Dee Flies fish very well in the colder water of late fall through spring. They have what Alec Jackson calls the illusion of bulk, while not being bulky. And they can be tied on any good quality limerick bend 6x to 8x streamer hook in large sizes. The loop eye limerick streamer hooks tie a very nice Dee Fly.
Also, the Alec Jackson Blind Eye Spey Hook and the Partridge Blind Eye Barleet Hook tie very nice Dee Flies. Tie the blind eye hooks with 20 ro 25 pound test braided mono loop as the eye. Provided the mono loop is tied over 1/3rd or more of the hook, it will not pull off, and it provides for great fly action when you tie your tippet to the braided mono loop.
The Gold Riach is a good fly to use in the fall for steelhead here in the northwest when the river temps start to drop in mid to late October.
There are even double wing versions of most Dee Flies. These were and are tied when one does not have feathers of sufficient length to tie either the wing or the mobile body hackle.
Two of my favorite Dee Flies are the Akroyd and the Avon.