BURNSVILLE, Minn.—Officials in Minnesota said they’re finding more giant goldfish in waterways, prompting a plea to citizens to stop illegally dumping their unwanted fish into ponds and lakes. The goldfish, which can grow to the size of a football, compete with native species for food and increase algae in lakes. Officials in the Twin Cities suburb of Burnsville found 10 fish in Keller Lake earlier this month while doing a water quality survey. On Monday, 18 additional fish were found. Some were 18 inches (46 centimeters) long and weighed about 4 pounds (1.8 kilograms). “Please don’t release your pet goldfish into ponds and lakes!” the city said in a tweet. “They grow bigger than you think and contribute to poor water quality by mucking up the bottom sediments and uprooting plants.” Burnsville officials have worked with Carp Solutions, a startup company that develops new technologies for controlling carp, a larger …