The Anchors...

Anchor flies are an important part of my Czech nymph set ups.  The waters I fish are fairly high gradient and fast flowing.  Heavy flies are needed to bring the system down to the fish.  Since no weight is applied to the leader it all has to be in the flies.  When I first started Czech nymphing I tied anchor flies emphasizing the weight aspect.  I used oversized tungsten beads and lots of lead tape or wire to create a very heavy fly.  I never had high hopes of catching fish on these monstrosities, I just tried to tie something heavy enough to bring the other flies (the ones I tied to actually catch fish) down to were the fish were.  Lo and behold,  I caught just as many fish on the anchors as the "fishing flies".  Today I am no longer surprised when I catch a trout on an anchor fly but I still wonder what the hell the fish was thinking...

Though not necessary, jig hooks help flies ride hook point up to minimize snags.  Slotted tungsten beads allow you to mount larger beads on your hooks.

Cased caddis patterns are great choices for anchor flies.  This one will get to the bottom in the strongest currents.

My favorite anchor fly of all.  A large (size 10 or 12) flashback pheasant tail with an oversized slotted faceted tungsten bead and lead underbody.