Fish With Human-Like Teeth Found In Lake Michigan Highlights Dangers Of Pet-Dumping


Katy Evans

Katy is Managing Editor at IFLScience where she oversees editorial content from News articles to Features, and even occasionally writes some.

Managing Editor


Open wide. Michigan Department of Natural Resources

Anglers at Lake Michigan have hooked a surprising guest this summer, a piranha-like fish native to South America with a rather creepy defining feature: human-like teeth.

Over the past month, at least three of these red-bellied pacus, a relative of the piranha usually found in the warm waters of the Orinoco and Amazon rivers, have popped up across Michigan. According to the Michigan Department of Natural Resources (DNR), they have probably been illegally dumped in the lakes by pet-owners who no longer wanted to keep them in aquariums.  


Imported from South America as part of the USA’s billion-dollar ornamental fish industry, pacus are popular with aquarium owners because of their unusual and uncanny human-looking teeth, which are actually used to chomp on nuts and seeds, giving them the nickname “vegetarian piranhas”.

The pacu has also gained an unlikely reputation for being a “testicle-eating fish” after a professor at the Copenhagen Museum of Natural History warned local men to beware when bathing nude in case the fish mistook their crown jewels for their favorite tree nuts. After receiving a spate of reports on the fish attacking male genitals, the professor had to clarify it had been a joke.  

Unfortunately (or fortunately), the pacus often give their owners a different kind of shock – their size. They can grow up to 89 centimeters (3 feet) in length, often outgrowing their tanks, leading to illegal dumping in a convenient body of water.

It may have been a nasty surprise for the angler who accidentally hooked this strange-looking fish, but we can’t imagine the pacu, going from swimming in a warm tank to finding itself in the cold waters of Lake Michigan, where summer water temperatures average 15.5°C (60°F), enjoyed it either.


According to the DNR, the pacus are not considered an invasive species to the lakes, as they are native tropical warm water fish so are unlikely to survive the harsh winters of Michigan. However, this increase in discovering non-native species is shining a spotlight on the problem of people releasing pets into the wild.

"Pacus' temperature requirements are tropical, and Michigan is not a tropical state," Nick Popoff of the Fisheries Division of the DNR told Live Science. "They're not going to be able to survive our winters, so we don't consider them invasive. We're concerned with this because it highlights the issue of pet owners releasing their pets into the wild."

It goes without saying, dumping unwanted pets is not a good idea.  


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