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Vegan Fish Food: The Holy Grail Of Trout Farming

Ron Hardy
University of Idaho Aquaculture Research Institute
Rainbow trout are the test fish in a project that aims to develop a plant-based diet for farmed fish. The research effort is headed by Dr. Ron Hardy, Director of the Aquaculture Research Institute at the University of Idaho.

"Vegan" rainbow trout will be the hot topic at this year’s International Symposium on Fish Nutrition and Feeding in Sun Valley, Idaho.

The trout are billed as vegan, but their new menu, developed by the University of Idaho’s Director of Aquaculture Research Ron Hardy, includes a little fish oil. So more accurately, they might be called these pescatarian trout.

“I guess you’re right,” Hardy said. “That would be more accurate, but that’s the only animal or fish product in the diets these days.”

Researchers have been trying get trout to go vegan for decades because it would be the cheapest way to feed farmed fish. Wild trout eat insects, shrimp and smaller fish. So traditionally farmed fish are fed a meal made from other fish.

But Hardy said that’s not sustainable.

“Aquaculture has grown rapidly over the last 25 years -- and now supplies over 50 percent of fisheries products that people consume around the world -- and if we look to the future, at today’s per capita fish intake around the world we would need to double aquaculture production.”

Hardy is selectively breeding trout that can handle feed made from wheat, corn and soybeans. So far they still need omega 3 fatty acids. Hence the added fish oil.

When the project began, it took nearly a year to produce a one-pound trout. These days, the experiment yields trout that grow between two and four times as fast in the same amount of time.

Some of those fish are already selling as part of a small niche market with at least one producer in California.