Something eerie is swimming in one of America’s most famous lakes. At the bottom of Lake Superior, fishermen and researchers continue to catch lake trout that appear as if they are zombies pale, skinny, and floating like they are dead. There is even a nickname for these fish: “zombies.” This is no Hollywood story; it is a true case of ecology gone awry.
The fish are siscowet lake trout, a fat type of lake trout, which are accustomed to being heavyweights because of the frigid environment. However, the fish that have been appearing are 40 to 50 percent underweight compared to what they should be based on their age and size.
“They move sluggishly and appear almost lifeless in the deep, dark waters just floating around down there and moving around like zombie fish,”
Michigan Department of Natural Resources biologist Shawn Sitar told UpNorthLive.
A tweet from X.
The problem is hitting hard in the deepest spots 180 meters (about 600 feet) and beyond. In some catches, nearly 50 percent of the siscowets look this way. Scientists say the trend has grown steadily over the past decade, with broader drops in growth and condition noted since around 2010.
Healthy siscowets are plump and full of fat. The “zombie” ones have sunken bellies, pale skin, and almost no body fat. They’re the same length as normal fish but weigh dramatically less. The nickname comes straight from biologists watching them on underwater cameras slow, lifeless, and weirdly out of character for these tough deep-water survivors.
As soon as the story broke, U.S. social media lit up. Dexerto’s April 19 post racked up shares and replies packed with zombie-apocalypse jokes, Walking Dead memes, and
“Lake Superior is the new Resident Evil”
Comments. One viral clip even mashed the fish footage with horror-movie sound effects.
What’s Behind the Skinny Fish?
No single cause has been pinned down yet. Michigan DNR and the Great Lakes Fishery Commission are looking at several straightforward possibilities:
- Food limitation fewer prey fish available in the deep, cold waters.
- Disease or pathogens affecting how the trout eat and store energy.
- Sea lamprey impacts even though siscowets are fairly resistant, the blood-sucking invaders can still take a toll.
- Contaminants in the water.
- Broader ecosystem changes in the Great Lakes since 2010.
“It’s likely a combination of factors rather than a single cause,”
Said Great Lakes Fishery Commission Director Greg McClinchey.
Lake Superior is largest freshwater lake in the world by surface area and a cornerstone of the Great Lakes system. Lake trout support commercial fishing, charter boats, and tourism that pump millions into Michigan, Minnesota, and Wisconsin economies every year. When a keystone species like the siscowet starts struggling, it raises red flags for the entire food web and for the families who fish these waters for a living.
A major fish health assessment with Michigan State University is set for June 2026. Field teams will test the “zombie fish” for disease, parasites, and other problems. Scientists hope the results will point to clear fixes so they can protect the population before it worsens.
Lake Superior’s deep waters have bounced back before lake trout were declared fully recovered in late 2024 after decades of work against overfishing and sea lamprey. This latest wrinkle shows how closely we still need to watch America’s freshwater treasures. The “zombie fish” may look spooky, but the real story is about keeping our Great Lakes healthy for the next generation of anglers and families who call the region home. Updates are expected after the June fieldwork.
