Sardines Sardines are small, soft-boned saltwater fish. They’re usually sold canned in water, oil, or sauces, though you can also buy them fresh. Sardines are super nutritious because they contain virtually every single nutrient in good amounts. A 1-cup (150-gram) serving of drained sardines provides 554% of the DV for vitamin B12 Furthermore, sardines are an excellent source of omega-3 fatty acids, which have been shown to provide many health benefits, such as reducing inflammation and improving heart health.