Thirteen fish have gone missing from Austin's Zilker Botanical Garden.

Workers who oversee the Koi pond noticed a number of the fish vanished a couple of weeks ago.

Horticultural supervisor Melvin Hinson said workers are "very disheartened to see their friends gone.''

Staffers located discarded fishing nets and a bag of goldfish possibly used to lure the koi.

Hinson said he doesn't think the fish heist was a one-man job. Each one is about three feet long and pretty hefty.

"If these fish are 8 pounds to 20 pounds, you can't handle more than one or two at a time," Hinson said. "You need other pairs of hands to carry boxes of water for you to get them out."

If the Koi weren't handled carefully, they could be injured or contract fungal diseases, Hinson added.

According to the Austin Parks and Recreation Department the fish are worth up to $200 each.

The missing Koi are the garden's main breeding females.

Since the theft security cameras have been installed.

The Associated Press contributed to this report.