Streamers typically represent minnows and are definitely the best way to target the biggest fish in any river or lake. Stripping these patterns through deeper runs and holes will often lure leviathans from the depths; heavier tippets and stronger fly rods are a must.
TIP: Don't use anything lighter 4X tippet with the smaller patterns; nothing lighter than 3X with the larger patterns. For more action, use a non-slip loop knot to tie on your streamer.