Oily fishes such as herring, salmon, sardines, mackerel and anchovies are bursting with omega-3 fatty acids. Omega-3s do wonders for skin, coat and brain as well as limit inflammatory processes that cause arthritic pain and other chronic canine conditions. (If your dog has any of these conditions, ask your vet if fish oil in capsule form might help too.) Fish are an excellent protein source, with many essential vitamins and minerals.