Yellowstone National Park offers some of the worlds finest inland trout fishing. The variety of water and the number of large fish are astounding. Fishermen from all over the world frequent Yellowstone National Park's magic waters.

You can download the full Yellowstone fishing rules and guidlines here(pdf):

Yellowstone Fishing Rules and Guidelines

Lead tackle of any kind is banned from Yellowstone. Yellowstone National Park requires a fishing permit to fish park waters. You can buy them from all visitor centers, ranger stations and general stores. For those 16 years or older, the fees are $15 for a three day permit, $20 for a seven day permit, and $35 for an annual permit. Children under 15 need a free signed permit if they are not under the direct supervision of an adult. Yellowstone National Park also has a barbless-only policy on park waters to uphold the quality of the fishery. Daily fishing is from 5 AM until 10 PM. Check the guidelines for specific season dates as they vary by body of water. Only artificial baits are allowed in Yellowstone National Park and all native fish are catch and release (cutthroat, grayling, whitefish). You do not need a Wyoming or Montana license to fish Yellowstone National Park, only the required park permit.

A fishing trip to Yellowstone National Park is something you will remember forever. If it is quality inland trout you are after along with fantastic scenery, there is no finer place.

Yellowstone Lake: This lake is the largest body of water in Yellowstone National Park , and the second largest freshwater high altitude lake in the world at 136 sq. miles. The fishing in Yellowstone Lake consists of lake trout and cuttroat trout. Any lake trout caught must be killed. The cutthroat can be caught along the shoreline using single hook barbless spinners, or using dry flies in low light hours. Streamers will take cutts in 3-8 feet of water as well.

Slough Creek: This world famous creek offers a unique fishing experience. Cutthroat, cuttbows and rainbows grow to great size here. The fish around Slough Creek campground can be incredibly picky. Keep a diverse selection of realistic patterns so you can effectively match the hatch. There are three main meadows upstream from the campground, with the first meadow having more wary fish due to more pressure. Naturally, the third meadow (11 miles uptrail) has the least picky fish.
Rusty Spinners, small blue wing olives and good sized green drakes are some of the patterns that work on this tricky river.

Lamar River: This scenic river flows through the heart of the famous Lamar Valley. You will be fishing amongst a true picture of the last real west. Casting the bends and pools while hundreds of bison, antelope, elk and eagles fly overhead is a unique experience. The Lamar is a good attractor pattern fishery. Hoppers, spiders, ants, beetles and vairous terrestrials are good choices.

Yellowstone River: Fishing in the Yellowstone inside the park is not as good as it once was due to a huge decline in the cutthroat population of Yellowstone Lake ( lake trout predation). You can spend all day and have one fish, although that fish will probably be of size. Standard attractors and streamers fished patiently will land a nice cutt.

Firehole River: This is a great stream for brown, rainbow and brook trout. Fishing the Firehole can be a unique experience due to it's proximity with many geothermal features in Yellowstone National Park.. Terrestrials work well, along with pale morning duns, blue winged olives and streamers of various sizes.