Our (two male) cats normally eat turkey and chicken flavoured canned wet cat food from our favorite cat food brand. However, we don't feed the cat's any other flavours which all contain fish, such as tuna or salmon, because of a vague recommendation from our vet:
"Don't feed fish-flavored cat food to cats, especially male cats. It's bad for them."
I attempted to find any evidence or statistics that any wet cat food causes any health problems of any kind in cats, specifically due to them having fish as an ingredient. Asking the manufacturer if the food has "safe" amounts of fish probably wouldn't be a trustable answer, either. Yet, this claim appears to be widespread and also very inconsistent:
I have heard foods that contain fish are bad for male cats. It can cause damage to their colon.
...male cats tend to have more UTI problems when fed a high amount of fish based foods. Its not really good to give fish food more then once a week.
Our vet warned us against feeding our cats too much fish-based wet food as we were dealing with Melon's second urinary-tract blockage.
Fish and beef are common food allergens in the cat and can cause inflammatory bowel disease and skin allergies in some cats. ... If you want to feed a fish-based food as a treat, please limit it to once or twice a week.
I've heard that fish contains a lot of ash that can cause UTI's.
In general, the small amounts of “fish meal” included as a flavoring and/or source of omega-3 fatty acids in cat foods are not a problem, but fish should not be a mainstay of any cat’s diet.
I would recommend avoiding fish flavored foods, which are said to be suspect in crystal formation.
At least one brand of cat food, and many others, use fish such as Tuna and Salmon as the main ingredient (not just a "flavour"). Given that this is true, the question is threefold:
- Can any amount of fish cause health problems in cats?
- If so, are there any observed amounts of fish that cause said health problems in cats?
- If so, how does this relate to the amount of fish in canned cat foods?