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Fish Feeding Guide


Fish is an excellent source of protein rich in Omega-3 fatty acids, which have health benefits like antioxidants and anti-inflammatory properties, aiding your dog’s joints and all round mobility. Fish is also known to have beneficial properties for your dog or cat's skin, fur, heart, and brain. It is relatively low in saturated fats, making it a brilliant source of nutrition alongside other meat proteins. The best two Omega-3 fatty acids for dogs and cats, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are found in the oils of fatty fish.


Feeding small oily fish like sardines, smelt, herring, and mackerel provide the necessary amount of Omega-3. Fish should be the last protein to be fed in the transition, followed by eggs. Carnivores, like cats and dogs, are high-density lipoprotein mammals, meaning they can tolerate high dietary fat concentrations but even then it should be introduced slowly to begin with or you might see it reappear out the other end!

It is recommended that dogs need 300mg of Omega-3 EPA and DHA per 30 lbs (13.6 kg) of body weight. Feed total weight of fish, based on weight of cat or dog.

Amounts to feed per week:

• Small dogs and cats - 33g (1.2 oz) of small oily fish per 10 lbs (4.5kg) of body weight

• Medium to large dogs - 100g (3.5 oz) of small oily fish per 30 lbs (13.6 kg) of body weight

When feeding fish, provide total amount spread over one week or as a whole meal, once a week. If the amount meets your pet’s allowance for a meal you may feed as is. If it does not meet a meal’s allowance for the day supplement the remainder of the meal with meat, bone, and organs.


Fish can be fed as a topper and not included in your pet’s allowance if there is no concern for weight gain. If there is a concern or your pet is on a weight loss journey, deduct the fish from the meat portion of the meal.

Whole fish can be fed but is not necessary. Headless and gutted fish provide the same Omega-3 nutritional value. Some portions, like fish heads, can be bone heavy and might require a reduction of bone in the meal, or a day of boneless meals before or after. Watch for poop and adjust accordingly. Sometimes dogs and cats don't like the texture of fresh fish. If they refuse it this way, try either mixing it with other proteins or feeding it frozen.

Key things to remember: 

  • Fish with high or moderate levels of mercury should be avoided.

  • Fish that is moderate in Omega-3 may not meet the necessary requirements if a diet low in Omega-3 proteins, like grain fed chicken and beef, is fed.

  • Avoid storing fish that contain thiaminase alongside fresh meat as these fish can deplete thiamine in the surrounding meat. These fish are: smelt, anchovy, mackerel, Atlantic herring, and sardines.

  • All fresh fish needs to be frozen for 3 weeks before feeding to kill any potential parasites.

  • If you are unable to source fresh fish you may feed fish in the way of canned such as sardines. Be sure they are canned in water with no salt added.​

Another way to obtain Omega-3 between fish days, if feeding moderate content Omega-3 fish, or as an alternative to fresh fish (if not able to source) is by using Fish oils like Salmon oil, Sardine oil, Krill Oil or even Squid oil. For more information on supplementing with oils, and how the use of supplements can affect Vitamin E please refer to our Fish oil and Vitamin E files.

Fish feeding for Cats:

Thiamine (vitamin B1) is an essential vitamin for obligate carnivores and they must obtain it from the environment because they are unable to produce sufficient amounts. A raw diet provides the necessary amount of thiamine. Some raw fish, however, contain thiaminase which depletes thiamine. So as long as the cat’s diet is well varied with thiamine rich foods like liver and heart, feeding fish containing thiaminase sparingly will not cause a B1 deficiency, only if fed in excess. Cooking, and the process of tinning fish destroys thiaminase alongside thiamine but does not destroy the Omega 3’s.

However, cooking also destroys other water soluble Vitamins and amino acids like taurine, which is also essential to cats. Cooked and tinned, small, oily fish can be fed as a source of Omega-3, but will void the fish of all the other nutrients. Thiaminase can be destroyed by heating fish to 180˚ F (82˚C) for a minimum of five minutes and is only recommended with boneless fish. When feeding tinned fish ensure that no sodium has been added to the product. Avoid all tinned fish in vegetable oil. We recommend, when possible, providing fish raw that do not contain thiaminase, but if unable to source, you can feed fish tinned in water with no added salt or cooked, boneless fish. Do not feed fish if your cat has kidney issues.

Fish that DO NOT contain thiaminase and are OK to feed raw are:

  • Atlantic salmon

  • rainbow trout

  • lake trout

  • lake herring

  • Atlantic mackerel

  • sprats


Fish that DO contain thiaminase are:

  • smelt

  • anchovy

  • mackerel

  • Atlantic herring

  • sardines 

The fish that do contain thiaminase can be fed raw sparingly along side fish that do not contain thiaminase. These fish are also the only ones that should be fed tinned or cooked in relation to ​thiamine for cats. 

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