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Asian Fishing Cat is  a rare  feline species evolved to feed exclusively on fish (© Karen Povey)

For some reason many cat guardians suffer from misconception that feeding fish every day is the best thing you can do for your cat. Even worse many cat owners base nutrition of their feline companions exclusively on tinned tuna or mackerel as this is usually the cheapest option when it comes to fish.

As explained on the charts provided in this article eating large quantities of large blue fish is not a good idea neither for humans nor for cats.  Contrary to popular belief fish is not species appropriate diet for cats. With the exception of few rare species such as Asian Fishing Cat most of the cats  will not go nowhere near the large body of water.  Granted,   occasionally we may encounter adventurous domestic cat which has mastered the fishing skills but on the whole cats and water do not mix very well. 

There is similar myth about cats and milk or dairy products whilst in reality most cats are lactose intolerant.

Every now and then properly chosen fish can certainly  complement feline diet but in general fish does not contain all the nutrients cats require for optimum health and well being.  On many occasions I have seen the cats that developed addiction to canned tuna and will not eat anything else.  I also often see cats that develop addiction to dry food or dairy products  due to opioids find in grains and dairy.
Cats that develop addiction to these types of food  should undergo detox program and then be introduced to species appropriate diet. This should be discussed with your holistic veterinarian.

Tuna meat can provide protein  and omega 3 fatty acids but it will fail to deliver all the essential minerals, enzymes and micronutrients. Apart from this most of the large blue fish today is loaded with toxic mercury. In humans it may take years for cumulative effect of mercury poisoning to cause clinical symptoms. In small animals such as cats even one can of tuna per week may be too much.

Symptoms  of mercury poisoning in cats include:

  • Lack of coordination
  • Muscle weakness
  • Mental disturbance and memory loss
  • Vision impairment
  • Skin rash
  • Enteritis and diarrhoea

If you have been feeding your cat large amounts of tuna on a regular basis and he has any of the symptoms listed above, you should take him to a vet immediately.

Let us have a look at some informative charts about mercury prevalence in sea fish.








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