Don't pee in the river, it will attract "tench fish"

In 1829, German biologist Carl Friedrich Philipp von Martius went to the depths of the Amazon to participate in the fishing ceremony of the indigenous people. He was surprised to find that the genitals of the indigenous men were tied with layers of bands, as if they were carrying a small mummy. Martius curiously asked the indigenous people, is this a blessing ceremony? Is it to help you catch more fish?

The result was quite unexpected. This "lower body prop" is to protect the vitals from the notorious "parasitic fish" of the Amazon, the Vandellia cirrhosa (it can also prevent being bitten by piranhas). Legend has it that they will drill into the urethra and cause people to suffer unspeakable pain!

It’s better not to know the details | Pixabay

Mazius was very surprised. He tried every possible way to figure out the habits of these "dirty" fish. Soon, the opportunity came. Among the catch, the natives found a parasitic catfish on the gills of a large catfish. When Western scholars first saw this fish, which was only 2.5 cm long (Mazius encountered a sub-adult fish at that time), they could not help but marvel at it. How could such a small guy frighten the natives who had lived here for generations?

Tendril parasitic catfish | Murilo Valente-Aguiar et al. / Forensic Science Medicine and Pathology (2020)

Looking for urine?

After Martius, Western scholars were attracted by this little creature one after another, and everyone had a big question mark on their heads: Can they really get into the urethra? At least in Martius's records, he expressed doubts, because during the dissection he found that the main sensory organ of the catfish was the eye. Could it be that they have another "urine sensor" to detect mammals (including humans) peeing in the river and hit the hole in one shot?

A few years later, French biologist Castelnau came here and also discovered an incredible scene: when the native men urinated on the river surface, they actually attracted the parasitic catfish. Due to the limited experimental methods at the time, he could not determine whether the fish were attracted by the smell of urine itself or by the vibration of the river surface. He only made a record in his diary without making a conclusion.

Vandellia plazaii and Pristigaster | Biodiversity Heritage Library

Later, when the German biologist Edward Poeppig was traveling in the South American rain forest, he heard the legends of other tribes: "In fact, the catfish will not enter the body of a man. On the contrary, they prefer the body of a woman. Those tribes that claim that the catfish will enter the body of a man are just too timid!" The catfish lives in turbid water, so it seems that the possibility of "going astray" cannot be ruled out. The legend of the "blood-sucking fish" became more confusing.

A hole-in-one?

The above stories are from one or two hundred years ago. Many records are limited by the times, and many are just hearsay. So are there any modern cases of parasitic catfish entering the human body? There is a news report that happened in Brazil in 1997. A 23-year-old young man claimed that he was attacked by a parasitic catfish. He drove two hours to Manaus, Brazil to find Dr. Anoar Samad. Samad did his best to remove a 133.5 mm long and 11.5 mm thick parasitic catfish from the young man's body, and finally saved his "little brother".

According to Dr. Samad, the young man was attacked by a parasitic catfish because he urinated while swimming. If it weren't for his superb skills, his life would have been in vain. The "culprit" was preserved in a bottle of formalin by the doctor and shown to patients. This incident caused a great shock in Brazil, especially for children who swim in the river!

A parasitic catfish sucking blood from a fish's gills | Jansen Alfredo Sampaio Zuanon & Ivan Sazima / Vertebrate Natural History (2004)

But two years later, American marine biologist Stephen Spotte questioned Dr. Samad's statement. He met with Samad and personally examined the parasitic catfish sample. The parasitic catfish has barbs on its gill cover, which will open when it drills into the gills to suck blood. The barbs will fix it in the gills, so if this catfish, which is nearly as long as a tiger's mouth and as thick as a finger, is really stuck in the urethra, it is not so easy to remove it completely.

Finally, he came to a conclusion: if the fish could easily get into the male urethra and be taken out intact, the probability is no higher than that of a person being struck by lightning and bitten by a shark at the same time. The truth is still unknown.

The Little Devil

The catfish is a small translucent fish with a slightly blue color. It is generally less than 10 cm long. It is also called toothpick fish or vampire fish. It belongs to the genus Vandellia. They will wait for an opportunity to drill into the gills of other Amazon fish, especially those catfish at the bottom of the river, which is their only choice. After drilling into the host's gills, the catfish will frantically suck the blood flowing in the gills. At the same time, the sharp spines on the gill cover used for fixing will tear the gills, which may cause a lot of blood loss or serious trauma to the host. In extreme cases, it may even cause the death of the host.

A, A parasitic catfish that drinks blood. B, A parasitic catfish that hangs itself in the gills of a fish to suck blood. | Vidal Haddad Junior et al. / Journal of the Brazilian Society of Tropical Medicine (2021)

In terms of parasitic mode, the catfish is not very rare among parasitic organisms because the design of the creation of heaven and earth is too abnormal. In nature, whether it is the iron wire worm or the double disc trematode, the parasitic mode is more complicated and abnormal than the catfish. However, the panic caused by the catfish in the Amazon rainforest is much greater than that of other species. After all, some parts of the catfish are too fragile.

Some of the protein metabolites of fish are excreted through the gills, so ammonia is excreted from the gills. Therefore, people once believed that catfish can sense ammonia and find fish blood meals, and peeing in the river will attract them to "go for it". However, scientific research shows that catfish are only sensitive to vibrations, not to the smell of ammonia, so they don't have any special feelings for urine.

Stegophilus insidiosus, also a blood-sucking fish that lives in the gill cover, is only 4 cm long | CH Eigenmann / Proceedings of the Indiana Academy of Science (1917)

Throughout human history, there are countless legends about monsters, including those with three heads and six arms, and those that can fly in the clouds. As our understanding of the world deepens, more and more supernatural phenomena are being debunked and turned into equally amazing facts. If you want to see what the "vampire fish" looks like, you are welcome to visit its specimens at the Natural History Museum in London, England.

This article comes from the Species Calendar, welcome to forward