BALTIMORE —
The Baltimore harbor turned green on Friday as hundreds of dead fish and crabs rose to the water's surface in Canton, Fells Point and Locust Point.
The Maryland Department of the Environment said it is all because of the weather.
"I noticed that there was just a bunch of dead fish all of a sudden," said Lucas Hayes, who works in Locust Point.
An MDE investigator saw at least 200 dead crabs and 100 dead fish on Friday, the agency told 11 News.
MDE said the fish kill is a result of low oxygen from a lack of sunlight.
"I didn't really notice them until my sister told me, but there's a lot, and they're just floating up on the shore, on the rocks," said Brittany Tremble, a Canton resident. "There's plenty of them."
Tremble and her sister, Empress, also noticed dozens of fish floating to the surface at Canton Waterfront Park.
"That's insane," said Empress Tremble. "Honestly, I didn't expect to see that many. A little bit of a tragedy, I think."
In addition to the dead fish and crabs, green residue was in the water — but unnoticeable at ground level.
The MDE, National Aquarium and Waterfront Partnership of Baltimore told 11 News it's called a pistachio tide — it's a result of no oxygen in the water at the surface.
In Baltimore, the green coloring typically comes in the fall when it's hot during the day but cold at night, bringing sulfur bacteria from the bottom of the harbor to the surface. It creates an unstable environment for the wildlife.
The MDE is worried about the green tide spreading along the entire coast of Maryland in the coming days, and possibly even other states.
Looks like the fish kill got worse overnight as hundreds of fish washed onto the sidewalk along the harbor right by the aquarium.@wbaltv11 pic.twitter.com/5FoCNSwIp9
— Jake Shindel (@JakeShindel) August 23, 2025
"That's crazy. Because that's their habitat, they should be able to survive in the water," Brittany Tremble said.
"I've seen it before, so I guess it's just something you have to deal with," said Ranell Toland, a Fells Point resident.
"It sucks for the crab, but I guess it's just nature doing nature," Hayes said.
It isn't the first time a pistachio tide has appeared in the harbor. MDE said something similar happened in September 2024, and it was also the result of temperature fluctuations.