People may call it by different names, but this freshwater fish is universally considered a rush to catch. In the Korean language, it has over 10 different names in regional dialects, but most call it kueri (pronounced with a hard k/g sound). Biologists call it Opsariichthys uncirostris amurensis, with the last word denoting that it is native to the Amur River Basin. It is also native to Korea, Japan and China, the latter calling it the "horse mouth."

In English, it's referred to as the Korean piscivorous chub, with piscivorous meaning it is a fish eater. If that is too much of a tongue twister, just call it the "notch mouth." It is the kueri's unusually shaped mouth that distinguishes it from its own family species and other similar looking fish.

Its mouth has a notched upper jaw that fits neatly into a hooked lower jaw. It is this identifying characteristic that reveals its true nature, that it is a hunter of other fish. It is the only member of the docile, omnivorous carp family that has evolved into an aggressive predator.

When scouting out water to cast in, look for slight swirls and ripples. Kueri skim and dart right under the water's surface while hunting and a fast retrieve works best to attract its attention. You want to crank back the line as fast as you can without breaking the water and the spinning action of the lure. They are an extremely fast fish and sometimes they smack against the lure like a small shark making a test bump-and-run on its fleeing prey. If you're wearing polarized sunglasses you can easily see this action and watch them circle back to make a second or third strike when they take the lure.

Sometimes you catch a young one, only about 15 cm long, you wonder just how aggressive this fish is when it is biting a lure almost half its size. The fun begins when you locate a school that is actively feeding and then you can hook the larger adults that put a serious bend in your rod.

Their size length is similar to that of a rainbow trout but are lighter bodied and sleeker. An average sized kueri is usually between 20-30 cm, and a trophy fish would be measured at 40 cm. They have a brownish back and silvery white belly that flashes in the water.

The notch mouths will jump out of the water, snapping at insects, and flyfishing is one way to catch them. Use a rig similar to what you would use for brook trout and experiment with the flies. They are so gluttonous, that anything could work. Streamers and foam spiders are always the first to get cast out. With a spinning rod, use spinners and spoons of small to medium sizes, along with suspended minnow crankbaits.

Once ashore, you have to move fast if you want a photo of your catch. Kueri are notorious for flipping themselves off the hook as they pitch and twist once out of the water. Among Korean anglers, they aren't considered a quality eating fish and likewise, they have been given the nickname of a son-nim gogi, or a "guest fish," meaning that they aren't the primary fish to pursue of the resident species. Since they aren't valued for the dinner table, it could be the reason why their population levels are high and why it is almost impossible not to catch a few on a day's outing.

The notch mouths make their habitat in large bodies of water. They live in major Korean river systems and the larger lakes they flow into. Smaller lakes or reservoirs don't usually hold kueri unless a tributary is deep enough to provide access.

Copyright © James Card.