ApplawsTuna Fillet, Peas & Carrots Recipe 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 staple of grain-free recipes, supplying starch, fiber and plant protein. Peas were common in the diets examined in a federal investigation into heart disease in dogs; the investigation did not establish a cause and no ingredient was banned. Pea protein high on a list can inflate the protein number with a plant source. Pea allergy is rare. Not a problem, but worth noticing when it appears in several forms in one recipe.

A vegetable that contributes a little fiber and beta-carotene and a lot of label appeal. In dry food it is usually present in small amounts well down the list. It is not an allergen of concern and not a meaningful protein or calorie source. Fine to see; not a reason to choose one food over another.

A grain used as an easily digested carbohydrate. White rice has had the bran removed; it digests fast and is the classic bland-diet starch. Brewers rice is the small broken fragments left after milling, nutritionally the same as white rice despite its reputation as a cheap filler. Rice bran is the outer layer, mostly fiber and oil. Grain allergy is rare in pets; rice is one of the least reactive grains.