Carp Biology

Carp can tolerate a wide range of temperatures and water conditions. They can survive in lakes that freeze in winter, as well as in rivers and sloughs that can warm to over 90 degrees Fahrenheit.

Carp can live almost anywhere, but wear your Wellies.

I’m including three types of carp in this series: common carp, mirror carp and grass carp. Common carp are by far the most, well, common species anglers encounter in American lakes and rivers. Mirror carp are a subspecies of common carp, so named because their scales are oblong and shiny, akin to small mirrors. While they are genetically slightly different from common carp, and vary dramatically in appearance, they generally share the same biology, habits and so forth. The techniques an angler uses to chase mirror carp are by and large the same as those used to catch common carp with flies. It’s the same game.

Grass carp, on the other hand, are strictly vegetarian, and thus provide a much more limited (and challenging) opportunity to catch with flies. But they are no less wonderful fighters, and frequently will jump after being hooked. Grass carp perhaps represent the “pinnacle” of challenge for a carp angler. I’ve written more specifically on grass carp later in this series. (Perhaps as if to suggest, “Now that you’ve got a handle on the common carp challenge, if you really want to frustrate yourself, here’s how to chase grass carp.”) For now, assume that what you’re reading is based on common carp and grass carp.

The common carp (Cyprinus carpio of the family Cyprinidae) is native to the Caspian Sea region of south-central Asia, though various subspecies are thought to have evolved in other geographic areas, from the Danube River in Europe to southeast Asia. They have been transplanted (sometimes illegally) throughout the world. In fact, they are considered among the world’s top 100 invasive species, according to the Global Invasive Species Database.

Carp earned this dubious distinction because they can live almost anywhere. Why is it that the goldfish (a type of carp) lives in the fishbowls of so many young children? Exactly, because they’re hard to kill. You don’t need to meticulously balance the pH levels in the aquarium, add a bubble wand to oxygenate the water, or keep that water in a narrow temperature range. The fishbowl just needs to have water that’s one thing–wet–for a goldfish to be able to survive in it.

It’s basically the same deal with common carp in the wild.

Carp prefer fairly temperate waters (in the 60s and 70s Fahrenheit), but they can tolerate a wide range of temperatures and water conditions. They can survive in lakes that freeze in winter, as well as in rivers and sloughs that can warm to over 90 degrees Fahrenheit. Only when waters approach the 100-degree mark will carp die–and that’s long after most other freshwater fish species would be long gone.

Carp can survive in moving currents (rivers) as well as in calm, even stagnant, ponds. The carp’s ability to survive and reproduce in relatively confined spaces is one attribute that has made it desirable for fish farming operations for centuries.

A carp’s lifespan is among the longest of any fish. Some carp have been documented to have lived for 50 years or longer, though the average lifespan of the average carp, of course, depends on water conditions, the presence of predators, food availability and other factors.

Carp “breathe” primarily with their gills, naturally, but they also have the ability to gulp air by breaching the surface and literally sucking in air with their mouths (not unlike tarpon). This is another factor that helps them persist in stagnant, less oxygenated waters.

They are also prolific breeders. The optimal water temperatures for carp to spawn are in the mid-60s Fahrenheit (not less than 62 degrees), and a typical adult female can spawn three or four times in a given year, laying as many as 300,000 eggs each time.

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This chapter is excerpted from The Orvis Guide to Fly Fishing for Carp: Tips and Tricks for the Determined Angler (2013).

Also, check out KD’s new book: A Fishable Feast: Fly Fishing and Eating Your Way Around the World–out this year and published by Rizzoli in New York. (order at Amazon, Barnes & Noble, Books-A-Million.) If you want a personalized copy with an inscription from me for yourself or a gift recipient–e.g. “to Susie, the greatest fly angler ever to grace the rivers of the Americas”–sure, I’m game. Just visit kirkdeeter.com to order and tell me what you want me to write.