These are  single-ingredient treats made from the skin of cod fish. Cod skin is rich in protein and omega-3 fatty acids, which are great for your dog's skin and coat health. Plus, the crunchy texture can help reduce plaque and tartar buildup on their teeth. These treats are often dehydrated or air-dried to preserve their nutrients and give them a longer shelf life. Many brands pride themselves on using ethically sourced, wild-caught cod.