FISH is a high-protein, low-fat food. It is full of important nutrients, such as protein and vitamin D. It is also the best source of omega-3 fatty acids, which is great for your dog’s joints and mobility. Fish is also beneficial dog’s skin. Fatty fish (like salmon, trout, sardines, tuna and mackerel) are higher in fat-based nutrients. Fish and other seafood are relatively low in saturated fats and empty calories – being good for weight control. Fish is a fantastic source of nutrition for dogs.