isinglass

thumb|Isinglass thumb|Swim bladder of a common rudd|rudd (Scardinius erythrophthalmus)

Isinglass ( ) is a form of collagen obtained from the dried swim bladders of fish. The English word origin is from the obsolete Dutch huizenblaas – huizen is a kind of sturgeon, and blaas is a bladder, or German Hausenblase, meaning essentially the same. The bladders, once removed from the fish, processed, and dried, are formed into various shapes for use.