The pellicle is a shiny, tacky thin skin or film of protein that forms while drying fish.
When smoking fish it is often brined or cured. The next step is to dry the fish and let the pellicle form.
The pellicle is important for several reasons… it helps seal in the moisture, it keeps the fats in the fish from rising and spoiling the fish, it keeps contaminants out of the fish, and it provides a surface for your smoke to adhere to.
To dry your fish place it skin side down on a rack or pan in a cool, dry, breezy place. A fan, set on low, can be used to help the drying process. It usually takes from 1-3 hours for a good pellicle to form.
Letting the pellicle form is an important step in smoking fish. Skip it and your smoked fish will be dry.