At Cargill Inc.’s research station in Elk River, rows of fish tanks teem with live shrimp and tilapia, scientists closely monitoring what they eat.

Shrimp and tilapia are at the core of the world’s booming aquaculture industry, which is the future of seafood.

“The oceans are tapped out and seafood consumption is increasing rapidly, so production will have to come from farmed fish and shrimp,” said Dave Cook, research director for Cargill’s animal feed business.

Of course, fish need to eat, and that’s an opportunity for Cargill — one of the world’s largest animal feed producers. The aquaculture business is still small compared with Cargill’s feed mainstay, the traditional livestock and poultry industries. But it’s growing about twice as fast.

Animal feed is one of the lesser-known of Cargill’s many businesses, which run from cocoa processing to corn refining and grain trading. Despite its low profile, though, animal feed is one of Cargill’s most global businesses. And it’s poised for steady growth as world demand climbs for protein — via pork, beef, chicken or fish.

“We are definitely a growth engine within the house of Cargill,” said David Webster, president of Cargill’s pre-mix feed and nutrition business.

Minnetonka-based Cargill, one of the world’s largest private companies, doesn’t break out financial details on its businesses. However, the animal feed business has 17,000 employees in 37 countries, and its sales are measured in billions of dollars. That makes it a significant center for Cargill profits.

The company has two global feed research centers, one in the Netherlands and the other in the northwest suburb of Elk River. The 800-acre local campus, which employs 120, features labs for cows, laying hens, pigs and fish. Researchers tinker with ingredients and feed ­formulas, looking for combinations that will optimize meat, egg and fish production.

For fish and shrimp, the Elk River lab is looking for ways to cut the amount of fishmeal in feed without compromising nutrition. Fishmeal is a key protein source. It’s made from ground fish such as anchovies, and just like wild-caught fish intended for human consumption, there are generally natural limits on supply.

But other protein sources — soybean meal and animal byproduct meals — can be used to reduce our reliance on finite resources like fishmeal.

The world’s animal feed business is highly fragmented, and global players like Cargill compete with a lot of regional feed producers. Aquaculture is no different.

Thirty-five percent of the aqua feed market is divided among four global companies, none of which has more than a 12 percent market share, said Reuben Sequeira, an analyst at Frost & Sullivan, a research and consulting firm. Cargill isn’t ranked in Frost & Sullivan’s top five, but its world share is estimated at up to 3 percent.

Aquaculture makes up only about 8 percent of the global animal feed business, which is led by poultry, Sequeira said. But the fish feed market is growing at about 9 percent annually.

Cargill’s aquaculture business would have gotten a big boost if the company had prevailed in a recent multibillion-dollar attempt to buy Dutch feed giant Nutreco. In November, Cargill made a joint bid for Nutreco with British private equity firm Permira Advisers. Cargill planned to take Nutreco’s aquaculture business, Permira the rest of the firm.

Nutreco squelched Cargill’s bid because it would have split the company in two, and instead sold itself to another Dutch company for close to $4 billion. Nutreco’s aquaculture feed business, Skretting, is the second-largest global aquafeed player, according to Frost & Sullivan.

Centered in Asia

Aquaculture includes myriad marine creatures, including salmon, catfish, sea bass, oysters and mussels.

Carp makes for big crops in Asia, though it’s a low-value fish that’s not on Cargill’s radar. Tilapia is the most widespread farmed fish, raised in 135 countries, according to the United Nations’ Food and Agriculture Organization (FAO). Shrimp is the largest aquaculture commodity in terms of monetary value.

The aquaculture business is centered in Asia, particularly in China. The continent accounts for 88 percent of world aquaculture production by volume, an FAO report says. China alone comprised 62 percent of global output in 2012.

Between China, India and Indonesia, “there are a lot of coasts, and a lot of people,” Sequeira said.

For Cargill, Latin America is also a particular hot spot, the region where the company has its largest presence in shrimp feed.

Cargill sells fish feed in the United States. But the U.S. aquaculture business is a bit player on the global stage, accounting for less than 1 percent of world farmed fish production in 2012, according to the FAO. U.S. seafood demand is strong, though, so the country — along with Japan — is one the world’s two largest importers of fishery products.

“Almost anything we buy in the supermarket, odds are it is from overseas and odds are it came from aquaculture,” said David O’Brien, deputy director of aquaculture for the National Oceanic and Atmospheric Administration. “Most people believe that aquaculture is currently producing half of the [global] seafood supply.”

That share will only grow. The world’s wild fisheries plateaued in the 1980, but global seafood demand has risen “dramatically” in the past 20 years, O’Brien said. “Any new seafood has to come from aquaculture.”

Indeed, with the industry’s bright prospects, Cargill may move beyond fish feed directly into operating fish farms.

There’s certainly a precedent. When it comes to poultry, beef and pork, Cargill starts with feed, but also does a huge business in slaughtering and processing animals. Why not the same model in aquaculture?

“At this point, we don’t rule anything out, ” said Cargill’s Webster. “We are looking at the industry and where we can play, and that may include processing.”