Colorado Parks and Wildlife officials removed 14 massive, invasive carp from a pond at an Arvada park last week, more than 30 years after the fish were introduced as part of a national study.

State officials were tipped to the presence of bighead carp at Jack B. Tomlinson Park by an angler, Colorado Parks and Wildlife said in a news release Monday.

Agency officials removed the fish after stunning them with an electric current in the water Wednesday. The 14 carp appeared to be left over from a 1992 study to see whether they could reduce nuisance algae, state officials said.

It’s unusual for bighead carp to live that long, CPW spokesperson Kara Van Hoose said in an email, but the fish didn’t have any natural predators or competition for food in the pond.

Bighead carp, which are part of the Asian carp family, usually live up to 16 years but can live longer, according to the U.S. Fish and Wildlife Service.

These carp were all at least 3 feet long and weighed more than 40 pounds, with the largest weighing in at 46 pounds.

Bighead carp are not native to Colorado and negatively impact the ecosystem by competing with other fish for plankton, their main food source, state officials said.

The size of the fish indicates they are left over from the 1992 study, which ended in 1995. The fish did not reproduce, which state senior aquatic biologist Kyle Battige described as the “best-case scenario.”

State officials will continue checking to make sure there are no remaining carp, and anyone who sees a “suspicious aquatic species” can report it by filing a report.

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