The Grass Carp the only species of the genus Ctenopharyngodon idella, is a herbivorous, freshwater
fish species of family Cyprinidae. It is cultivated in China for food but was introduced in Europe
and the United States for aquatic weed control. It is a large cyprind native to Eastern Asia, with
a native range from Northern Vietnam to the Amur River on the Siberia-China border. In the United
States, the fish is also known as White Amur, in China as Waan Ue.
Description
Grass Carp or White amur, have an elongate, thick, mulletlike body form that is torpedo
shaped. The terminal mouth is slightly oblique with non-fleshy, firm lips, and no barbels. The complete
lateral line contains 40 to 42 scales. Distinct parallel grooves are located on the broad, ridged
pharyngeal teeth, that are arranged in a 2, 4-4, 2 formula. Grass carp have a short dorsal fin composed
of 7 to 10 soft branched rays. The anal fin, which is located closer to the tail than usual for a
minnow, has 7 to 11 rays and located well behind the dorsal fin. Body color is dark olive, shading to
brownish-yellow on the sides with a white belly and large slightly outlined scales. Fins are clear to
dark in color.
Grass carp have an oblong or elongated body with relatively large scales; the head is
broad and the belly rounded. The dorsal and anal fins are short with no spines and the large tail is
moderately forked. Their jaws have simple lips with no teeth and they have no barbels (whiskers). Like
other Cyprinidae, grass carp have pharyngeal teeth (in the throat). These pharyngeal teeth are in 2 rows
and enable the grass carp to cut/shred the vegetation it consumes. Their flesh is white, firm and not
oily, but the muscle mass contains �Y� bones. Grass carp flesh is considered a delicacy by
many seafood enthusiasts.
Grass carp are sometimes confused with Common Carp, but the main
difference is coloration. Grass carp have a greenish back and white abdomen, while the common variety is
orange in color. Grass carp also have a mouth shaped like a
Trout or
Bass, and Common Carp have a sticker type
mouth. The mouth is located at the end of the head and has thin, rounded lips. Grass carp do not have
any spines or whiskers and the common type do. Compared with other carp, the large eyes are set
relatively low on the head.
Habitats
This species occurs in lakes, ponds, pools and backwaters of large rivers, preferring
large, slow-flowing or standing water bodies with vegetation. It is a fish of large, turbid rivers and
associated floodplain lakes, with a wide degree of temperature tolerance. Grass carp show a high
tolerance for salinity; specimens have been known to survive for several days in water up to 3 times as
salty as sea water. In relation to water temperature, they are known to be able to adapt to water
ranging from 32 to 100 F.
Adults of the species feed primarily on aquatic plants. They feed on higher aquatic plants
and submerged terrestrial vegetation, but may also take detritus, insects, and other invertebrates.
Small grass carp prefer musk-grass over hydrilla when both plants are present, but large fish will
consume hydrilla before musk grass. Even though young fish will feed on various species of Cladophora
and Spirogyra and other filamentous algae, the grass carp is not normally considered an effective method
to control many types of algae. When the preferred food of the grass carp is not available, this fish
feeds on terrestrial vegetation hanging over the surface of the water. In fact, the name "grass carp"
comes from its unique ability to consume terrestrial grasses. Other terrestrial plants eaten by the
grass carp range from banana leaves to various dried grasses, including clippings from golf courses or
similar turf areas.
Spawning
Spawning occurs in the spring when water temperatures reach 59-63°F, and under rising
water conditions. In the wild, grass carp spawn in fast-moving rivers, and their eggs, which are
slightly heavier than water, develop while drifting downstream, kept in suspension by turbulence. The
eggs are thought to die if they sink to the bottom. Grass carp are usually thought to enter reproductive
condition and spawn at temperatures of 20 to 30°C. Eggs are semi-pelagic and must remain suspended
during the 20-40 hour incubation period. Therefore, long river stretches are usually necessary for
successful spawning.
Grass carp cannot spawn in ponds, they spawn naturally only in rivers with high water
flows and appropriate temperature. The water/current velocity must be sufficient to keep the
semi-buoyant eggs suspended as they are carried downstream. If the eggs fall to the bottom, they will
succumb to siltation and low dissolved oxygen.
Fry and early juvenile grass carp are stocked into fertilized ponds where they initially
feed on plankton and benthic invertebrates.
At 1 inch in length, grass carp start feeding on macrophytes (nonmicroscopic plants) but can and do
consume some animal foods throughout their lives.
Fishing Methods.
Fishing methods includes using medium-action spinning tackle with a single small hook
fitted with a wide variety of baits, such as corn, small dough balls, and other prepared baits. Grass
carp are timid, however, and generally will not take bait before common carp. They are more easily
fooled by a single small piece of bait, rather than a large mass. The best places to seek grass carp are
in bodies of water with a relatively limited supply of vegetation, which may prompt them to feed closer
to the surface and on non-vegetative matter. Grass carp can occasionally be caught using heavy-duty
fishing tackle and a dough-type bait (like that used for common carp). Grass carp have a habit of
staying near the surface and this makes it relatively simple to use a bow. They are strong fish that can
put up quite a fight. They are even known to occasionally jump when hooked, make repeated runs and seem
willing to do whatever they can muster to prevent being landed.
Corn is a good grasser bait (sweetcorn), but fishing it with a float close to the bank is
the best technique. They are skitish and often very gentle on the bite, so a small float helps you spot
the pull down or lift up of the bait. Some uses small cherry tomatoes on the surface too. The carp
almost surely will jump as soon as it feels the hook's sting, and it will jump several times before you
land it. Regular fishing worms without a bobber and drag it along the catfish bed and that is were you
usually find them.
