What About Canned?
When the supermarket fish counter fails you, don’t hesitate to head for the canned-fish aisle. Canned sardines and salmon are generally sustainable choices; canned tuna, while controversial, typically includes sustainable pole-caught albacore or skipjack varieties.
Many of the varieties most often canned or preserved in handy pouches are the same fish highest in omega-3s, notably salmon and albacore ("white") tuna. Omega-3s aren't destroyed in the canning process, so you're not sacrificing heart health for convenience. If fish are canned in oil, however, some of the omega-3 fats can migrate into the surrounding oil, to be lost when the fish are drained. That's another good reason to prefer water-packed fish: Albacore tuna canned in oil loses three-fourths of its omega-3s compared to water-packed - while gaining half again as many calories.
Although canning does damage fragile nutrients such as vitamin C, most of the healthy ingredients in fish come through unscathed. Some types of canned fish - sardines, salmon and mackerel, but not tuna - actually outdo the fresh or frozen alternatives in calcium because they're canned with the bones. (The heat of cooking and canning makes the bones soft enough to eat.)
Another advantage to canned fish is it has a long shelf life relative to fresh, making it perfect for a quick meal.