Josh Goldman once spent three years looking for a fish.

No, it wasn’t a Monty Python sketch. Goldman, who had spent years farming striped bass and, before that, tilapia, wanted a better species of fish -- one that didn’t have the bass’ problems, like short fertile periods or a tendency to get stressed when moved from tank to tank. He also wanted one with the health benefits -- namely, heart-healthy omega-3 fatty acids -- of a predatory species, but without the enormous inputs required to raise big, carnivorous fish such as salmon or tuna.

The stakes, globally, are high. With wild fish stocks collapsing -- the U.N.’s Food and Agriculture Organization (FAO) estimates that 32 percent of the world’s ocean fisheries are depleted or overfished, and another 52 percent will become so if they’re pushed beyond present levels -- many people see aquaculture as the best hope for easing pressure on the oceans while still helping meet the growing global demand for fish protein.

But those familiar with the perils of industrial agriculture on land shouldn’t be surprised that fish farming -- currently one of the fastest-growing food industries in the world -- comes with a whole school (ouch) of downsides.