Chapter 14: Carps—Cyprinidae
The family Cyprinidae, native to North America, Eurasia and Africa, contains of more than 2,400 species, which is approximately 25% of all the freshwater fish species in the world. They are cultured as food fish, sportfish, and ornamentals, and as such have been introduced into many other countries. Cyprinids are found in most freshwater habitats with some found in brackish water as well, and show a wide range in modes of reproduction. Depending on the species, mature adults range from 10 mm for Paedocypris progenetica to 300 kg for Giant Barb Catlocarpio siamensis. Hatchery techniques for several commonly cultured cyprinids are covered in sections:14.1 Common Carp, Cyprinus carpio; 14.2 Chinese Carps; and 14.3 Bait Minnows.
Common Carp is one of the most widely cultured fish in the world. It has been cultured for more than a thousand years resulting in many varieties of Common Carp differing in body shape, scale pattern, fin shape, and color. It is cultured as a food fish, as bait, and as an ornamental (Koi). Common Carp respond well to intensive culture systems, accept a wide range of natural and artificial feeds, grow rapidly to acceptable sizes, and is tolerant of a wide range of growing conditions. It can survive in both low and high temperature setting. In tropical counties with elevations of 1000–2000 m, it fits in a water temperature niche of 18–22°C where it can be too warm to culture trout but too cool for optimum Tilapia growth. Its long history of domestication, its flexibility in culture, and worldwide distribution has resulted in a number of reproduction and culture options.
Common Carp can have a long life span of >25 years and reach a weight of >40 kg. In a cool temperate climate, 3 years or longer may be required to reach sexual maturity but in a warm climate only 1 year or less is required. Under favorable growth conditions fish may not be sexually mature until reaching a weight of 1.2 to 1.4 kg. Under unfavorable growth conditions fish may reach sexual maturity at a weight of 120 g but such fish may be several years old. Common Carp are quite fecund, with the number of eggs/kg of body weight ranging from 80,000 to more than 120,000 eggs/kg.
Sexual dimorphism includes pearl organs on mature males, males being smaller than same-age females, and the papilla shape of males and females differing. The urogenital opening of males is in a slit while that of gravid females is swollen and protruding. Before and during the spawning season, males flow milt when stripped. Gravid females show noticeable ovarian distention and softening of the abdominal area just before spawning.