FAB Yellow Blob Barbless. Foam arsed Blobs are one of the commonly used flies on our Stillwater fisheries today. These can be used for the washing line technique. The blob fly is available in many colours and is an essential fly for all fly fishing anglers. If you are a Stillwater angler you should be carrying a selection of these in your fly box. Rainbow and Blue trout find the blob an irresistible pattern to swim past. International size for all competition fishing.