I'm a pretty big Guinness fan, I must admit. You can't slam them, because each one is like drinking a sandwich, but a couple pints on a winter's night after steelheading...that's money. Guinness is one of the few breweries remaining that are so steeped in tradition, they kept using isinglass—"a gelatinous substance derived from the swim bladders of fish"—in the brewing process. Per this article on Deathandtaxesmag.com, the isinglass is used to help sediment settle quickly so it can be removed. Most other breweries stopped using it long ago. Guinness has been doing it the old way for 256 years and it's been working. But, even though you'd never detect a hint of fish in that pint, the vegans insist there must still be some microscopic fishy residue in the somewhere. So, thanks to some petition, Guinness is ditching the fish-gut derivative.