Fish oil

Fish oil, EPA and DHA explained, with dog arthritis research, limits of the evidence and questions to ask before choosing a supplement.

Ingredient Directory›Fish oil

Ingredient & nutrient profile

Fish oil

A source of marine omega-3 fatty acids. Look beyond the words “fish oil” to the amounts of EPA and DHA and the evidence for the intended use.

Fat and OilDogCat
Ω3
Fish oilNutritional role • Research • Practical context
SpeciesDogs and cats
ScopeIngredient and nutrient context
AssessmentInitial evidence summary
Sources checked23 September 2026
Nutritional role

What it contributes

Fish oil is a mixture of fats, rather than a single active substance. EPA and DHA are the long-chain omega-3 fatty acids commonly discussed in clinical nutrition. The amount of oil in a capsule or food does not, by itself, tell you how much of either fatty acid it supplies.

Species and formulation

Read it in context

This profile is relevant to both dogs and cats, but the linked arthritis trial tested dogs only. Its findings should not be presented as evidence that the same product or dose treats arthritis in cats. Tufts clinical guidance also discusses fish oil in selected heart patients, with veterinary oversight. [2]

Research

What the evidence shows

Roush and colleagues conducted a randomised, double-blinded trial involving 38 dogs with osteoarthritis. Dogs received a fish-oil-enriched food or a control food for 90 days; the enriched-food group had improved weight bearing. This supports the tested dietary approach, not every fish-oil supplement or every joint-health claim. Our study entry now includes a full-text appraisal, with participant flow, direct comparisons and funding checked. [1]

Limits and safety

Before changing the diet

Discuss supplementation with your vet, particularly if your pet has a bleeding disorder or already eats a diet high in omega-3 fatty acids. Product concentration and quality vary. More oil is not automatically more beneficial, and a study of a formulated food does not provide a universal supplement dose. [2]

Food labels

Questions worth asking

Ask for EPA and DHA amounts per daily serving, the source of the oil, storage instructions and quality-control information. Count what the existing food supplies before considering an additional supplement.

Connected evidence

Explore the study

Study links follow your species selection. A shared nutrient profile may discuss more than one species.

Dogs • Controlled trial • Full-text appraisalFish-oil-enriched food and weight bearing in dogs with arthritisRead the study summary, methods and limitations.
Sources

References and review scope

  1. Roush et al. (2010), original study
  2. Tufts University: heart disease and nutrition, fish-oil guidance

This is an initial, source-linked overview, not a systematic review or a product endorsement. FEDIAF is the European pet-food industry federation; its guidelines provide formulation context rather than an independent clinical trial. Study-specific access limitations are stated above.

Fish oil or fish protein hydrolysate?

These are different ingredients. Fish oil is the fat fraction; a protein hydrolysate contains protein-derived fragments. Read the fish protein hydrolysate profile for preparation differences and the limits of the canine behaviour evidence.

Research on this ingredient

We have not completed a research review for this ingredient. This does not indicate that it is ineffective or unsafe.

Products listing or mentioning this ingredient

88 products linked through reviewed ingredient occurrences from manufacturer declarations or partial editorial summaries. Whole-label verification may remain pending. An ingredient’s presence alone does not establish a nutritional outcome.

  • Burgess Adult Dog Light Chicken 12.5kg Burgess Adult Dog Light Chicken 12.5kg - Supadog Light in Fat Chicken Flavoured; United Kingdom; manufacturer declaration Dog; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • CXD-M Adult Medium breed CXD-M Adult Medium breed - CXD-M Adult Medium breed; United Kingdom; manufacturer declaration Dog; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • Gelert Pet Nutrition Maintenance White Fish & Rice Gelert Pet Nutrition Maintenance White Fish & Rice - Maintenance White Fish & Rice; UK; manufacturer declaration Dog; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • Hikari Gold Koi Food Hikari Gold Koi Food, editorial ingredient summary 2026-09-24; United States; partial summary Fish, Goldfish, Koi; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • Hikari Oranda Gold Hikari Oranda Gold, editorial ingredient summary 2026-09-24; United States; partial summary Fish, Goldfish; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • Hikari Sinking Goldfish Excel Hikari Sinking Goldfish Excel, editorial ingredient summary 2026-09-24; United States; partial summary Fish, Goldfish, Koi; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • Hikari Staple Koi Food Hikari Staple Koi Food, editorial ingredient summary 2026-09-24; United States; partial summary Fish, Koi; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • Hill’s Science Plan Healthy Mobility Medium Adult Chicken Hill’s Science Plan Healthy Mobility Medium Adult Chicken, editorial ingredient summary 2026-09-24; UK; partial summary Dog; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • Hill’s Science Plan Large Breed Puppy Chicken Hill’s Science Plan Large Breed Puppy Chicken, editorial ingredient summary 2026-09-24; UK; partial summary Dog; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • Hill’s Science Plan Medium Puppy Chicken Hill’s Science Plan Medium Puppy Chicken, editorial ingredient summary 2026-09-24; UK; partial summary Dog; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • James Wellbeloved Adult Chicken & Rice Dry Cat Food James Wellbeloved Adult Chicken & Rice Dry Cat Food, editorial ingredient summary 2026-09-24; UK; partial summary Cat; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • James Wellbeloved Adult Chicken & Rice Dry Dog Food James Wellbeloved Adult Chicken & Rice Dry Dog Food - James Wellbeloved Adult Chicken & Rice Dry Dog Food; United Kingdom; manufacturer declaration Dog; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • James Wellbeloved Adult Fish & Rice Dry Cat Food James Wellbeloved Adult Fish & Rice Dry Cat Food, editorial ingredient summary 2026-09-24; UK; partial summary Cat; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • James Wellbeloved Adult Fish & Rice Dry Dog Food James Wellbeloved Adult Fish & Rice Dry Dog Food, editorial ingredient summary 2026-09-24; UK; partial summary Dog; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • James Wellbeloved Adult Lamb & Rice Dry Dog Food James Wellbeloved Adult Lamb & Rice Dry Dog Food, editorial ingredient summary 2026-09-24; UK; partial summary Dog; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • James Wellbeloved Adult Turkey & Rice Dry Cat Food James Wellbeloved Adult Turkey & Rice Dry Cat Food, editorial ingredient summary 2026-09-24; UK; partial summary Cat; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • James Wellbeloved Kitten Turkey & Rice Dry Cat Food James Wellbeloved Kitten Turkey & Rice Dry Cat Food, editorial ingredient summary 2026-09-24; UK; partial summary Cat; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • James Wellbeloved Natural Adult Complete Dry Dog Food Duck & Rice James Wellbeloved Natural Adult Complete Dry Dog Food Duck & Rice - James Wellbeloved Natural Adult Complete Dry Dog Food Duck & Rice; United Kingdom; manufacturer declaration Dog; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • James Wellbeloved Puppy Lamb & Rice Dry Dog Food James Wellbeloved Puppy Lamb & Rice Dry Dog Food, editorial ingredient summary 2026-09-24; UK; partial summary Dog; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • James Wellbeloved Puppy Turkey & Rice Dry Dog Food James Wellbeloved Puppy Turkey & Rice Dry Dog Food, editorial ingredient summary 2026-09-24; UK; partial summary Dog; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • James Wellbeloved Senior Turkey & Rice Dry Cat Food James Wellbeloved Senior Turkey & Rice Dry Cat Food, editorial ingredient summary 2026-09-24; UK; partial summary Cat; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • Pero Foods High Meat - SBT Chicken Pero Foods High Meat - SBT Chicken - Pero Foods High Meat - SBT Chicken; United Kingdom; manufacturer declaration Dog; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • Purina Pro Plan Complete Essentials Adult 7+ Shredded Blend Chicken & Rice Formula Dry Dog Food Purina Pro Plan Complete Essentials Adult 7+ Shredded Blend Chicken & Rice Formula Dry Dog Food - Complete Essentials Adult 7+ Shredded Blend Chicken & Rice Formula Dry Dog Food; USA; manufacturer declaration Dog; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • Purina Pro Plan Large Athletic Everyday Nutrition Chicken Purina Pro Plan Large Athletic Everyday Nutrition Chicken, editorial ingredient summary 2026-09-24; UK; partial summary Dog; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • Purina Pro Plan Large Athletic Sensitive Skin Salmon Purina Pro Plan Large Athletic Sensitive Skin Salmon, editorial ingredient summary 2026-09-24; UK; partial summary Dog; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • Purina Pro Plan Large Robust Everyday Nutrition Chicken Purina Pro Plan Large Robust Everyday Nutrition Chicken, editorial ingredient summary 2026-09-24; UK; partial summary Dog; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • Purina Pro Plan Medium & Large Adult 7+ Sensitive Skin Salmon Purina Pro Plan Medium & Large Adult 7+ Sensitive Skin Salmon, editorial ingredient summary 2026-09-24; UK; partial summary Dog; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • Purina Pro Plan Medium Everyday Nutrition Chicken Purina Pro Plan Medium Everyday Nutrition Chicken, editorial ingredient summary 2026-09-24; UK; partial summary Dog; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • Purina Pro Plan Medium Puppy Sensitive Digestion Lamb Purina Pro Plan Medium Puppy Sensitive Digestion Lamb, editorial ingredient summary 2026-09-24; UK; partial summary Dog; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • Purina Pro Plan Medium Sensitive Digestion Lamb Purina Pro Plan Medium Sensitive Digestion Lamb, editorial ingredient summary 2026-09-24; UK; partial summary Dog; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • Purina Pro Plan Medium Sensitive Skin Salmon Purina Pro Plan Medium Sensitive Skin Salmon, editorial ingredient summary 2026-09-24; UK; partial summary Dog; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • Purina Pro Plan Small & Mini Everyday Nutrition Chicken Purina Pro Plan Small & Mini Everyday Nutrition Chicken, editorial ingredient summary 2026-09-24; UK; partial summary Dog; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • Purina Pro Plan Small & Mini Sensitive Skin Salmon Purina Pro Plan Small & Mini Sensitive Skin Salmon, editorial ingredient summary 2026-09-24; UK; partial summary Dog; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • Royal Canin Fit 32 Royal Canin Fit 32, editorial ingredient summary 2026-09-24; United Kingdom; partial summary Cat; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • Royal Canin Indoor 27 Royal Canin Indoor 27, editorial ingredient summary 2026-09-24; United Kingdom; partial summary Cat; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • Royal Canin Kitten Royal Canin Kitten, editorial ingredient summary 2026-09-24; United Kingdom; partial summary Cat; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • Royal Canin Maxi Adult Royal Canin Maxi Adult, editorial ingredient summary 2026-09-24; United Kingdom; partial summary Dog; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • Royal Canin Medium Adult Royal Canin Medium Adult, editorial ingredient summary 2026-09-24; United Kingdom; partial summary Dog; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • Royal Canin Medium Puppy Royal Canin Medium Puppy, editorial ingredient summary 2026-09-24; United Kingdom; partial summary Dog; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • Royal Canin Mini Adult Royal Canin Mini Adult, editorial ingredient summary 2026-09-24; United Kingdom; partial summary Dog; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • Royal Canin Mini Puppy Royal Canin Mini Puppy, editorial ingredient summary 2026-09-24; United Kingdom; partial summary Dog; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • Royal Canin Sterilised 37 Royal Canin Sterilised 37, editorial ingredient summary 2026-09-24; United Kingdom; partial summary Cat; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • ROYAL CANIN® Ageing 11+ ROYAL CANIN® Ageing 11+ - ROYAL CANIN® Ageing 11+; United Kingdom; manufacturer declaration Cat; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • ROYAL CANIN® Ageing 15+ ROYAL CANIN® Ageing 15+ - ROYAL CANIN® Ageing 15+; United Kingdom; manufacturer declaration Cat; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • ROYAL CANIN® Appetite Control Care ROYAL CANIN® Appetite Control Care - ROYAL CANIN® Appetite Control Care; United Kingdom; manufacturer declaration Cat; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • ROYAL CANIN® Beagle Adult ROYAL CANIN® Beagle Adult - ROYAL CANIN® Beagle Adult; United Kingdom; manufacturer declaration Dog; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • ROYAL CANIN® Boxer Adult ROYAL CANIN® Boxer Adult - ROYAL CANIN® Boxer Adult; United Kingdom; manufacturer declaration Dog; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • ROYAL CANIN® British Shorthair Adult ROYAL CANIN® British Shorthair Adult - ROYAL CANIN® British Shorthair Adult; United Kingdom; manufacturer declaration Cat; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • ROYAL CANIN® British Shorthair Kitten ROYAL CANIN® British Shorthair Kitten - ROYAL CANIN® British Shorthair Kitten; United Kingdom; manufacturer declaration Cat; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
  • ROYAL CANIN® Dental Care ROYAL CANIN® Dental Care - ROYAL CANIN® Dental Care; United Kingdom; manufacturer declaration Cat; Source data captured; Label verification pending; Evidence applicability requires the stated ingredient and study review scope
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