Flesh flies are usually fished when spawning salmon are dying and their decaying flesh is drifting downstream to hungry trout. On many rivers in Alaska, fishing flesh flies is the name of the game during certain parts of the season. Flesh flies are usually fished dead-drift like a nymph, but flesh flies often do quite well stripped out at the end of the drift like a regular streamer. Mandatory patterns for fly fishing Alaska and much of B.C.