Fountain of Tooth: Fish with Molar-Like Teeth Catch On

If you’re an aquarium owner, or if you’ve visited one of the many family-friendly public aquariums within a few hours of Austin, you may be familiar with the red-bellied pacu, a fish native to the Orinoco and Amazon river basins and notable for having teeth similar to those in people.

Red-bellied pacu
Photo by frostedburn. A young red-bellied pacu in an aquarium.

Known by the scientific name Piaractus brachypomus, and by the alias “vegetarian piranha” for its diet and its relation to the notorious fanged fish, the red-bellied pacu is popular among aquarium hobbyists and is often included in public aquarium displays of South American river fish. The silvery fish with the striking crimson stomach is increasingly found in North American waters, however, as some pet owners who can’t accommodate the fish’s size and dietary needs dump them in lakes and reservoirs.

Molar Power: A Fish with Bite

In the wild, red-bellied pacu can grow to about 3 feet long and weigh upward of 40 pounds. They are distinguished from closely related fish such as piranha by two rows of flat teeth, including teeth much like human molars that are anchored in the jawbone.

Though the red-bellied pacu’s molar-like teeth are in the front of its mouth, they serve a similar function to human molars. We use our molars chew and grind down food into digestible pieces; the red-bellied pacu use their teeth to crush nuts and seeds, and extract the nutrients therein.

Although red-bellied pacu mostly feed on the seeds, nuts and fruit that fall from trees and drift to the riverbed, they also eat small fish and crustaceans. Like their relations the piranha, red-bellied pacu feed in so-called “bite events,” in which they take multiple individual bites; while not big meat eaters, they have been reported to give people a nip.

‘Fish with Human Teeth’

In pet stores, red-bellied pacu are typically sold as tiny juveniles. Unwitting aquarium owners often lack tanks large enough for their rapid growth. The red-bellied pacu quadruples in size after its first month.

In Michigan, the state’s Department of Natural Resources recently issued a statement asking pet owners not to dump non-native fish in public waters after multiple accounts of “fish with human teeth.” According to a news report, at least three red-bellied pacu were caught in two separate lakes in July alone.

Because of their size and feeding method, red-bellied pacu need significant space, space often not offered by home aquariums. The fish have been released into non-native waterways in more than 40 states, including Texas, according to the U.S. Geological Survey. Officials ask those who don’t have the resources to care for these and similar species to arrange a trade or donation with another hobbyist, environmental agency, aquarium or zoo; if the fish was purchased from a pet store, the shop may be able to take it back or recommend another local resource.

As a fan of fishing and the outdoors, Austin dentist Dr. Dan Matthews understands the importance of preserving the integrity of our natural resources. As an accomplished cosmetic dentist, Dr. Matthews recognizes the importance of your dental health to your overall health. To learn more about options for restoring a bright, healthy smile, please call Dan Matthews DDS, FAGD, at 512-452-2273 and schedule your consultation at our Bee Cave Road office.

Dan Matthews DDS
Dan Matthews Dan Matthews DDS The Park at Eanes Creek,
4407 Bee Cave Road
Building 2, Suite 221
Austin, Texas, 78746
(512) 452-2273
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