A Petling Biscuit is a type of food that can only be fed to a Petling. When fed to a petling, it will change that petling's color permanently to that of the color of the biscuit. For example, feeding an Aquamarine Petling Biscuit to a Brown pet will permanently change the color of the pet to Aquamarine. All petling biscuits cost playfish cash - some can be bought individually while others are only available in a bundle.