The original home of the carp is the watershed of the Black and Caspian Seas, but as it has become a most popular pond fish, it has slowly been dispersed all over Europe. During the past century it has also been introduced to the United States, as well as parts of Africa, Australia, and New Zealand. In the warmer parts of the USA it has multiplied exceedingly, often to the detriment of native fishes and aquatic vegetation. It can be as much as 120 cm long and can weigh over 30 kg. It has large scales, a long dorsal and a short anal fin. At the corners of the mouth it has four barbels.
The original wild form of the carp (Cyprinus carpio) has a long, cylindrical, scaly body. This lives in the Danube and some of its tributaries. Spawning takes place between May and June and the spawn sticks to water plants or to the flooded grass of the river banks. The fry lives on zooplankton and when 2 cm long, progresses to a diet of bottom- living invertebrates, whilst in thickly overgrown waters the carp also lives on water plants. In Europe, it is by far the most commercially important freshwater fish and a number of varieties of carp are pond-bred and then transplanted to rivers, reservoirs and warm lakes. The carp easily crossbreeds with the crucian carp and such hybrids have two pairs of very short barbels, grow more slowly than the carp and are usually sterile.
In recent decades, the wild form of the carp has been used in crossbreeding experiments with the cultivated forms. Such hybrids are more resistant to various infectious diseases and grow very well indeed. Crucian Carp