A South American fish with uncannily human-like chompers has been unexpectedly showing up on Michigan anglers' hooks.

The fish are red-bellied pacus (Piaractus brachypomus) and are piranha relatives, though their diet is mostly vegetarian. Pacus are popular with aquarium owners for their unusual square teeth that look remarkably human —rather disturbingly so, in fact. But recently, pacus have been sighted in places where they shouldn't be: Lake St. Clair and Port Huron in southeastern Michigan, where three pacus were caught during the month of July.

The pacus were almost certainly introduced into the lakes by former owners who kept them as pets, according to a statement released Aug. 9 by the Michigan Department of Natural Resources.

Pacus are native to the Amazon and Orinoco river basins and flood plains. Their flattened bodies resemble those of their sharp-toothed piranha cousins, but their own distinctive teeth are used for crushing seeds and nuts. Pacus can grow to be about 35 inches (89 centimeters) in length, and pet owners may be dismayed to find that their exotic pet can outgrow its tank, which can prompt them to release the fish in the wild, according to the DNR.

Warm temperatures are vital to the pacus' survival, so they are unlikely to become established as an invasive species in Michigan's seasonally cold waters. However, releasing pets in the wild is not only harmful to the animals and likely to result in their death, but could have severe implications for native wildlife and ecosystems, DNR officials said in the statement.

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