Why is there fish in my wine?

May contain fish

As dining requirements and allergies become more common you’ll be hearing more about a little thing called vegan wine. Many people are surprised to find out wine is typically not vegan, nor is it even vegetarian. Why? Because of Isinglass and its friends.

Haven’t heard of Isinglass? You’d know it better as fish bladder.

Firstly, yes. Winemakers do use fish bladder to make wine. To be more specific, Isinglass is used to clear the wine of any solids that may be floating around which could alter the feel, taste and smell of the wine.

Throughout the winemaking process grape skins and vine stems are mixed in with the juice. While a necessary component to help the wine's structure, flavour and texture they need to be removed along with dead yeast (if any). Any remaining sediment can cause faults in the wine during bottling which can be the difference between a premium and a flawed product.

When fining agents are added to the vats the wine's sediment (protein) is attracted to them and attaches to the fining agent. Eventually, the cluster of fining agent and sediment sinks to the bottom and leaves the rest of the wine clean and clear. The winemaker easily removes the clumps of protein before finalising the wine making process.


The list of fining agents is much larger than just fish bladder:

  • Blood and bone marrow
  • Casein (milk protein)
  • Chitin (fibre from crustacean shell)
  • Egg albumen
  • Fish oil
  • Gelatin
  • Seaweed
  • Bentonite (a form of clay)
  • Polyvinylpolypyrrolidone - google it


Before you renounce wine from your life, understand these agents are taken from the final product before bottling and trace amounts are so low often winemakers can’t even get a reading. Like everything nowadays, it is a matter of legal compliance which causes the label on your wine to say ‘may contain traces of fish’.