Forget what the movies told you. Piranha is not the only scary fish that exists underwater. A very close relative of the Piranha, the Pacu fish has been found in the South American waters. They are primarily known for their teeth which bear a striking resemblance to human teeth.
Generally found in shades of silver, red, brown, green, and black, these fish are often kept by people in aquariums. Pacu is also known to develop personalities as they grow older and can sometimes recognize their owners. Such fascinating behaviors make them a popular choice among some experienced aquarists. Pacu has been known to make responsive pets.
One such example was Swish, a 75-cm (30-inch) Pacu owned for over 20 years by a Chinese restaurant (Kau Kau) in the Chinatown district in Seattle, Washington. One aquarium technician said about Swish, “He’d rub his body on your arms, kind of like a dog.”
But, the most important thing that you need to know before deciding to raise Pacu is that they are an extremely large species of fish. And contrary to popular belief, some species of Pacu can reach over three feet in length no matter how confined their aquariums are.
It is not uncommon for inexperienced aquarists to purchase and raise younger specimens of Pacu only to realize that they cannot keep up with their great size and extremely demanding aquarium requirements over time. Pacus should ideally be kept in extremely large aquariums of 150 gallons or more or large outdoor ponds.
Pacu is extremely powerful and can sometimes knock glass lids off aquariums when excited. Although they are an extremely peaceful species, they are very inquisitive and have an extremely powerful bite.
There are several reports of aquarists who have been severely injured from bites by an inquisitive Pacu. This is probably why they have been releasing Pacus into lakes and other freshwater bodies. When the Pacu’s testicle-eating habit came to light in 2013, it set off a very scary reputation online for the fish. Some blamed the fish for causing the death of two swimmers in New Guinea in 2011. People were advised to keep their swimsuits tied up until such reports declined.
However, the folks at the National Geographic Studios said that the incidents of the fish biting testicles are most probably rumors. It is indeed true that their teeth are powerful and one bite can prove to be dangerous but it is highly unlikely for them to bite humans. The Pacus are originally known to be herbivore with a taste for plants, fruits, vegetables, and nuts.
“Pacu is not dangerous to humans,” says fish biologist and National Geographic Explorer Zeb Hogan, who studies the animals at the University of Nevada, Reno.
“In many places, it is illegal to release exotic species like Pacu, so aquarium owners should take the time to educate themselves about the requirements necessary to keep the fish they buy,” says Hogan.
Pacus have appeared in Arizona, Michigan, and other places, but they pose a greater threat to ecosystems than to human bathers. They are an invasive species which means, they are non-native species that can cause harm to the environment, economy or human health.
The red-bellied pacu, have also consumed the floating mats of vegetation in the Sepik River in New Guinea, which operated as fish nurseries and crocodile and bird nesting sites. Thus the entire ecosystem has become impoverished and local people cannot subsist as easily as they once did.
Thus, there is a need for increasing awareness among aquarists to not release the fish into existing water bodies but to humanely destroy the fish or contact responsible authorities.