The Yale Book of Quotations cites as its source for this quote Graffiti: Two Thousand Years of Wall Writing, by Robert Reisner, 1971. But W.C. Fields’ granddaughter says he didn’t exactly say the last part of the quote: what he said was, “I don’t drink water. You know what fish do in it.” See her comment below.
Here’s another wonderful Fields quote (although don’t think in terms of present-day Afghanistan): “During one of our trips through Afghanistan, we lost our corkscrew. We had to live on food and water for several days.” (from the 1940 film, My Little Chickadee.)
See http://wcfields.com/ for a biography, filmography, and more about W.C. Fields.
writer gary garth mccann 
W.C. Fields, our grandfather, did not say exactly the last part of the fish quote attributed. He took care to be elegant, courteous and defender of the underdog. He did say, …you know what fish do in water.
Dr. Harriet A. Fields, granddaughter, http://www.wcfields.com
Thank you, Dr. Harriet A. Fields.
I would have thought, and have long assumed, that it was “fish sh*t in it”, but then I can be pretty sure I never actually heard that said in any Hollywood movie. I suspect I might have heard Johnny Carson say it on TV once upon a time, with attendant bleeping, and attribution to Mr. Fields.
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