Ingredient file // Fat or oil
Fish Oil
Useful omega-3s, but the dose stays hidden
Fish oil is fat separated from whole fish or fish processing trimmings. It supplies EPA and DHA, which dogs absorb and which have shown modest benefits in some joint trials. The ingredient name reveals neither the fish species nor the EPA and DHA dose.
Role in the food Supporting nutrient
- What it is
- Oil separated from fish tissue, supplying dietary fat and varying amounts of the omega-3s EPA and DHA.
- Made from
- Whole fish or fish processing trimmings
- Main job
- EPA and DHA source
- Typical amount
- Not published
- Watch for
- Oil that oxidizes during storage
- Not the same as
- Fish meal
Straight answer
Is Fish Oil safe for dogs?
Look for an EPA and DHA amount
Fish oil low on the list is a purposeful fat addition, but its position gives no usable EPA or DHA dose. Read the ingredients above it to judge the main recipe. If omega-3 content matters to you, look for an EPA and DHA guarantee or ask the maker for the amounts.
- Why it is in the food
- EPA and DHA source
- Watch for
- Oxidized oil; Extra oil on top
Our read // In our catalog
In 1 of every 5 foods we track
Share of foods that list it
21%
665 of the 3,204 foods with an ingredient list on file, from 44 brands. 449 dry dog food, 164 wet dog food, 22 frozen dog food.
Each square is 1% of the catalog
Where it sits on the label
Median position 13. In the top five of 7 foods, so it is usually a minor ingredient.
Above the salt
Listed before the salt in 71% of foods. In the rest it is under about 1% of the recipe.
Price per lb
Median of the cheapest bag price across 403 priced foods, about level with the catalog. The price is the food's, not the ingredient's.
Who leans on it
23%
of the foods that list it are from Royal Canin. 44 brands use it in total.
The story
From lamp fuel to a puppy food omega-3 minimum
Much of the US fish oil story runs through the Atlantic menhaden, a small, oily, herring-like fish of the East Coast. Native Americans used it to fertilize crops, and European settlers rendered it into fuel for lamps. Better processing in the mid-19th century expanded the industry, sending the oil into paints and the solids into fertilizer. A reduction plant on Cockrell Creek in Reedville, Virginia, has run continuously since 1878.14,15
Feed came next. After vitamin B12 was found in menhaden, its protein moved into animal feeds, and the industry grew again after World War II. Today Virginia is the last place on the East Coast where menhaden is cooked to extract oil. The omega-3 rich oil goes into supplement pills, and the cooked, pressed remains become pet food or fertilizer.14,15
Researchers later tested the fats in dogs. In a 1998 trial, dogs with surgically reduced kidney mass kept better kidney function on menhaden oil than on safflower oil. In 2005, a separate team reported that puppies fed preformed DHA through pregnancy, nursing and weaning built more plasma DHA and had stronger retinal responses than puppies fed plant omega-3.18,19
Today AAFCO recommends at least 0.05% EPA plus DHA on a dry matter basis in foods for growth and reproduction, and sets no minimum for adult maintenance. The National Research Council puts the safe upper limit for dogs at 280 mg of EPA plus DHA per 100 kcal. Concentrated supplements are treated as therapeutic. That wide gap between a puppy recommendation and a treatment dose is why the words fish oil on a label say so little.16
What it is
How it is made
Fishmeal plants process whole fish and trimmings left by seafood processors. Cooking releases oil from the tissue. The plant separates that oil from water and solids, then turns the solids into fish meal.7,8,9
- 01 // Source Fish and trimmings Whole fish or cuttings from seafood processing arrive at a plant that makes fish meal and oil.
- 02 // Process Cooked and pressed Heat releases oil from fish tissue, and pressing squeezes liquid away from the cooked solids.
- 03 // Process Oil separated Centrifuges separate the oil from water and fine solids in the pressed liquid.
- 04 // Output Fish oil The separated oil goes to feed makers as a fat ingredient that needs protection from oxidation.
What is in it
Composition, dry matter
10-30
% EPA+DHA
The approximate share of these fats in unmodified fish oils. The ingredient name alone cannot tell you how much reaches the bowl.
Benefits
What it does for your dog
Each benefit carries the same evidence grade as the claims below.
-
01
Better retinal development in puppies
Fish oil supplies preformed DHA. In one trial, puppies fed marine DHA built more blood DHA than puppies fed plant omega-3, and at 12 weeks the high marine group had stronger retinal responses.19
- Strong
- Some
- Thin
- None
-
02
Easier movement in arthritic dogs
In a 90-day trial, a joint food high in fish oil omega-3s improved weight bearing in arthritic dogs. That food stated a high dose; an ordinary food listing fish oil promises nothing comparable.17
- Strong
- Some
- Thin
- None
Why it is in the bag
A real omega-3 source, in unstated amounts
- Main nutrition
- Supporting nutrient
- Does a job
- Mostly filler
Makers add fish oil for EPA and DHA, omega-3s that dogs absorb and that AAFCO recommends in puppy foods. It often sits partway down the list, so it is present in smaller amounts than the ingredients listed above it. That position cannot tell you whether the amount is small or a joint diet dose of 160 to 340 mg per 100 kcal. Blood levels track the amount fed; only an EPA and DHA guarantee states it.1,12,16
-
01
Supplies EPA and DHA
Dogs absorb these fats. In a controlled feeding trial, blood EPA and DHA rose as their concentrations increased in the food.1
-
02
Adds dietary fat
Fish oil contributes energy without protein or fiber. Fish meal supplies protein, so the two ingredients do different jobs.5,9
-
03
Uses the processing stream
The same cooked fish yields oil and meal. Recovering oil gives fish processors another saleable product when the raw material contains enough fat.7,8
How much One trial tested complete foods containing 0.8 to 2.9% EPA plus DHA on a dry matter basis, not a usual fish oil amount.1
Our read // The claims
What the evidence supports
Strong: controlled studies in dogs agree. Some: small or mixed dog data. Thin: mechanism or lab work only. None: nothing, or the evidence points the other way.
-
Brands say
Fish oil raises a dog's EPA and DHA
Evidence
- Strong
- Some
- Thin
- None
In a randomized trial of 177 dogs, blood EPA and DHA rose with their concentrations in the food. A separate fish oil trial also measured rising blood levels. The ingredient list still gives no dose.1,2,12
-
Vets say
Fish oil eases arthritic joints
Evidence
- Strong
- Some
- Thin
- None
A 177-dog trial found modest improvements at its highest EPA and DHA level. An independent 77-dog trial found no significant difference from corn oil on its main outcomes. A routine fish oil listing does not promise a treatment dose.1,2
-
Brands say
DHA from fish oil makes puppies smarter
Outruns the evidence
Evidence
- Strong
- Some
- Thin
- None
A 12-puppy trial found better results on one learning task after a measured DHA-rich supplement. That small result does not show that any puppy food listing fish oil improves learning.4
-
Brands say
Fish oil cures itchy skin
Outruns the evidence
Evidence
- Strong
- Some
- Thin
- None
A 16-dog trial found less itching with a measured marine oil supplement than with corn oil. Another diet trial combined EPA with GLA. Neither tested a cure, and neither shows an effect from the undisclosed amount in ordinary food.3,13
-
Owners say
Fish oil on the label means mercury exposure
Outruns the evidence
Evidence
- Strong
- Some
- Thin
- None
A study of pet food ingredients found no mercury above its detection limit in the fish oil samples tested. That does not certify every supplier, but the ingredient name alone is not evidence of exposure.11
The research
Studies worth knowing
Published research we read for this page, dog studies first.
-
2010 // Feeding trial, 2 foods
Arthritic dogs bore more weight on a fish oil food17
38 client-owned dogs with osteoarthritis at 2 university clinics
Found. Dogs ate a regular commercial food or a test food with 3.5% fish oil omega-3s. Over 90 days, force plates showed better weight bearing in 82% of test food dogs versus 38% of control dogs.
What it means. A joint food with a stated high omega-3 level helped within 3 months. A plain fish oil listing does not tell you the dose.
-
1998 // Feeding trial, 3 fats
Menhaden oil slowed kidney decline in dogs18
21 dogs with surgically reduced kidney mass
Found. Groups of 7 dogs ate a diet with 15% added fat from fish oil, safflower oil or beef tallow for 20 months. Kidney filtration averaged 1.43 ml/min/kg on fish oil versus 0.89 on safflower oil.
What it means. This was a lab model at a very high fish oil dose. It explains why kidney diets add fish oil, not what a regular food does.
-
2005 // Feeding trial, 3 diets
Puppies fed marine DHA had stronger retinal responses19
Puppies whose mothers ate the test diets through pregnancy and nursing
Found. Puppies fed preformed DHA built more blood DHA than puppies fed plant omega-3. At 12 weeks, the high marine group had the best retinal tests and the low omega-3 group the poorest.
What it means. Plant omega-3 is a weak stand-in for fish DHA in puppies, so the fat source in a puppy food matters.
Straight answers
What owners ask
-
Q01
Is it just filler?
NoIt adds fat and supplies EPA and DHA. Dogs fed measured amounts showed increases in those fats in their blood. Its place on the ingredient list cannot tell you how much it supplies.1,5,12
-
Q02
Can I tell which fish?
Not hereThe name fish oil does not identify a species. Published herring and salmon oil figures differ substantially. A named source tells you more about origin; an EPA and DHA guarantee tells you more about the dose.6,12
-
Q03
Does it mean mercury?
NoFish oil samples in one pet food ingredient study had no mercury above the test's detection limit. The result applies to those samples, not every supplier. A fish oil listing is not a mercury measurement.11
Who uses it
Brands, best sellers and the company it keeps
Top brands, by foods that list it
Foods that list it / all the brand's recipes we track.
Plus 34 more brands.
Amazon best sellers that list it
- #9 Purina Pro Plan Adult Sensitive Skin & Stomach Salmon & Rice Formula Dry Dog Food
- #20 Purina Pro Plan Adult Small Breed Shredded Blend Chicken & Rice Formula Dry Dog Food
- #23 Purina Pro Plan Adult Sensitive Skin & Stomach Small Breed Formula Dry Dog Food
- #26 Purina Pro Plan Puppy Chicken & Rice Formula Dry Dog Food
- #27 Blue Life Protection Formula Senior Chicken and Brown Rice Recipe Dry Dog Food
- #29 Royal Canin Small Adult Dry Dog Food
- #30 Blue Life Protection Formula Puppy Chicken and Brown Rice Recipe Dry Dog Food
- #33 Purina One SmartBlend Sensitive Systems Formula Adult Premium Dry Dog Food
Rank on Amazon's dog food best seller list, checked October 2026.
Usually listed with, share of the foods that list it
- Chicken 46%
- Natural Flavor 46%
- Chicken Fat 42%
- Brewers Rice 29%
- Mixed Tocopherols 27%
- Brown Rice 27%
- Dried Plain Beet Pulp 26%
- Chicken By-Product Meal 22%
- Chicken Meal 21%
- Flaxseed 21%
- Wheat Gluten 19%
- Peas 18%
On the shelf
Foods that list Fish Oil
665 foods in our catalog list it. These 60 list it highest on the label.
Vital EssentialsVital Essentials Duck Soft Nibs Freeze-Dried Dog Food
Vital EssentialsVital Essentials Duck Mini Patties Freeze-Dried Dog Food
BlueBlue True Solutions Mobility Support Wet Dog Food
WeruvaWeruva Dogs in the Kitchen Puppy Chicken Formula in Gravy Wet Dog Food
AuthorityAuthority Sensitive Stomach & Skin Shreds in Broth Adult Dog Meal Dog Food Topper
WeruvaWeruva Dogs in the Kitchen Puppy Chicken & Rice Formula in Gravy Wet Dog Food
The Honest KitchenThe Honest Kitchen Functional Pour Overs: Hip & Joint - Chicken Stew Dog Food Topper
Simply NourishSimply Nourish Natural Solutions Skin & Coat All Life Stage Dog Meal Dog Food Topper
BlueBlue Basics Grain Free Adult Duck Potato Recipe Wet Dog Food
Royal CaninRoyal Canin Veterinary Multifunction Renal Support + Hydrolyzed Protein Dry Dog Food
Royal CaninRoyal Canin Veterinary Hydrolyzed Protein PS Grain-Free Dry Dog Food
Hill'sHill’s Prescription Diet k/d + Mobility Kidney + Joint Care Chicken Flavor Dry Dog Food Show 48 more
Vital EssentialsVital Essentials Entrée (Nibs) Chicken Nibs Freeze-Dried Dog Food
Vital EssentialsVital Essentials Raw Entrées Duck Entree Patties Frozen Dog Food
AcanaAcana Singles Limited Ingredient Diet Lamb & Apple Recipe Grain-Free Dry Dog Food
BlueBlue Life Protection Formula Homestyle Recipe Grain-Free Senior - Chicken & Garden Vegetables Wet Dog Food
WholeHeartedWholeHearted Gravy Puree Lamb Recipe in Gravy Dog Meal Dog Food Topper
IamsIams Proactive Health Puppy With Chicken AND Rice Classic Ground Wet Dog Food
Royal CaninRoyal Canin Canine Care Nutrition Sensitive Skin Care Loaf in Sauce Wet Dog Food
Simply NourishSimply Nourish Original Puppy Wet Dog Food
PurinaPurina Beneful Freshly Prepared Stews Chicken Dinner with Carrots and Rice in Gravy Wet Dog Food
BlueBlue Freedom Puppy Grain Free Chicken Recipe Wet Dog Food
EukanubaEukanuba Premium Performance 21/13 Sprint Dry Dog Food
AcanaAcana Wholesome Grains Limited Ingredient Diet Lamb & Pumpkin Recipe Dry Dog Food
WeruvaWeruva Awesome Functions Awesome Shiny Chicken & Rice For Skin & Coat Health Wet Dog Food
WeruvaWeruva Awesome Functions Awesome Bouncy Chicken Breast & Riceberry Recipe with Veggies, Turmeric & Ginger Wet Dog Food
WeruvaWeruva Awesome Functions Awesome Bouncy Chicken & Riceberry For Joint Health Wet Dog Food
Hill'sHill’s Prescription Diet d/d Salmon Skin Care Wet Dog Food
Royal CaninRoyal Canin Comfort Care Loaf in Sauce Wet Dog Food
Royal CaninRoyal Canin Starter Mother & Babydog Ultra Soft Mousse In Sauce Wet Dog Food
Diamond CareDiamond>Care Diamond Care Sensitive Stomach Formula Grain-Free Dry Dog Food
PedigreePedigree Puppy Chopped Ground Dinner, Chicken & Beef Wet Dog Food
PedigreePedigree Puppy Chopped Ground Dinner Can, Lamb & Rice Wet Dog Food
Royal CaninRoyal Canin Breed Health Nutrition French Bulldog Loaf In Sauce Wet Dog Food
Simply NourishSimply Nourish Skin & Coat Recipe Adult Wet Dog Food
PurinaPurina Beneful Freshly Prepared Stews Turkey Dinner with Spinach and Ditalini Pasta in Gravy Wet Dog Food
BlueBlue Baby Blue Puppy Turkey Potato Wet Dog Food
BlueBlue Wilderness Puppy Food - Turkey & Chicken Grill Wet Dog Food
IamsIams Advanced Health Mobility Support Dry Dog Food
Royal CaninRoyal Canin Veterinary Selected Protein PW Grain-Free Dry Dog Food
Royal CaninRoyal Canin Veterinary Early Cardiac Dry Dog Food
Royal CaninRoyal Canin Veterinary Selected Protein PD Grain-Free Dry Dog Food
Royal CaninRoyal Canin Veterinary Selected Protein KO Dry Dog Food
Royal CaninRoyal Canin Veterinary Renal Support F Dry Dog Food
Royal CaninRoyal Canin Veterinary Renal Support A Dry Dog Food
Royal CaninRoyal Canin Veterinary Selected Protein Adult PV Dry Dog Food
Royal CaninRoyal Canin Veterinary Hydrolyzed Protein Moderate Calorie Dry Dog Food
Royal CaninRoyal Canin Veterinary Satiety + Hydrolyzed Protein Dry Dog Food
Hill'sHill’s Prescription Diet j/d Joint Care Small Bites Chicken Flavor Dry Dog Food
Royal CaninRoyal Canin Shih Tzu Puppy Dry Dog Food
Royal CaninRoyal Canin Setter Adult Dry Dog Food
DiamondDiamond Care Sensitive Stomach Formula for Adult Dogs Grain-Free Dry Dog Food
Royal CaninRoyal Canin French Bulldog Adult Dry Dog Food
WeruvaWeruva Awesome Functions Awesome Shiny Beef & Brown Rice Recipe with Flaxseed Wet Dog Food
PurinaPurina Pro Plan Puppy Small Breed Chicken & Brown Rice Entrée Wet Dog Food
Vital EssentialsVital Essentials Soft Nibs Beef Freeze-Dried Dog Food
Royal CaninRoyal Canin Shih Tzu Loaf In Sauce Wet Dog Food
WeruvaWeruva Dogs in the Kitchen Puppy Beef & Rice Formula in Gravy Wet Dog Food
Royal CaninRoyal Canin Veterinary Canine Renal Support Early Consult Dry Dog Food
PedigreePedigree Puppy Pouch, Beef Wet Dog Food Sources
What we read
Checked September 1, 2026.
- 1 Dose-Titration Effects of Fish Oil in Osteoarthritic Dogs
- 2 An un-commissioned randomized, placebo-controlled double-blind study to test the effect of deep sea fish oil as a pain reliever for dogs suffering from canine OA
- 3 Double-blinded Crossover Study with Marine Oil Supplementation Containing High-dose icosapentaenoic Acid for the Treatment of Canine Pruritic Skin Disease
- 4 The Supplementation of Docosahexaenoic Acid-Concentrated Fish Oil Enhances Cognitive Function in Puppies
- 5 USDA National Nutrient Database for Standard Reference, Release 28: Fats and Oils
- 6 Seafood Choices: Balancing Benefits and Risks
- 7 The production of fish meal and oil - 3. The process
- 8 Marine Oils
- 9 Fish oil
- 10 Potential Adverse Effects of Omega-3 Fatty Acids in Dogs and Cats
- 11 Toxic element levels in ingredients and commercial pet foods
- 12 Reading Labels
- 13 A randomized, double-blinded, placebo-controlled multicenter study on the efficacy of a diet with high levels of eicosapentaenoic acid and gamma-linolenic acid in the control of canine atopic dermatitis
- 14 Menhaden Fishing Industry (Historical Marker SC-214)
- 15 Menhaden in Virginia
- 16 Fish Oil Dosing in Pet Diets and Supplements
- 17 Evaluation of the effects of dietary supplementation with fish oil omega-3 fatty acids on weight bearing in dogs with osteoarthritis
- 18 Beneficial effects of chronic administration of dietary omega-3 polyunsaturated fatty acids in dogs with renal insufficiency
- 19 Long-chain (n-3) polyunsaturated fatty acids are more efficient than alpha-linolenic acid in improving electroretinogram responses of puppies exposed during gestation, lactation, and weaning