ApplawsTuna Fillet Chewy Treats

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.

The familiar white potato, used as a carbohydrate source in many grain-free foods. Potato starch binds kibble; potato protein is a concentrated plant protein that lifts the protein figure on the bag. Cooked potato is safe and well digested. Grain-free foods built on potatoes and legumes were part of the FDA's 2018 to 2022 look at diet-associated heart disease in dogs, which did not establish a cause; the agency has not asked for any to be withdrawn.

Rendered fat, a concentrated energy source and the main supply of linoleic acid, an essential fatty acid for skin and coat. Rendered fat carries very little protein, so many chicken-allergic pets tolerate it, but not all do, and a strict elimination diet avoids it. Usually preserved with mixed tocopherols. Not a quality concern; a good fat source.

Oil pressed from whole fish, usually menhaden, herring or sardine, added as the source of the omega-3 fats EPA and DHA. Those fats support skin, coat, joints and brain development, and a food that names fish oil is delivering them in the form pets use directly. It goes rancid quickly, so look for a preservative named alongside it, usually mixed tocopherols. The species is rarely stated, which matters only if your pet reacts to fish.

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.