Source: independent.co.uk
Fish like the one pictured here are called "Pacu Fish" in English, a collective term for the vegetarian fish of the family Cyprinidae, native to South America, that have square, flat teeth, just like human teeth. It looks like you have dentures.
It seems to be a carp but not a carp, and the name pomfret is not a pomfret
Pacu belongs to the family Cyprinidae, a very diverse group of freshwater fish found mainly in Central and South America. Although some species of the family Saw Carp often have "pomfret" in their Chinese names, they are not in fact pomfret , and pomfret is a sea fish of the order Perch; Of course, they do not belong to the carp either, and the common carp belongs to the order Cypriniformes.
Both Pacu and Saw Carp may sound unfamiliar, but the carnivorous species of the Saw Carp family is famous, the so-called "piranha", known for its extremely sensitive blood and fierce appearance. Pacu's flat teeth and huge size may seem somewhat out of place compared to piranhas, but they are actually gentle herbivorous fish.
Common fish known as Pacu are the following:
01
短盖肥脂鲤 Piaractus brachypomus
Also known as "freshwater pomfret", it is the most recognizable of all the pacu fish, with its signature red belly. It is found in the Amazon and Orinoco river basins of South America.
The red color of the abdomen is more pronounced in childhood
图源：US Geological Survey
02
大盖巨脂鲤 Colossoma macropomum
This is one of the largest fish in the sawfat carp family, with a body length of up to 1.08 meters and a darker body color, which is highly valued in fish farming because of its large size, fast growth and strong environmental adaptability.
They are similar in appearance to short-capped fat carp, but larger and darker in color
图源：Wikipedia
03
细鳞肥脂鲤 Piaractus mesopotamicus
Also known as "pomfret". Its scales are fine and dense, distributed in the Paraguay and Paraná river basins of South America, and are smaller than the first two, with a body length of about 40 centimeters.
It is said to be delicious
图源：US Geological Survey
01
骨脂鲤 Ossubtus xinguense
It is found in the basin of the Hingu River (a tributary of the right bank of the Amazon River) in South America, and is about 17.6 cm long, but can also grow to a larger size. It has a greenish hue and is silvery-white and inhabits bottom or mid-pelagic waters, feeding on algae.
骨脂鲤的雄鱼（a）和雌鱼（b）
Image source: ResearchGate
My hometown is far away
Pacu fish are native to Central and South America and inhabit a variety of freshwater environments on the South American continent. Their most important natural habitat is the Amazon River Basin, which spans Brazil, Peru, Colombia and many other countries.
The area has a complex river system, floodplains and forested waterways that provide an ideal habitat for these fish. In particular, the local vegetation is dense, and plant seeds that fall into the water are an important food source for them.
Similarities and differences with "piranha".
01
tooth
The teeth of the Pacu fish are flattened and square, and their morphology resembles the molars of humans; The carnivorous "piranha" teeth, on the other hand, are sharp triangular in shape.
The teeth of the Pacu fish are quite straight
图源：seriouslyfish
02
figure
Pacu fish are probably one of the largest freshwater fish, and they are larger in size than carnivorous "piranhas". For example, tambaqui can reach a length of 1.08 meters and weigh up to 29 kilograms. In addition, they have a rounder body shape, while predatory "piranhas" are streamlined in size.
03
鳍
Saw carp have multiple fins, each with a specific function. The dorsal fin plays a key role in maintaining upright stability and facilitates travel in slow-moving rivers. The dorsal fin also prevents the fish from tumbling.
They also have a well-developed caudal fin, which provides the necessary propulsion for swimming, chasing food, and evading predators. The pectoral fins on both sides help the fish maintain balance.
"Piranha" VS "Fishwatch"
These subtropical fish are predominantly vegetarian and include a variety of fruits, nuts and seeds, as well as aquatic plants such as algae. Insects, small fish, or other aquatic invertebrates may occasionally be eaten, and they may shift to omnivorous when the fruit yield of the plant they like to eat decreases.
As a vegan fish, Pacu is not usually a threat to humans, but they do look a little scary with their human-like teeth and strong bite force. Although there is information that Pacu has attacked swimmers, it has not been confirmed.
The story actually comes from a somewhat nasty joke: since they feed on nuts, it is possible to gnaw on the nut-like parts of a swimmer's body: the testicles. Out of a fear engraved in the DNA, the sensational legend of the "Egg-Cut Fish" spreads (Fish: Are You Polite).
Of course, Pacu fish are also excellent edible freshwater fish, their flesh is white and their taste is mild and delicate. Due to its fast growth, high yield, easy to raise, easy to fish, and strong disease resistance, it is a popular food source in South America, and has been introduced as a food fish culture on the mainland.
来源｜Howstuffworks
Translation: Wu Ke
Edit|Not Finished