How To Feed Canned Mackerel To Dogs (Serving Size Guide)

Before we discuss dosage, you need to understand *why* we’re doing this. It’s not about a tasty treat; it’s a strategic nutritional intervention. When I analyze a food, I look for its ‘nutritional payload’—the concentration of high-value nutrients versus empty calories or fillers. Canned mackerel has an incredible payload.

The Omega-3 Powerhouse: EPA & DHA

The primary reason to add mackerel to your dog’s diet is its high concentration of Omega-3 fatty acids, specifically Eicosapentaenoic Acid (EPA) and Docosahexaenoic Acid (DHA). While some dog foods claim ‘Omega-3s’ from plant sources like flaxseed, dogs are notoriously inefficient at converting plant-based ALA into the usable EPA and DHA forms. Marine sources like mackerel provide it directly.

• Anti-Inflammatory Action: Chronic inflammation is the root cause of many canine health issues, from arthritis to skin allergies. EPA is a powerful natural anti-inflammatory that can help manage joint pain and reduce itchy skin.
• Cognitive Function: DHA is a critical component of brain and retinal tissue. For puppies, it’s vital for development. For senior dogs, supplementing with DHA can help support cognitive function and slow the progression of canine cognitive dysfunction.
• Skin and Coat Health: A dull, flaky coat is often one of the first signs of an essential fatty acid deficiency. The oils in mackerel help to nourish the skin from the inside out, leading to a glossier, healthier coat and reduced shedding.

More Than Just Fish Oil

While the Omega-3s are the star of the show, mackerel is not a one-trick pony. It provides a host of other essential nutrients:

• High-Quality Protein: Mackerel is a complete protein, containing all the essential amino acids your dog needs to build and maintain lean muscle mass.
• Vitamin D: This is a critical nutrient that many dogs, especially those on homemade diets, can be deficient in. Vitamin D is essential for regulating calcium and phosphorus levels, crucial for bone health.
• Vitamin B12 (Cobalamin): Vital for a healthy nervous system, brain function, and the formation of blood cells.

Adding a small amount of mackerel isn’t just ‘humanizing’ your pet. It’s a calculated move to fill the nutritional gaps present in many mass-produced commercial dog foods. You’re providing bioavailable nutrients that their body can use immediately for critical functions.

Not all canned mackerel is created equal. The wrong choice can negate the health benefits and even cause harm. The grocery store aisle is a minefield of high-sodium, high-fat, and inappropriately seasoned products. You must learn to read the label like a forensic scientist. Here is your non-negotiable checklist before a can ever goes into your cart.

The Non-Negotiable Rules of Engagement:

• Rule #1: Packed in WATER Only. You will see mackerel packed in soybean oil, olive oil, or other vegetable oils. Avoid them all. These add a significant number of unnecessary calories and, depending on the oil, can even be pro-inflammatory, defeating the purpose of the Omega-3s. We want the fish, not the cheap filler oil. The only acceptable ingredient is mackerel in water.
• Rule #2: ‘NO SALT ADDED’ is Mandatory. This is the single most important factor. A dog’s daily sodium requirement is very low. A single serving of mackerel packed in brine can contain several hundred milligrams of sodium, far exceeding their daily needs and putting a strain on their heart and kidneys. The label must explicitly state ‘No Salt Added’. Do not trust ‘Reduced Sodium’ claims.
• Rule #3: Scrutinize the Ingredients List. Avoid any product with added broths, spices, flavorings, or sauces. Ingredients like onion powder or garlic powder, often found in ‘tomato sauce’ or ‘mustard sauce’ varieties, are toxic to dogs. The ingredient list should be brutally simple: ‘Mackerel, Water’. That’s it.
• Rule #4: Assess the Bones. Most canned mackerel is ‘skinless and boneless,’ which is the safest option. However, some brands leave the tiny, pressure-cooked bones in. These are typically soft enough to be mashed with a fork and are an excellent source of calcium. If you can easily crush them into a paste, they are safe. If you find any bones that feel hard or sharp, discard them.

Hacker Tip: Ignore the flashy marketing on the front of the can. The ‘high in protein’ or ‘wild caught’ claims mean nothing if the product is swimming in salt and oil. The truth is always on the back, in the fine print of the nutrition facts panel and the ingredients list. That is your battlefield. Master it.

This is where precision is paramount. We are not ‘eyeballing’ a portion. We are administering a specific, supplemental dose to achieve a nutritional benefit without overloading the system with calories or fat. Overfeeding can lead to digestive upset or, in sensitive dogs, contribute to pancreatitis. Always introduce any new food slowly and consult with your veterinarian, especially if your dog has a pre-existing health condition.

The following guide is a starting point for a healthy adult dog. The total amount should be split into 2-3 feedings throughout the week, not given all at once. This ensures a steadier supply of Omega-3s and is easier on their digestive system.

A ‘standard can’ is typically around 3.75 to 4.25 ounces (approx. 120g). When you open a can, drain the water thoroughly. Flake the appropriate amount with a fork and mix it directly into your dog’s regular food. You can refrigerate the remaining mackerel in a sealed, airtight container for up to 3 days. Do not leave an open metal can in the refrigerator.

A smart hacker always assesses the risks. While mackerel is safer than many other fish, you must be aware of the potential downsides and how to mitigate them. Ignoring these can lead to serious health consequences for your dog.

Mercury Contamination

Mercury bioaccumulates up the food chain. Large, predatory fish like shark, swordfish, and certain species of tuna have the highest levels. Mackerel is a smaller, shorter-lived fish, placing it much lower on the food chain and therefore lower in mercury. By sticking to the recommended serving sizes, the risk of mercury toxicity is extremely low and is far outweighed by the anti-inflammatory benefits of the Omega-3s.

Allergic Reactions

Just like humans, dogs can be allergic to fish. When you first introduce mackerel, give only a tiny amount—less than a quarter of the recommended first serving. Over the next 24-48 hours, monitor for any signs of an adverse reaction, which can include:

• Excessive scratching or licking
• Red, inflamed skin or hot spots
• Vomiting or diarrhea
• Ear infections

If you notice any of these signs, discontinue feeding mackerel and consult your vet. Do not introduce any other new foods at the same time, or you won’t know what caused the reaction.

Pancreatitis and High-Fat Foods

Mackerel is an oily fish. This high-fat content is what provides the beneficial Omega-3s, but it can also be a trigger for dogs prone to pancreatitis—a painful and potentially fatal inflammation of the pancreas. If your dog has a history of pancreatitis or is a breed susceptible to it (like Miniature Schnauzers or Yorkshire Terriers), you must speak with your veterinarian before adding any extra fat to their diet. This is non-negotiable. For healthy dogs, the risk is low when sticking to the correct serving sizes and using only mackerel packed in water, not oil.