A better way to grow a fish?

By JUDY WEST

Aquaculture—or fish farming—has gotten bad press recently for the high levels of pollution it can create. Leon Weiss, a professor of cell biology in the School of Veterinary Medicine, says it’s not all bad. In fact, he explains, done the right way aquaculture can produce fish that are tastier and healthier to eat than wild fish, and without any bad effect on the environment.

Weiss has been experimenting with aquaculture techniques at Penn’s New Bolton Center. The problem with ocean aquaculture, he says, is that “when you put all of these thousands of fish in large pens and tether them and keep feeding them, they’re going to defecate … and if you don’t husband them correctly, you’ll find the wastes the fish are producing creates algal bloom.” Weiss solves that problem by keeping the fish in a tank where the water is pumped continually through filters where it’s cleaned and restored. “We have exquisite control,” says Weiss. “We can make sure there’s enough oxygen and create the ecology and environment they need.”

According to Weiss, carefully monitored aquaculture can offer consumers healthier fish, too. “Because of commercial dumping of plaster and other building materials, the ocean has a lot of heavy metals,” he says. “Wild fish coming from a polluted ocean may not be an ideal fish to eat.”

With diseases like Mad Cow and Foot and Mouth, says Weiss, hog, beef and poultry farming are becoming increasingly problematic ways to make a living. Weiss sees aquaculture as a viable alternative for some farmers. Pond aquaculture, where existing ponds on a property are used to grow fish, offers a less expensive option for small farmers. At New Bolton, Weiss is experimenting with both re-circulating tanks and ponds—where he’s farming a hybrid striped bass that can live in fresh water—and he hopes to soon set up a retail fish outlet there to test the market and “allow people from Wharton and the Vet School to see what it is to sell a fish.”

One snag, he concedes, is that wild fish tend to taste better than farmed. Weiss is working with the Monell Chemical Senses Center to get an objective evaluation. Some off tastes, he says, are due to a form of plankton that can be removed from the water. “There’s every reason to believe that a farmed fish done properly in the right environment can be even tastier than a wild fish.”