Montana Fly Fishing 3 min read

DIY Guide to Fly Fishing the Tongue River in Montana

Ken Sperry

Posted by Ken Sperry

February 27, 2024

Tongue River flowing through south east Montana.

The Tongue River, originating from the majestic Bighorn Mountains in Wyoming and extending toward Montana, is a hidden gem often overlooked by fly anglers. This waterway meanders towards the east and north, ultimately joining the Yellowstone River at Miles City in Montana. Although it may not be a well-known fly fishing destination, the Tongue River offers a unique experience for those who seek to venture off the beaten path.

Below, you will learn more about the river, the fish it contains, and the important information you need to complete your trip.

About Tongue River

Floating the Tongue River from Tongue River Reservoir to the Yellowstone River in Montana.

What Is Tongue River Like?

A backdrop of mountains, prairies, and trees helps to make this a great location for fly fishermen. Since it’s so close to the Tongue River Reservoir State Park, which has camping, you can bring the entire family.

Much of the river’s course crosses the various landscapes of eastern Montana. It goes through the Tongue River Canyon, the pine hills, buttes, and grasslands.

Type of Fish in the Tongue River

Below the dam, there are scattered rainbow and brown trout, some of them quite hefty. However, the river from the dam to Miles City is generally known for species like channel catfish, sauger, smallmouth bass, carp, and walleye.

Tongue River Trout Fishing Map

Map of access points and the best places to fish on the Tongue River below Tongue River Reservoir in Montana.

Get Directions to the Fishing Access Points shown above with the DIY Fly Fishing Map

Best Places to Fish the Tongue River

If you’re into trout fishing, the best fishing spots are located in the first 10 miles from the dam, where the river narrows into a canyon. Access is available below the Tongue River Reservoir dam.

The river depth increases in this area, which helps to keep the water temperatures down, and the water flow scours the bottom gravel, making the area suitable for smallmouth bass and trout.

Floating is a great way to experience the canyon, but you should be prepared to organize your own shuttle.

Typically, when choosing their fishing spots, anglers will want to consider the season, the water level, and the amount of competition in the area—since it can get busy.

Best Time to Fish the Tongue River

Fishing starts on the third Saturday in May and runs through November 5 here, although ice fishing is allowed at the reservoir. 

The optimal time to visit is during the spring and early fall.

In the summer, the lower river can experience significant dewatering due to irrigation and drought. In the worst cases, the river can practically dry up. However, if you plan your visit carefully, you can still enjoy excellent fishing for smallmouth bass and pike downstream of the canyon stretch.

Stream Flow and Current Conditions

Check the stream conditions before heading out to fish the Tongue River. The USGS stream gauge below Tongue River Reservoir near Decker, MT, provides a good indication of current conditions.

The graph below shows the stream flow (discharge) for the past 7 days. If flows are considerably above or below historical norms (yellow triangles on the chart), then fishing conditions may not be ideal.

Tongue River at Tongue R Dam nr Decker MT

  • Streamflow: 84.6 ft³/s
  • Gage height: 10.37 ft
Streamflow GraphGage height Graph

Best Flies for Tongue River

Whether in northern Wyoming or southern Montana, you will find that the flies you use for fishing Tongue River tend to be the same.

Some of the most popular and successful options for anglers include Pheasant Tail nymphs and Wooly Buggers. Other good choices include midges, PMD, caddis, and beatis.

During the latter part of summer, hopper imitations can do well. This is when there are a lot of actual grasshoppers in the area, which the fish tend to like.

Here is a list of general fly pattern recommendations for the Tongue River:

Dry Flies

  • Yellow Sally (#12 – 16)
  • Yellow Humpy (#10 – 18)
  • Parachute Sulphur (#14 – 18)
  • Parachute Adams (#12 – 22)
  • Light Cahill (#10 – 18)
  • Elk Hair Caddis (#8 – 16)
  • Yellows Stimulator (#8 – 14)
  • Chernobyl Ant (#8 – 12)
  • Griffith’s Gnat (#16 – 24)


  • Pheasant Tail (#12 – 20)
  • BH Hare’s Ear (#12 – 20)
  • Rainbow Warrior (#14 – 22)
  • Pat’s Rubber Legs (#4 – 12)
  • Golden Stonefly (#6 – 10)
  • Tellico Nymph (#12 – 18)
  • Zebra Midge (#16 – 22)
  • WD40 (#16-20)
  • Y2K Egg (#12 – 16)


  • BH Wooly Bugger (#2 – 6)
  • Sculpzilla (#4)

Gear Recommendations

A 9-foot 5-wt fly rod and matching fly reel with a floating line is perfect for fishing for trout. A tapered 9-foot leader, with tippet size 3X to 5X to match the flies you are throwing, is pretty standard.

Tongue River Fishing Report

Currently, there are no area fly shops, guides, or websites that regularly provide a fly fishing report for the Tongue River in Montana.

Fishing Regulations

The state of Montana requires that all people 12 years of age and older have a valid fishing license. There are resident and non-resident sport fishing licenses available.

You can purchase a Montana state fishing license and learn about the most current regulations through the Montana Fish, Wildlife & Parks.

Trip Planning Tips

You may find that staying at Tongue River Reservoir State Park is a good option. You can easily access the river from here.

The park features a campground with 81 sites that can be reserved with electric hookups. 27 of the sites are double occupancy with two electrical hookups. The park also has 80 non-reservable non-electric sites.

Other facilities at the campground include a dump station, toilets, boat ramps, and a fish cleaning station. There is a beach area for swimming and picnicking, as well.

Decker, Montana is the closest town to the dam and this part of the river. Many anglers will choose to camp in the area rather than choosing to lodge in town, but it’s up to you.

Looking for more places to fish? Check out our DIY Guide to the Best Fly Fishing in Montana