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Delta Journal
by Bob Thomas

A rather abundant freshwater fish in our area is the common carp, Cyprinus carpio. It was introduced to the U.S. in 1831 from its native home in eastern Europe and Asia, and is now one of the most common large fish species where it occurs. In fact, the same can be said for many parts of the world where they have been introduced.

A pair of barbels at each side of the mouth and serrated spines on the dorsal and anal fins help identify this species. Specimens from our part of the world have large scales covering the body, but carp are a highly variable species worldwide. Some populations have only a few scales near the dorsal fins, and others have large mirror-like scales. Some are relatively longer with less height. Koi are a domesticated form of the species that are common in home ponds.

Carp have played an important role as a food source for humans for centuries, being raised in fish ponds (piscinae) by the ancient Romans. Though many Americans refuse to eat them, they are a vital protein source in many developing countries. They are also quite popular among American anglers since they are strong fighters.

Normally forming schools of five or more individuals, older carp tend to be solitary. Carp prefer large, slow moving bodies of water and may reach 80 lb and measure five feet in length.

Carp do better than most species in low oxygen conditions since they can gulp air.

Feeding behavior involves grubbing about in soft sediment, spitting the mud out, and gobbling up exposed critters. Carp will eat almost anything. Juveniles begin with plankton, and adults eat virtually anything that moves. They also eat vegetation.

One benefit of their feeding technique is that they serve as nutrient pumps, re-suspending nutrients that are hidden away in the soil. A down side is that they stir up the sediment, causing the water to become turbid as long as they are resident, and they disrupt vegetation as they prod the bottom for food.

During spring and summer, the males chase the females about in the vegetation, sometimes with noisy splashing. Females drop their yellowish, sticky eggs among the plants, and the males spray their milt (sperm) over them. Hatching occurs in about three days. Females may mate several times a season and lay a total of one million eggs.

During the dog days of summer, go out and fight a carp or two with a light fishing rod – and do the local environment a favor.