You can keep 6 rainbow trout from Lightening Creek but none of those can be cutthroat trout. That is from Memorial Day weekend to December 1. After December 1, there is a catch-and-release season. There is no limit on lake trout in the Lightening Creek system. You can also keep 6 kokanee. Typically, they are found in the creek during the fall and early winter when they run into tributaries to spawn.
Fishing success varies by time of year. In the summer, fish deeper pockets and back eddys. I use bait or roostertails for the best success. If you fly fish, match the hatch in the spring and summer. Winter fishing is the biggest challenge.