Piranha, also known as piranha and piranha, is a general term for a class of ferocious fish native to South America. It is found mainly in the Amazon river basin east of the Andes to the Brazilian plain, as well as the Paraná, San Francisco, Cuiaba and Orinoco rivers. The number of species of pomfret is still controversial, but it is generally believed that there are about 30 species of pomfrets belonging to the cyprinid family and the subfamily Cyprinidae.
There are 9 genera in the subfamily Cyprinidae. The common feature of these subfamilies is that the body is flat and tall, with abdominal ribs and scales. There is a spine in front of the dorsal fin. The dorsal fin is long and the scales are small and numerous. However, the living habits of different species belonging to this subfamily are also very different. In terms of diet, herbivores, carnivores, semi-parasitic animals and other completely different lifestyles, the shape of teeth is also different, and some even have no teeth. Among them, carnivorous species tend to be known for their ferocity, especially the sargassum genus, whose teeth are extremely developed, and in order to make them sustainable, their teeth can be replaced. For this reason, they are called "wolves in the water".
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Does piranha live up to its name?
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Pomfret (piranha) inhabits main streams and large tributaries, especially in wide areas of rivers. Their jaws have strong, sharp, triangular teeth. When the upper and lower jaws are closed, they can bite through cowhide or even hardwood and sometimes break steel fishing hooks. They do not relax after biting their prey, and tear off the slices of flesh under the twisting of their bodies.
Although they sometimes survive alone, they prefer to roam in groups, with small ones or even dozens, and large as hundreds of them gathering together in large numbers. During the dry season, when the water turns small, they attack animals that pass by or fall into the water in droves. Although the pomfret has poor eyesight, its hearing is well developed. When animals fall into the water, the vibrations of the water waves can help them find the target of attack. For those animals that are several times or even dozens of times larger, the piranha pomfret adopts "encirclement and suppression tactics" to attack sequentially and quickly decomposes the prey into parts. The speed is incredible. Even crocodiles that usually do whatever they want in the water, once they encounter man-eating pomfrets, will also escape If the crocodile cannot escape, the crocodile will take a posture of facing the water with its back to the water and the abdomen facing the sky, using the hard back armor as a "shield" so that the piranha cannot attack its abdomen. Birds circling the surface of the water forage will sometimes use the piranha in the water as a light meal and dive into the water to peck, but in a short time it will become the prey of the piranha.
Folk legend has it that piranhas will "sweep" livestock or people passing through this water in the river. Of course, the truth is certainly not so serious, but pomfrets can also attack large mammals that fall into the water. It is said that when local herders drive livestock across the river, they usually first drive sick individuals into the river, use the "lead the tiger away from the mountain" scheme to attract man-eating pomfrets in the river, and then quickly drive the cattle across the river. The "abandoned" individual was quickly bitten by a group of piranha pomfrets, leaving only a pile of white bones.
It has also been reported that man-eating pomfret attacks humans: it is said that a cruise ship accidentally capsized in the river, and the drowning man was surrounded and eaten by man-eating pomfret, which looked terrible. As a result, in waters where pomfret is active, locals do not build nets to catch fish, as they not only break the nets by attacking the fish that have been caught, but also pose a threat to people. However, even if they occasionally attack humans, they can occur when water levels are low and food is scarce, and human behavior conflicts with them. So far, the fish, known as the "man-eater," has never actually killed a human.
Interestingly, the local indigenous people not only worshipped the pomfret as a deity, but also used its ferocity to keep it in the river near them to deter any foreign invasion.
Why "exterminate" piranhas?
Due to its peculiar shape, brilliant colors, and terrible names and legends, pomfret is often reared as an ornamental fish, with the N. sawfish being the most common. In fact, as early as 10 years ago, piranha pomfret "swept the country". At that time, there were many places across the country, including large breeding bases along the Yellow River in Shaanxi. At the end of 2002, the relevant state departments jointly issued a "wanted notice" to "euthanize" all pomfrets sold in the market and farmed and displayed in parks and aquariums. It is strictly forbidden to put pomfret in natural waters.
The reason for the policy of "exterminating and exterminating" is that they are very harmful. When it comes to the dangers of pomfret, the first thing that comes to mind is that it hurts people. In fact, what is more serious is that they are important invasive alien species. Once in new wild environments, due to their adaptability and lack of natural enemies, they multiply in large numbers, destroying other creatures. This will be a terrible disaster for the biodiversity of the local environment.
The pomfret population has invaded many rivers around the world from its homeland. In the United States, for example, they invaded the waters of the Potomac, Lake Ozarks and Lake Wennabego; in Asia, they invaded the waters of Lake Kaputai in Bangladesh. When pomfret was popular in China, there were reports that in a fish pond in Guangzhou, not only other fish were preyed upon, but also ducks in the pond were preying. Even the birds of the past did not dare to stay on the water to feed.
At present, more than 500 invasive alien species have been recorded in China. More than half of the 100 malignant invasive alien species published by the International Union for Conservation of Nature have invaded China.
More pomfret incidents have once again shown the world the existential reality of alien species invasion. In our country, although the sale of piranha pomfret is prohibited and it is strictly forbidden to put it in natural waters, some pet shops or individuals may buy it from abroad through channels such as smuggling. Therefore, there are two possibilities for piranhas in rivers: one is that someone buys it from the market for ornamental fish, or illegally imports it from abroad, and when it does not want to raise it, it is put into the river for "human treatment"; the other is to buy it directly and issue it as a "good deed". Whatever the purpose, the result of this "release" can destroy the life of river species and even endanger humans.