Perdigon nymphs were for a few good year the secret flies for Spanish fishermen competitors. They had fantastic results with these flies. Now perdigon flies are not a secret anymore. At first look these flies are quite disappointing, very simple, overloaded with a big tungsten bead, slim body coated with resin. No dubbing, just a body thread and a strange black spot made of black marker in the wing case part. Everything has the logic here: slim body to let the fly sink fast, big bead to let the fly to go fast in the feeding area, black spot imitate the the torax and works like a hot spot. These flies are tied on small and very small hooks and are used only in fast flowing rivers.
I like more to play the nymphs, to move them in the feeding area to induce the strike of the fish. But sometimes seems that perdigon flies works fantastic. For this reason I tied a few models some time ago, aprox 4-5years. These flies had a special place in my fly tying box and sometimes make my day!

Bellow are a few nice spots where these flies works excellent! :

And one grayling and one trout on perdigon:

if you are looking to buy a few good and tested perdigon flies you should check here.