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Onon River

Want to target the world’s largest salmonids?

The Onon River is a wild, weaving, and wondrous river. We’ve fished the Buryat and middle sections of the river and have been blow away! Some of our biggest ever taimen have come out of the Onon River, but we’ve also spent considerable time looking for amur trout, lenok, grayling, and amur pike. There’s never a dull moment on the Onon River and, in a day, you could be fishing with anything from a 10-weight to a 4-weight and alternating between heavy streamers, nymphs and dry flies.

Drift-boat fishing for taimen is a spectacular experience, and Mongolia River Outfitters are among the premier guides and taimen conservation vanguards specializing in this type of fishing. They offer fishing licenses and travel packages to the far-flung and desolate Buryat region with a week’s worth of drift-boat fishing, where a new stretch of river, embedded into the most pristine and grand wilderness surroundings imaginable, is explored each day for seven days.

US outfitter, Mongolia River Outfitters, has fly-fished in Mongolia for over three decades. They offer outstanding services, wonderful fishing, and conservation leadership. Their adventures are promoted and trusted by the world’s most respected fly-fishing agencies.


Most anglers arrive seeking taimen, but quickly realize that Mongolia also boasts exceptional fly fishing for trout, pike, and grayling. 

Taimen (Hucho taimen)
Taimen are the biggest and baddest of all trout species. They are top-tier predators. They own the river. These fish attack ducklings, mice, and even gophers swimming in the river.  Taimen are often seen plowing across the surface charging trout. A big fish will drive a freaked out trout onto the bank. Then the taimen – jaws snapping – will wildly follow the trout up onto shore trying to eat it. This Onon River, quite likely, has Mongolia’s strongest taimen population. And the fish grow to more than 150cm!

Amur Trout (Brachymystax savinovi)
This trout species is unique to the Amur system and found nowhere else on the planet. Amur trout are beautiful with coppery flanks, big black spots and heavy shoulders. They hit the fly with commitment and fight hard.  Up to 30 inches.

Lenok (Brachymystax lenok)
Lenok are found throughout Mongolia. They are a wonderful and ancient trout with silvery bodies, bright red bands, and black spots. Most fly caught Mongolian trout come in between 14 – 20 inches, but fish well over 20 inches are landed each season.

Amur Pike (Esox reichetti)
Amur Pike are a native species found in only two places… In the Amur-drainage and the Sakhalin island. Amur pike are ornery. Pike tend to haunt backwaters and soft pockets along the river.  Amur pike hammer flies and grow to well over 40 inches.

Grayling (Thymallus)
Mongolia has four species of grayling. The Amur grayling found in this river are typically small (less than 10 inches). They’re found in pockets of fast water with schools actively feeding on tiny hatches. If you specifically want large grayling, the Fish Mongolia operation is your spot. 

Asp (Pseudaspius leptocephalus) 
Asp are sometimes called freshwater tarpon due to their bright silver bodies. Asp typically hang out in back eddies where they feed on smaller fish. They are fun to catch and beautiful to see. Asp have thick bodies and often measure between 18 – 25 inches.

The Gear

For taimen, you’ll want to bring a 9′ 10-weight paired with a solidly-braking fly reel spooled with a floating line. Also bring along a sinking line in case you’ll need to dig deeper for the fish. For lenok and grayling a 9′ 5 or 6-weight will do the trick. As for flies, you’ll need 15 – 30 centimeter baitfish imitations, a few surface flies that imitate mice, as well as some miscellaneous nymphs, dry flies and streamers. 

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