ApplawsTuna Fillet & Salmon in Broth

A fish used mostly in cat foods, where its strong flavor is the point. Tuna is a good protein and a source of omega-3 fats. Two cautions apply to tuna fed often: it is higher in mercury than smaller fish, and cats can become fixated on it and refuse other foods. Both cautions apply to the cat eating tuna every day, and much less to tuna as one ingredient in a complete food fed in rotation.

Fish with no species stated. The maker may use whatever is available, so the fish can change between batches. Nutritionally it is a fine protein and often a source of omega-3 fats. The gap is for pets with a known fish allergy, or whose owners are trying to track which protein causes a reaction, because an unnamed ingredient makes that very hard. Named fish such as salmon or whitefish give you that information.

A fatty fish used as a protein source and as a natural source of omega-3 fats. Fresh salmon is mostly water, so a salmon meal lower on the list may be contributing more protein. Salmon is a common alternative protein for pets that react to chicken or beef, though fish allergies exist too. Farmed and wild salmon differ in fat profile, and labels rarely say which.