Fish Oil

Coat changes usually take several weeks to two months to show. Most timing data come from dogs, where skin and coat improved after about four to seven weeks.

Fish oil is oil extracted from fish and is the main source of the omega-3s EPA and DHA in cat food. Tufts veterinary nutritionists explain that omega-3s are linked to compounds that help resolve inflammation, and they warn that too much or too little of either omega-3 or omega-6 fats can have adverse effects. Ask your veterinarian about a cat with a medical condition, especially before adding a supplement.

Source: sites.tufts.edu

Fish oil is added to supply EPA and DHA, two omega-3 fatty acids. Tufts veterinary nutritionists say cats cannot convert ALA, the omega-3 in plants like flax, into EPA and DHA, so fish oil or algae oil is the direct way to include them. The oil also adds fat calories and a fish flavor that many cats accept readily.

Source: sites.tufts.edu

It means the oil came from fish, but the label does not say which kind. It could come from menhaden, anchovy, sardine or a blend of species. Named oils such as salmon oil, herring oil or pollock oil tell you the source. The species can matter to your veterinarian if your cat is on a diet that avoids certain fish.

Some are. The Merck Veterinary Manual lists fish, along with beef and chicken, among the common food allergen sources in cats. Food allergies are reactions to proteins, and oil carries much less protein than fish meat, but labels do not show how much remains. If your cat has a diagnosed fish allergy, your veterinarian can tell you whether foods with fish oil fit its diet.

Source: merckvetmanual.com

Pettings scores fish oil 5 out of 5 and files it as a general cat food ingredient. We found it on 38 of the 149 dry cat foods in our list. The ingredient score is separate from a food's overall score, which you can see on each food's page.