Happy fish taste better, so scientists gave them weed to see if they’d relax

By Scott Berson

Farm-raised Atlantic salmon move across a conveyor belt as they are brought aboard a harvesting boat near Eastport, Maine.
Farm-raised Atlantic salmon move across a conveyor belt as they are brought aboard a harvesting boat near Eastport, Maine. ASSOCIATED PRESS file

Being a fish can be stressful, but it can be especially stressful if you’re a farm fish.

Farm-raised fish are packed into cages at much higher densities than they would be in the wild, leaving them with poorer water quality, a higher incidence of disease and a greater chance they’ll fight among each other, reported Hakai. Even pet fish can be stressed and depressed by their small surroundings just as humans would be, Jullian Pittman, a professor at the Department of Biological and Environmental Sciences at Troy University told the New York Times.

The neurochemistry is so similar that it’s scary,” he said, “But there s a lot we don’t give fish credit for.”

All that stress and unhappiness isn’t just bad for the fish’s quality of life - it’s bad for business too. Fish facing excessive stress can get sick or even die, which is one less animal sold for the farmer, according to a new study published in Aquaculture Research.

Some simply appear to give up, floating slowly around the edges of the pools, not growing or eating. Scientists in Norway took measurements of hormones in those fish’s bodies and found high levels of chemicals like cortisol that are related to chronic depression in humans, reported

Stress isn’t great for the taste either. In a 2011 study published in the Journal of Food Science, researchers explained how stress in fish can lead to a constant buildup of lactic acid in the muscles, which spikes even higher before slaughter. This makes the fish rigid and hard to process, the researchers explained. It can also lead to a bitter taste and rancid smell, according to a study published in Science.

None of that is good for the fish, the farmer trying to sell the fish nor the consumer who wants to eat the fish.

Part of the problem can be solved by killing fish more quickly and eliminating the spike in stress right before slaughter, according to the study published in Science, but that still leaves a long time in the farm where the fish may be unhappy. That’s why scientists decided to try an unconventional approach to promoting fish happiness - getting them high.

The study, published in the journal Aquaculture Research, involved giving farm-raised Nile Tilapia one of three diets: one containing soy oil, one of hemp oil and one of cannabis oil. Cannabis oil is thought to reduce stress, and is sometimes used in humans to treat post-traumatic stress disorder and other medical problems, the Associated Press reported. If it makes humans relax, maybe it would make the fish relax too.

The researchers kept the fish on those same diets for eight weeks, measuring things like blood cell counts, plasma protein and other factors that can give a picture of a fish’s general stress and health levels.

So did it work?

Well, it did something. Although the fish didn’t appear to be any healthier or happier after the study concluded, the researchers noted that their metabolisms had increased, so they ate and digested food more quickly - a case of the fish munchies, you could say.

“Until further research yields different results, we do not believe fish should be given reefer,” the study authors concluded, Hakai reported.