I feed a lot of fish to my exotic cats and as a breeder I encourage people to feed fresh fish! However, I read in an exotic cat chat room someone quoting page 338 of Feline Husbandry: "Diets containing large amounts of fish can cause vitamin deficiencies in cats. Many fish contain thiaminase in their tissues that destroys thiamin. Improperly processed foods containing fish have caused thiamin deficiency and even death in cats." Am I doing wrong? Should I stop feeding fish to my exotic cats?
Next week when I have time I am going to read a book on flying an F-16 fighter, and then I can write on a chat line and represent myself as a fighter pilot. I will quote sections out of the F-16 manual as if I understand them and lead people to believe that just by reading a book; I can fly an F-16.
Certain types of fish contain the enzyme thiaminase, especially raw carp of various species and raw salt water herring. Other fish that contain thiaminase include, flounder, mullet, most sharks, mullet, goldfish, whitefish, pike, cod, smelt, sprats, stints. A total of some 50 species most of which live in fresh water have been reported to contain Thiaminase. Wild animals apparently do not suffer thiamin deficiency in nature even though they eat a diet primarily of fish, because fish must undergo some putrefaction to release the enzyme. In vitro and in vivo experiments have shown that 1 kg of certain fish can destroy up to 25 mg thiamin. This degradation takes place within the first 30 min after ingestion, when still in the stomach.
One can easily see how inconclusive the statements in the Feline Husbandry text as sited on the exotic cat chat room can be. The statement "diets containing large amounts of fish can cause vitamin deficiencies in cats" is vague and useless to most exotic cat enthusiasts. What is the definition of large amounts? Is the term "large amounts" the same for a Fishing cat (F. viverrinus) as it is for Snow leopard (N. uncia)? Substances with an anti-thiamin activity are fairly common in nature and include structurally similar antagonists as well as structure-altering antagonists. Some of the preservatives in commercial food can also destroy thiamine, such as SO2. Also the pH level of certain commercial feed and supplements are detrimental to the thiamin that was included in the formulation. Heating above 100 degrees C kills all thiamine, but even mild heating in the presence of certain substances and with certain moisture levels kills most thiamin in commercially prepared "complete" diets. Processing, freezing, storage, and defrosting causes much of the vitamins present in fish and commercially available food to be destroyed or become unavailable to the animal. Only certain forms of vitamins that have been included in the food can survive these conditions, unfortunately most of the common and popular brands of commercially available diets for exotic/wild/nontraditional cats contain sources of vitamins that are readily degraded or made unavailable.
Vitamin E deficiency, also mentioned as being caused by feeding fish, is again a misleading statement. When cat diets contain excessive amounts of unsaturated fatty acids a vitamin E deficiency can occur. But again the questions are 1) what is an excessive amount? And 2) what fish provide these large amounts of unsaturated fatty acids? One should be careful in feeding exclusively canned red tuna, cod liver oil or colley (white fish), since these fish contain large amounts of unsaturated fatty acids. Commercial diets and dietary supplements often contain Vitamin E forms that a cat cannot use. Typically the diet tag or supplement label will say "Vitamin E supplement" and it will not list the proper form of vitamin E, which is alpha Tocopherol.
Anyone can use fish to feed their cats if certain guidelines are followed: 1) Do not feed fish that has undergone purification 2) Understand the natural diet of the cat you are feeding and try to mimic that as best as possible. In other words if its diet does not normally contain an exclusive fish diet then do not feed it exclusively fish. Occasional fish, or daily levels of fish in a properly balanced and fortified diet put together by a professional, is always your best advice. 3) Supplement the cats diet daily with Oasis, the only supplement in the world that has been formulated correctly for the wild feline/non traditional cat. 4) Do not feed a diet that is exclusively commercially derived. Most of the commercial diets for the exotic cats are similar to me reading the F 16 manual and calling myself a pilot. The "nutritionists" at these commercial facilities continually go against nature and what an exotic/ wild/ nontraditional cats needs. They continually dictate to the public that they "read the book" and they know how to fly despite the fact they never even saw an F-16, let alone ever sat behind the controls of one. Most commercial feeds for exotic/wild/nontraditional cats, unfortunately, have their expertise ON the bag, not IN the bag.