Red-bellied Pacus are basically vegetarian, but they are still creepy-looking fish. This is not only because their compressed bodies are very similar to those of the razor-sharp-toothed dreaded piranha, but also because their square teeth resemble those of a human being. Indigenous to the warm waters of the Amazon and Orinoco river basins, thesetropical fish are very popular with aquariums because their teeth, which are strong and used to crush nuts and seeds, are a constant source of shivery fascination to potential buyers.

This South American fish has been appearing in the waters of Michigan

According to Nick Popoff, a biologist with the Fisheries Division of the Michigan Department of Natural Resources (DNR), three of these exotic fish were captured last month in the waters of Lakes St. Clair and Port Huron in southeastern Michigan, and three more in one August week alone, which is highly unusual. Oddly twenty-six other American states have reported several pacu captures as well.

Popoff believes it is possible that most of these fish if not all, originated from the same tank where one owner kept them as pets and then, perhaps fearful of their growing size, dumped them into the lakes. These fish are chilling to behold, and can grow too large for their enclosures. They sometimes grow to a length of 35 inches (89 centimeters).

In Popoff’s own words:

“Pacus' temperature requirements are tropical, and Michigan is not a tropical state. They're not going to be able to survive our winters, so we don't consider them invasive.

We're concerned with this because this highlights the issue of pet owners releasing their pets into the wild.”

What are the implications for native wildlife and ecosystems when a foreign species invades a region?

The damage done by the introduction of a non-native species to any lake region has far reaching consequences that exceed obvious considerations. First of all, once the species gains a foothold, it is very difficult to control its spread.

Its progeny become competitors in the quest for food, dwindling the supply and thus threatening existing species. In addition, ramifications can spread into the economy of a region as well as the health and well-being of its inhabitants by decimating the industries so vital to its survival such as fishing, agriculture and tourism.

New species can be introduced, but they must complement the fish and fauna of the region

As is the case for most things in life, there’s a proper way to do them, and releasing fish into the wild is no exception to that unwritten rule.

Owners of goldfish have released their pets into Michigan lakes and they thrive year round in their new habitat. According once again to Popoff, “They're an example of an aquarium disposal over time that has created a naturally reproducing population of non-native fish."

Prevention is the key to curtailing this ever-growing problem with our national lakes and streams. Deeper still, and at the core of this particular situation, is the lack of personal responsibility.

Dumping fish that are not native to a region is both thoughtless and ignorant. Think before you dunk and ask experts what should be done. Call your state department of agriculture or even ask for advice at a local aquarium.

But don’t dump these fish into our lakes. You are killing them by doing so as well everything else that comes into their path.

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