Stop dumping the contents of your fish tanks into lakes and ponds -- it's causing serious problems.

That's the City of Knoxville's message to people after crews removed heaps of invasive aquatic weeds and other debris from the Fountain City Lake this week. Truckloads of it.

The city said non-native aquatic plants like parrots feather grass and other watermilfoils originating on other continents were removed from the lake after rapidly spreading and covering the water's surface.

The source: home aquariums.

"Maybe they're tired of of the fish or their kids don’t want the fish anymore. They’ll come dump the fish in the lake," David Hagerman, a city stormwater engineer, said. "You think that’s the right thing to do for the fish well along with that comes the plants and other things. so even if those fish survive, those plants really shouldn’t be in here."

The city said it lowered the water recently to deal with the lake's algae problem, only to discover an assortment of colorful aquarium gravel at the bottom.

The city said it believes people had been dumping their tanks into the lake in hopes of giving their unwanted pet goldfish a new home.

“People may have the intent of giving their aquarium inhabitants a chance at life, but the reality is the fish and amphibians have almost no chance of survival, while the exotic plants are going to overtake native vegetation that serve a vital purpose in our waterways’ ecosystems,” Hagerman said. “Fountain City Lake is giving us a concentrated look at the level of damage a few little invasive plants can cause.”

Knox County brought in inmates on a work release program to spend two days yanking out weeds. In total, three truckloads of weeds had been removed.

The city also added treatment to curb the weed problem, and added 25 grass carp to the lake to feed on the plants.

Workers are optimistic their efforts combined with the cold weather will help eliminate the unwanted vegetation.

To date, the city has invested a total of $750,000 in improving Fountain City Lake in various ways.