Join Date: Dec 2014
Location: Northern California
I think no loop is clearly the default for trout. I've never head of anyone recommending anything else. On the other hand, depending on the fish, the conditions, and which part of the swing you are in giving the fly some motion, not necessarily only stripping, just twitching, is a great tactic for trout on the swing. Try everything until you find something that is working. Id say having no loop, with line often in your upper hand and giving the gentlest of strip sets when you feel a strike is near the center of the bell curve covering the "default" territory for trout swinging. It's great fun!
Steelhead have been conditioned to grab seagoing prey like squid that are good swimers. So the take are sometimes complicated by very high velocities. There may be some flies where trout might do that kind of take, but if you are using a nymph imitation most trout will often take it very casually and a loop would be terrible. I was fishing at the Fall River in CA a few days ago and that would be the extreme example where we were swinging very small nymphs in spring water on 20' leaders and the fish would slowly come up after them from as much as 10 or 15 feet away. They sucked them up so easy that the grabs of 20" fish usually felt like the fly was pulling over an underwater plant or something - at least until they felt the hook. If you had a loop in that case you would probably never catch anything and never even know you had take in a lot of cases.