Cats and Fish: Health Considerations

Many cats have an affinity for fish, and pet food manufacturers offer a wide range of fish-based products. While it may seem like a tasty treat for your feline friend, feeding your cat canned fish may not be as healthy as you think. Here are some important health considerations:

1. Mercury Concerns:
   A study conducted in 2016 at the University of Nevada, Reno examined mercury levels in over 100 pet foods, including those for cats and dogs. The results indicated that certain pet foods, particularly fish-based formulas, had mercury levels above the safety threshold established for small mammals. While 70 ng/g per day is considered safe, some pet foods contained up to 100 ng/g, raising concerns, especially for cats. The mercury concentrations varied widely among the tested brands, with salmon and trout-based pet foods showing the highest levels.
2. Toxins and Contaminants:
   Fish can harbor industrial toxins such as PCBs, dioxins, and pesticides. These toxins can accumulate in fish due to their consumption of contaminated plants and smaller prey. As larger fish eat these smaller fish, the toxins become more concentrated. This is a potential concern for both wild-caught and farmed fish.
3. Urinary and Kidney Issues:
   Fish used in canned pet foods usually consist of whole fish or by-products unsuitable for human consumption. These parts, including guts, feces, and bones, are high in phosphorus and magnesium, which can be problematic for cats, especially those with kidney or urinary tract issues. Sensitive cats might develop urinary problems, including cystitis and blockages, from consuming fish.
4. Hyperthyroidism:
   Fish and seafood are rich sources of iodine, which cats require in moderation. Some animal nutritionists suggest a link between the high prevalence of hyperthyroidism in cats and fish-based diets. Furthermore, polybrominated diphenyl ethers (PBDEs) found in some canned cat foods could contribute to this issue. PBDEs are flame retardants commonly found in various household materials and textiles.
5. Omega-3 and Omega-6:
   Cats need both Omega-3 and Omega-6 fatty acids for their health, which are considered essential and must be obtained from their diet. To ensure your cat gets these essential fatty acids, you can consider supplementing their diet with high-quality fish oil.

When choosing fish-based cat foods, it’s essential to be aware of potential risks. Salmon, tuna, and tilefish are the primary fish used in cat food, each with its own set of concerns:

• Salmon: Most salmon used in commercial cat food is farm-raised, not fresh-caught. Fish farms can be overcrowded and expose fish to pollutants, such as PCBs, pesticides, and antibiotics. They are also fed dyes to achieve the desired “salmon-colored” flesh.
• Tuna: Predatory fish like tuna can accumulate higher levels of heavy metals, including mercury, as well as PCBs and pesticides, due to their consumption of smaller fish. The FDA recommends limiting human consumption of albacore tuna due to these concerns. Tuna can also be highly addictive for cats, potentially causing them to refuse other foods.
• Tilefish (Ocean Whitefish): Tilefish, often labeled as Ocean Whitefish, are among the most contaminated fish. The FDA advises certain groups, like women of child-bearing age and young children, to avoid them entirely.

In summary, while fish can be a tasty occasional treat for your cat, it’s essential to use fish-based cat foods sparingly or consider alternatives to ensure your feline companion’s long-term health.