calcium can canned clupeidae edible fatty-acids fish food health healthy heart-healthy herring-family nonperishable nutrient-rich nutrients nutritious oil oily-fish omega-3 packed pilchards portable potential sardines self-contained-food small tightly-packed tin tinned tins vitamins roe accessible brisling bristling crammed European-sprat herring-like marine-fish open opened silvery skin skipper sprat sprattus-sprattus tight