared from the shore.

As with the “hairy reptiles,” there have been no more modern reports of dragonfish.

Another mysterious giant Japanese fish inhabits the Nagara River in Gifu Prefecture and has been spotted in recent years. The first report came in 1989. The fish is approximately 7 meters long and has wide, wing-like fins. This fish simply flew out of the water, circled, and then splashed back in, leaving the witness gaping. He said he had never seen anything like it in this river.

In the summer of 1998, another remarkable sighting of a similar creature occurred. A group of people admiring the view from a bridge over the river were astonished to see a huge, round fish, like a large ray, skimming the surface of the water on its “wings” before disappearing from view. This strange creature was reportedly observed by at least 10 people.

Based on the fish’s rounded shape and widely spreading “wings,” it was assumed that the people had seen a large stingray. Indeed, huge freshwater stingrays, reaching a maximum length of 5 meters, inhabit the Mekong River in Southeast Asia. However, freshwater stingrays are absent from Japan itself, and the nature of the sighting remains a mystery.

Mekong freshwater stingray