Fish Farming in the Arizona Desert Sparks Big Questions About Water Use

Dateland, Arizona — In the heart of the arid Arizona desert, where water is already scarce and under increasing scrutiny, a fish farm is stirring debate. At first glance, it seems improbable: thousands of tropical fish splashing in man-made ponds under the relentless desert sun. But that’s exactly what’s happening at a facility run by Mainstream Aquaculture, an Australia-based company growing barramundi—also known as Asian sea bass—for U.S. restaurants.

They say it’s sustainable. Critics say it’s reckless.

Seafood, But Make It Desert-Grown

Dan Mohring, who oversees day-to-day operations, feeds the fish using a cannon that shoots a blend of ground-up meat and nutrients into the water. Instantly, the surface erupts with hungry barramundi, all destined for dinner plates in a few months.

Mainstream argues that raising fish in the desert can actually reduce the environmental footprint of seafood. By producing domestically, they cut down on emissions from international shipping. Plus, they reuse the nutrient-rich water to irrigate crops like Bermuda grass, which is later sold as cattle feed.

“We’re in the business of water,” said Matt Mangan, who heads the company’s U.S. division. “We want to be here 20, 30 years from now.”

But whether that’s a responsible use of water in a drought-prone state is up for debate.

The Water Problem: Efficient Use or Risky Gamble?

The farm draws from groundwater, not the Colorado River. But that’s hardly reassuring to water experts. Groundwater in Arizona is largely unregulated in rural areas like Dateland and is considered a nonrenewable resource—once it’s gone, it’s gone.

“As long as groundwater is treated as an open resource in these parts of Arizona, they’re vulnerable to industries just coming in and pumping,” said Sarah Porter, director of the Kyl Center for Water Policy at Arizona State University.

And aquaculture is thirsty. Based on the company’s own data, Porter estimates the farm could use as much water as a large ranch—or even a small Phoenix suburb.

Is It Sustainable Aquaculture or Desert Hubris?

Some see potential in aquaculture to ease pressure on overfished oceans and reduce the need to import 80% of U.S. seafood. Others aren’t so sure Arizona is the place to do it.

“Artificial ponds in the desert are stupid,” said Jay Famiglietti, a hydrologist and head of science at ASU’s Arizona Water Innovation Initiative. He points to the massive water losses through evaporation.

Mainstream acknowledges some challenges, particularly in the winter months when pond water loses heat and more water needs to be pumped to maintain the temperature fish need to survive. But they’ve been redesigning ponds to improve insulation and say they’ve cut water use by about 50% in the past year.

They also argue that reusing the wastewater to grow cattle feed adds efficiency—though that comes with its own environmental baggage. “Doing two suboptimal things doesn’t make it better,” Famiglietti said, referring to both aquaculture and supporting the carbon-heavy cattle industry.

What Counts as ‘Reasonable’ Use of Groundwater?

Unlike parts of Arizona that tightly regulate groundwater, Dateland falls outside those zones. The only real rule? Landowners can pump a “reasonable” amount of groundwater. But what’s “reasonable” when it comes to fish farming? Legally, there’s no precedent.

“Whether this is a good use of water depends on what kind of state Arizona wants to be,” said Rhett Larson, a professor of water law at ASU.

Can Farmed Fish Replace Ocean-Caught Seafood?

Many scientists see aquaculture as part of the solution to overfishing, especially if it moves away from using wild fish to feed farmed ones. “We shouldn’t rely on ocean fish to grow fish,” said Pallab Sarker, an aquaculture sustainability expert at UC Santa Cruz.

Still, it’s unclear what exactly goes into the feed used by Mainstream. Mohring and Mangan said their suppliers are Skretting and Star Milling but couldn’t confirm the origins of base ingredients—some of which may still come from wild fish like anchovies and mackerel.

Kevin Fitzsimmons, a University of Arizona professor who mentored the student that started the farm Mainstream acquired, argues the alternative is worse. “We can’t keep hunting and gathering from the ocean,” he said.

Big Ideas, Bigger Trade-Offs

Mainstream hopes to expand by partnering with local farmers to reuse its nutrient-rich wastewater for hay and feed crops. A few have expressed interest.

Still, the broader question remains: Is it wise to raise fish in one of the driest places in the U.S.?

The company sees innovation. Critics see a warning sign. And as Arizona continues to face down climate change and long-term drought, every drop of water—and every decision about how it’s used—counts.