The Truth About Fish for Cats
Tuna, salmon, mackerel: fish is the **“stereotypical” food** for cats.
In reality, **the truth is more nuanced**:
- Some fish are **excellent**.
- Others are **dangerous** (see article on tuna).
- All require **proper preparation**.
Let’s see the 5 fish that are truly beneficial for cats.
Why Fish is Good
Nutritional Benefits
High-quality proteins:
- Complete amino acid profile.
- Easy to digest.
Omega-3 (EPA, DHA):
- Anti-inflammatory.
- Good for fur, joints, heart.
Vitamins:
- D (calcium).
- B12 (energy).
- E (antioxidant).
Minerals:
- Iodine (thyroid).
- Selenium.
- Zinc.
Most "Beneficial" Fish for Cats
In order of benefits:
1. Salmon (wild):
- High in Omega-3.
- Low mercury.
- Vitamin D.
2. Sardines:
- High in Omega-3.
- Very low mercury (small fish).
- Calcium (edible with bones).
3. Mackerel (small):
- High in Omega-3.
- Intense flavor.
4. Cod:
- Lean, light.
- Suitable for delicate cats.
5. Trout:
- Omega-3.
- Low allergenicity.
The Top 5 Fish
1. Salmon
Pros:
- Abundant Omega-3.
- Loved flavor.
- Versatile.
Cons:
- Medium-high cost.
- Wild is better than farmed.
Preparation:
- Boiled or steamed.
- Never raw (parasites).
- Without salt, oil, seasonings.
Quantity:
- 30-50 g for medium cat.
- 1-2 times a week.
Storage:
- 2-3 days in the fridge.
- 1-2 months in the freezer.
Smoked Salmon:
- NO: too much salt, preservatives.
2. Sardines
Pros:
- Small fish: very low mercury.
- Can be eaten with bones (calcium).
- Low cost.
- High in Omega-3.
Cons:
- Strong smell.
- Possible refusal from some cats.
Preparation:
- In water, without salt (specific canned fish for cats).
- Possible fresh boiled sardines.
Canned human sardines:
- In oil: too fatty.
- In brine: excessive salt.
- Only in natural water: occasional OK.
Quantity:
- 20-30 g.
- 1-2 times a week.
3. Mackerel
Pros:
- Extremely high Omega-3.
- Intense flavor.
- Small fish: less mercury.
Cons:
- Fatty fish (more calories).
- Strong smell.
Preparation:
- Boiled or steamed.
- Never raw.
Quantity:
- 20-30 g.
- 1 time a week.
4. Cod
Pros:
- Lean.
- Delicate flavor.
- Suitable for cats with digestive issues.
- Medium cost.
Cons:
- Less abundant Omega-3.
Preparation:
- Boiled or steamed.
Quantity:
- 50-80 g (leaner = more volume).
- 1-2 times a week.
5. Trout
Pros:
- Omega-3.
- Low allergenicity.
- Delicate flavor.
Cons:
- Medium cost.
- Farmed: less omega-3.
Preparation:
- Boiled.
- Without bones if possible.
Quantity:
- 40-60 g.
- 1-2 times a week.
Fish to Limit
Tuna
See dedicated article.
Summary:
- High mercury (top predator).
- Thiaminase if raw.
- Only occasional.
Swordfish
Same problems as tuna:
- Very high mercury.
- Predator.
- Avoid or only occasional.
Shark, Marlin
Very high mercury.
Avoid.
Aquarium Fish
Never give:
- Treated with medications.
- Not checked for consumption.
Fish to Absolutely Avoid
Raw Fish (Unchecked)
Risks:
- Parasites (Anisakis).
- Thiaminase (destroys B1).
- Bacteria (Salmonella, Listeria).
Exception:
- Sushi-grade sashimi checked: occasional.
- Risk of thiaminase remains.
Fish in Brine/Salty
Excess salt:
- Toxic in cumulative doses.
- Kidney overload.
Smoked Fish
Chemically flavored:
- Preservatives.
- Salt.
Strongly Aromatic Fish
Herring, anchovies in oil:
- Preservatives.
- Salt.
Proper Preparation
Step 1: Choose Fresh Fish
Purchase:
- Trusted fishmonger.
- “Fresh of the day”.
- Quality frozen if necessary.
Step 2: Clean
- Remove fins.
- Clean interior.
- Remove bones if necessary (important for cat).
Step 3: Cook
Boiling:
- Clean water, no salt.
- 10-15 minutes.
- Let it cool down.
Steaming:
- More “natural” alternative.
- Preserves more nutrients.
Step 4: Portion
- Divide into small pieces.
- Without dangerous bones.
- Store or freeze.
Step 5: Serve
- Room temperature.
- Mixed with regular food or alone.
Quantities
General Rule
Snacks/supplementation: 10-15% of daily calories.
Average cat (4 kg):
- 30-50 g of fish per meal.
- 1-3 times a week.
Never replace main meals with only fish (lack of complete nutrients).
For Cats with Special Needs
Senior cats:
- Fish easy to chew.
- Intense flavor (appetite).
Cats with arthritis:
- Fish rich in omega-3.
- Anti-inflammatory effect.
Cats in recovery:
- Fish to stimulate appetite.
Commercial "Cat Fish"
Wet Fish-based Food
Pros:
- Balanced.
- Safe.
- Easy.
Cons:
- See mercury (some).
Top brands:
- Almo Nature (various fish).
- Schesir tuna/salmon.
- Cosma.
Cost: €1.50-3 per can.
Fish Snacks
Brands:
- Cosma Naturals fish snacks.
- Almo Nature snacks.
Pros:
- Pure fish.
- Convenient.
Cost: €5-15 per package.
Sustainable Species
For those who care about the environment:
Sustainable fish:
- Sardines (small, abundant).
- Mackerel.
- Anchovies.
- Herring.
- MSC certified cod.
To limit (due to overfishing):
- Bluefin tuna.
- Swordfish.
- Wild Atlantic salmon.
Sustainable alternatives:
- Responsibly farmed salmon (ASC, organic).
Myths to Debunk
Myth 1: “Cats live on fish.” False: in nature, they mainly eat small mammals.
Myth 2: “Raw fish is better.” False: multiple dangers.
Myth 3: “All cats love fish.” False: some prefer meat.
Myth 4: “Human canned fish is fine.” Dangerous: salt, oils.
Myth 5: “More fish, more health.” False: balance is essential.
Signs of Fish Allergy
Some cats are allergic:
Symptoms:
- Itching.
- Vomiting after meals.
- Diarrhea.
- Inflamed skin.
Solution:
- Exclusion diet.
- “Novel protein” food (rabbit, duck).
Ideal Frequency
Fish in meals:
- 2-3 times a week max.
- Varying species.
- Never daily.
Rest of the time:
- Meat (chicken, beef, turkey).
- Balanced commercial food.
- Variety.
The Truth
Fish is **not “cat food”**, but is a **valuable component** of the feline diet.
Excellent fish:
- Salmon.
- Sardines.
- Mackerel.
- Cod.
- Trout.
Limited fish:
- Tuna (mercury).
- Large predatory fish.
Forbidden fish:
- Unchecked raw.
- Salty/smoked.
Frequency: 2-3 times a week, in small portions.
Benefit: omega-3, variety, palatability.
Your cat loves fish. Now you know **how to give it properly**, in a healthy, sustainable, safe way.
Boiled salmon instead of canned tuna. Fresh sardines instead of canned in oil. Variation instead of monotony.
His diet improves. His health improves. And he thanks you with extra years of life.
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