Why Fish Is Dangerous To Cats by Jean Hofve, DVM. "Fish may not be safe to feed to cats. Predatory fish at the top of the food chain, such as tuna and salmon, may contain very elevated levels of heavy metals (including mercury) as well as PCBs, pesticides, and other toxins. Tilefish (listed on pet food labels as "ocean whitefish") are among the worst contaminated, along with king mackerel, shark, and swordfish. These fish are so toxic that the FDA advises that women of child-bearing age and children should avoid them entirely'; and they recommend only 1 serving of albacore tuna per week due to its high mercury levels. If these fish are dangerous to children, cats are at even more risk!"
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