Size 6 Heavy Jig Hook.
I needed a fly that had a perfect small baitfish profile, translucency, subtle flash, and colors that sinks really well without being heavy. After experimenting with and blending a lot of different materials, I found a blend of synthetics that fit the bill. This fly penetrates the water column extremely well because of its large tungsten head when you fish it with 2x or lighter tippet. Because the tail materials have some buoyancy, it actually balances almost perfectly horizontal under an indicator if you are into that sort of thing. Often the biggest challenge to catching big predatory trout is getting a decent fly in front of their face despite deep water, strong current, cutbanks, or structure that prevents most flies from being able to sink into the zone in time. benefit of this fly is that I have noticed that toothy fish can only spit it out with great difficulty, because the soft synthetic dubbing acts like velcro in their teeth. I usually fish it barbless because it is difficult enough to remove from a fish in the net without the aid of a barb.