The Lockdown Made Big Fish Bad News

When a restaurant serves a fish whole, there is a reason it fits the plate perfectly. It’s because Boris Musa grew it that way. His indoor fish farm in Australia supplies restaurants with plate-size barramundi grown to 1.8 pounds. The coronavirus put the restaurant industry on ice for months, but Mr. Musa’s fish kept growing. That led to a big fish problem—as in, his fish were getting too big. If Mr. Musa’s barramundi, a white fish popular in Australia, grow too much, the water-filtration system that is keeping them alive won’t be able to keep up. Once they tip the scales at about 3 pounds, he said, they’re too large for a restaurant dinner plate. To save his fish, and his future profits, Mr. Musa is turning to science. He is betting that by lowering the water temperature in his tanks, he can slow down the metabolism of his fish, reduce their appetites and stall their growth. At the height of the lockdown, he even considered a more extreme option: trucking his fish more than 1,000 miles away to a more spacious outdoor farm owned by his company. “This is a really peculiar set of circumstances,” said Mr. Musa, chief executive of MainStream Aquaculture, which spent years breeding fish to grow faster. “Normally in our business, we’re trying to maximize the biological potential of our fish.” Fish farmers all over the world are trying to slow the growth of their fish as the pandemic wreaks havoc on supply chains and consumer demand. Others are trying different strategies: freezing their fish using liquid nitrogen, smoking them so they can be stored until demand returns, and skipping the restaurants and selling their fish online. Restaurants around the world are reopening, but the lockdown created a fish-farm backlog. Fish farming now accounts for almost half of the world’s seafood production. But unlike traditional fishermen, who can stay in port if demand falls, fish farmers who have put time and money into growing their fish can’t just shut down...WSJ