The phrase “green trout” has long been a euphemism for marsh bass, but it turns out speckled trout really can turn green — or it seems at least remotely possible, according to a biologist who reviewed a photo posted in the LouisianaSportsman.com reports section.

Website user Web Foot Slayer posted a picture of what appears to be a green-headed speckled trout he said was caught in Bay St. Louis, Miss.

While admitting the possibility that the photo was a prank, retired LSU biologist and Louisiana Sportsman contributor Jerald Horst reviewed the picture and said the fish’s unusual coloration was likely the result of a genetic condition. 

“Odds are what you’ve got is either a genetic morph, or it has to do with water color and clarity — although I doubt very seriously that’s the case,” said Horst, who retired as a professor of fisheries with the LSU School of Renewable Natural Resources.  “I’ve seen a number of fish out of fresh water, but they don’t really turn color.”

Some forum posters commenting on the photo, like Dr. Spot and Capt.-Mike, speculated that the fish might have acclimated to fresher water and changed color, but Horst said that wasn’t the probable cause of the peculiar coloration. 

“More than likely, it’s genetic rather than environmental,” Horst said. “I have not seen salinity have an effect on the color of pretty much any fish. Water clarity and water color does. In a speckled trout that comes out of really clear water — which is often low salinity — their colors that are there are enhanced. They become a blackish silver.”

But Horst said even being in darker water typically wouldn’t entirely change the color of a fish — from silver to green, in this case.

“Tannic water will make a redfish redder, a bass (which is already green) will be greener and darker, and all the multiple colors on a bluegill will be stronger and darker,” Horst said. “But tannic water does not change color as much as it enhances and darkens the pigments already there.

“In answer to your questions, tannic water never makes a fish openly green like this one. But it is darker, as well, so I guess anything is possible. Just because I have never seen or heard of it, doesn’t mean it can’t exist.”

Web Foot Slayer, who posted the picture but didn’t respond to an email request to be interviewed for this story, indicated in comments attached to the photo that he declined to eat the fish because of its strange appearance — but Horst said it was very likely edible.

“Pigment has nothing to do with edibility,” Horst said. “The truth is very little does — and the kind of stuff that would affect edibility you’d never see. If the fish was loaded in mercury, you’’d never see it.

“Stuff that’s full of parasites you’d see, but they’re edible because cooking kills parasites.”

So the question remains: Is this photo legit? What do you think?