Originally Posted by dshort
They'll take the same flies that a wild trout will take after they've been in the stream for a week or so and all of the worm dunkers and truck chasers will be off to the next stream so you can pretty much have it to yourself. Wooley buggers, hare's ears and pheasant tail nymphs are all good bets.
Agree with Dshort. I've been involved in stocking Browns and Rainbows over the past couple of years up here in the Pocono freestone streams and I've seen both varieties take up what I'd consider to be natural feeding lines and start feeding actively within 20 minutes of being stocked. In my experience, they will strike on almost anything that a wild trout will strike on; including some of the classic dries, nymphs and streamers that have aleady been mentioned by the other posters.
As already recomended, I find that wooly buggers do work well for Rainbows; in black/black, olive/black, brown/brown and cream. Another good fly this time of year for Rainbows is a Chernobyl Ant; size 10 or 12, particlarly after a good rain or if the water is off-color.
Some of my friends have been know to "cheat" a little with freshly stocked Browns and Rainbows by tying up something that looks like a trout pellet; size 14-16, in brown. They do work well on freshly stocked fish. But, I've never gotten the urge to use one; and I hope I never do!