Isinglass is derived from the swim bladder (fin) of Sturgeon fish and has been used by home brewers and commercial brewers for ages with great success. Finings attract floating particles such as yeast cells. As the particles clump together and become heavy then drop to the bottom of the fermenter and settle better. They will allow you to bottle a brew quicker and clearer and promote less sediment to form in the bottle for a carbonated beverage and aid head retention in a beer. Supplied as a liquid this is ready to add directly to the brew. Add at least two days before bottling to aid clarity after 2 constant hydrometer readings taken a minimum of two days apart. Avoid stirring in if possible, remove airlock and pour in though hole. Put airlock back in and shake the fermenter to dispel any trapped CO2 gas.
Use 1 Litre bottle for 250 Litre Brew. If used at rate of 100ml per 25 Litre brew be aware as oxygen fills the bottle, as you remove product, it increase the risk of causing an infection to be passed into your brew. Keep refrigerated and use up as quickly as possible if being used like this to reduce chance of infections.