BLUE SPRING STATE PARK, Fla. — Nature photographer Joe Cruz knows Blue Spring State Park well, but what he spotted recently while snorkeling took him by surprise.

Nature photographer spots fish that looked "like a zombie"

FWC says they're aware of the problem in other parts of St. Johns River

Officials urge any who sees sick or dead fish to reach out to FWC

“As a nature photographer, I am always on the lookout for things that catch my eye, and that obviously caught my eye," Cruz said.

He saw a school of mullet that did not look right.

"Some of their scales were missing, (and they) looked they had lesions or ulcers," Cruz said. "The first thing that popped into my mind is that they look like a zombie, because they look half-dead," Cruz said.

Knowing something was wrong, he took pictures and videos and sent them over to the Florida Fish and Wildlife Conservation Commission . Officials there said they were aware of the problem in other parts of the St. Johns River.

"FWC biologists and staff from (the Department of Environmental Protection) are investigating areas with reported fish kills and disease, specifically mullet, around the St. Johns River," a spokesperson said.

"Water samples collected from Lake George, Silver Glen Springs, and Salt Springs showed the presence of blue-green algae blooms in the area. Fish samples were collected as well. Necropsy results are pending and will take a few more weeks before results are finalized."

According to the FWC website, exposure to the blue-green algae blooms can cause nausea, vomiting, and in severe cases, acute liver failure.​