"Knack" wrote in message
ink.net...
I can get it locally for only US$1.00 per 15 ounce (425g) can. It has a
light tomtato gravy, but no vegetable oil. Like canned salmon, it includes
bones that are somehow softened by the heating-canning process. Contains
lots of protein, calcium, and fish oil.

..... and possibly ciguatoxin.

One of our vets was an emergency and critical care specialist for about 10
years. He was presented with several cases of severe diarrhea and vomiting
in cats that were recently fed mackerel. One case involved two of three
cats in a household - the third, asymptomatic cat, did not eat the mackeral.

At the time there was no test to definitively diagnose ciguatera poisoning,
however, the symptoms in the cats closely resembled ciguatera poisoning in
humans. He encountered a few other cats over the years with the same
symptoms who also recently consumed mackeral - that's why he suspected
ciguatera poisoning.

There's no way to detect ciguatoxin in fish -- and there's no way to destroy
it. Cooking, freezing and canning have no effect. So the best way to
reduce the risk is to avoid the fish that are known carriers of ciguatoxin.
Also, the larger the fish, the higher the concentration of ciguatoxin - big
fish eat little fish contaminated with ciguatoxin -- and bigger fish eat
those fish and so on. The highest risk is in fillets because they can be
cut from 100-pound King Mackerals.

I would avoid feeding raw fish to cats altogether. Some fish contain
thiaminase - which is an enzyme that destroys thiamin (vitamin B1). Cats
are very susceptible to thiamin deficiency because of their high requirement
for thiamin. The risk for thiamin destruction exists only when fish is fed
raw -- cooking destroys thiaminase.

Good luck.

Phil.




Just wondering about its magnesium content. Keep in mind that a jack
mackerel is only a 11" (28cm) fish that doesn't live for anywhere near as
long as a tuna.