There is not good fishing from the shore of Flathead Lake. You can charter a boat from Bigfork Harbour to get out where the fishing is good. A-Able Fishing is very reputable.
Sorry, at this late hour I cannot recall the names of the fish (I'm not a fisherman) but some years ago the "wisdom" of the biologists messed with the natural balance of the lake so the fish population is quite different from the natural state. The fishing folk around the Lake will be able to fill you in on the details.
For more local fishing conditions, contact either the Sportsman Ski Haus or Snappy Sport Center in Kalispell. Both of these are huge, locally-owned sporting goods stores where you can obtain fishing licenses and the latest info about what fish are being caught where, and with what bait.