Yellowfin tuna; Chinook salmon; lingcod; Pacific halibut. Chang/iStockphoto; Debbi Smirnoff/iStockphoto; via TeachAGirlToFish; Andrea Pokrzywinski/Flickr hide caption

itoggle caption Chang/iStockphoto; Debbi Smirnoff/iStockphoto; via TeachAGirlToFish; Andrea Pokrzywinski/Flickr

The FDA is recommending that pregnant women eat 8 to 12 ounces per week of fish such as salmon, canned light tuna, tilapia or cod. Iakov Filimonov/iStockphoto.com hide caption

itoggle caption Iakov Filimonov/iStockphoto.com

Carp are collected at a breeding farm near the Belarus village of Ozerny in November 2013. Researchers say there's a lot the aquaculture industry can do to be more efficient. Viktor Drachev/AFP/Getty Images hide caption

itoggle caption Viktor Drachev/AFP/Getty Images

A tuna fishing boat drags a cage of nets on the Mediterranean sea in 2010. (The Mediterranean is not considered to be part of the "high seas.") Andreas Solaro/AFP/Getty Images hide caption

itoggle caption Andreas Solaro/AFP/Getty Images

A marlin caught as bycatch by the California drift gillnet fishery. The conservation group Oceana called the fishery one of the "dirtiest" in the U.S. because of its high rate of discarded fish and other marine animals. Courtesy of NOAA hide caption

itoggle caption Courtesy of NOAA

A fish that knows the way to go: the Chinook salmon, which appears to use the Earth's magnetic field to navigate ocean waters and rivers. Jeff T. Green/Getty Images hide caption

itoggle caption Jeff T. Green/Getty Images

How to make dead fish look attractive? That's the challenge New York-based duo Shimon and Tammar Rothstein faced when they were hired to do the photography for famed French chef Eric Ripert's book On the Line. Photos by Shimon and Tammar, Courtesy of Shimon and Tammar hide caption

itoggle caption Photos by Shimon and Tammar, Courtesy of Shimon and Tammar

Ava Gene's, a Roman-inspired restaurant in Portland, Ore., incorporates colatura, a modern descendant of ancient Roman fish sauce, into several of its dishes. Deena Prichep/NPR hide caption

itoggle caption Deena Prichep/NPR

People hoist the body of an 18-foot oarfish that was discovered in Toyon Bay at Catalina Island off the California coast. Courtesty of Catalina Island Marine Institute hide caption

itoggle caption Courtesty of Catalina Island Marine Institute

A fishmonger tosses a just-purchased fresh salmon to a colleague behind the counter at the Pike Place Fish Market in Seattle. Elaine Thompson/AP hide caption

itoggle caption Elaine Thompson/AP

In a study of 4,000 pregnant women, fish accounted for only 7 percent of blood mercury levels. JackF/iStockphoto.com hide caption

itoggle caption JackF/iStockphoto.com

Colorful covers of menus from the Royal Hawaiian Hotel (left) and the Monarch Room Royal Hawaiian Hotel. New York Public Library hide caption

itoggle caption New York Public Library

Jessica McConnell, 26, of Silver Spring, Md., tries to identify halibut, red snapper and salmon at a dinner hosted by Oceana and the National Aquarium in Washington, D.C. Heather Rousseau/NPR hide caption

itoggle caption Heather Rousseau/NPR

Thierry Chopin from the University of New Brunswick examines a raft that holds strings of seaweed. The seaweed grows around pens of farmed salmon and soaks up some of the nutrients that would otherwise pollute the Bay of Fundy. Richard Harris/NPR hide caption

itoggle caption Richard Harris/NPR

A young parishioner carries plates filled with fried fish and potatoes to a table during a Lenten Friday fish fry at St. Frances Cabrini Catholic Church in Littleton, Colo., in 2009. David Zalubowski/AP hide caption

itoggle caption David Zalubowski/AP

Escolar, right, is often substituted for more expensive Albacore tuna (left), a report on mislabeled seafood found. Yoon S. Byun/Boston Globe via Getty Images hide caption

itoggle caption Yoon S. Byun/Boston Globe via Getty Images