What is carp? Carp are mainly freshwater oily (Food Standards Agency, 2004) fish species under the family Cyprinidae, a very large group of fish primarily originated from Europe and Asia. Biology of CarpCypriniformes mostly has scales and teeth on the inferior pharyngeal bones which may be modified in relation to the diet. Only the Tribolodon genus under the Cyprinidae family can tolerate salt water. Some species are catadromous and they move into brackish water but return to freshwater to spawn. The rest of the Cypriniformes live in continental waters and have a wide geographical range (Billard, 1995). Some carp species are able to survive for a few months with practically no oxygen (for example under ice) by metabolizing glycogento form ethanoland lactic acid (New Scientist, 2017). Somebody thinks that all cyprinid fishes are carp. On the other and, some consider the family Cyprinidae itself is the carp family. In colloquial use, carp usually refers only to several larger cyprinid species such as Cyprinus carpio(common carp), Labeo rohita (rohu carp), Ctenopharyngodon idella (grass carp), Hypophthalmichthys molitrix (silver carp), and Aristichthys nobilis (bighead carp). Carps in BangladeshCarps are basically the most important species to aquaculture in Bangladesh. In 2001, carp production was estimated as 89% of the total freshwater fish production in the country. Carp HatcheryThe term “Carp Hatchery” is considered in the broadest sense as a facility where carp fish fry and fingerlings suitable for stocking in growth ponds are produced in an artificial manner by the process of induced breeding technique. Induced breeding is a technique whereby ripe brood fishes are stimulated by treating them with inducing agents to breed in captivity. The stimulant promotes a timely release of eggs and milt from ripe breeders. It is now used as a widely accepted means of artificial propagation to overcome constraints in fish seed supply particularly for species that do not breed in captivity. Carp hatchery region in Bangladesh: The carp hatcheries are distributed in most parts of Bangladesh. They are Mymensingh, Khulna, Satkhira, Bagarhat, Barishal, Jhalukati, Comilla, Chandpur, Chuadanga, Dhaka, Borguna, Faridpur, Madaripur, Kushtia, Magura, Naraial, Pabna, Bogura, Rangpur, Nator, Rajshahi, Jessore and other districts of Bangladesh. Most of the hatcheries are seen Mymensingh, Jessore, Khulna, Rajshahi.Common hatchery operations in Bangladesh, most intensive hatchery and nursery activities take place during June-December, although nursery activities often extend up to February. Generally, during or after February, farmers begin their pond preparation to start the new cycle of breeding and rearing. On average, the duration of the hatching cycle in hatcheries is about five days and the number of cycles per year (June-December) is about 30. The hatchery cycle generally starts from the day when the broodstock is brought to the hatchery from the brood pond until the larvae absorb the yolk sac and the fry is transferred to the rearing pond or cement cistern from the hatching jar.Nursery rearing of carp fry and fingerlings is generally carried out in three stages: a) early fry raising (spawn-early fry), b) fry raising (early fry-fry), and c) fingerling raising (fry-fingerling). The duration of the nursery cycle varies depending on the stage of rearing. The duration of the early fry-raising cycle varies between six to eight days that of fry raising varies between 20-30 days, and that of fingerling raising between 90-100 days. On average, the total number of nursery cycles per year was 8-12. During early fry raising, spawn is raised up to 0.5-1.0 cm size; during fry raising, the fry is grown from 1.0 to 3.0 cm; while size ranges in fingerling raising vary widely between 3-15 cm.Most hatchery and nursery owners have their own broodstock and nursery ponds. Many of the nursery owners also lease ponds from villagers. The study did not reveal any major difference in the number of ponds owned by the hatchery and nursery owners in these two regions. On average, the hatcheries had eight ponds with a total pond area of 2.06 ha, and the nurseries had, on average, seven ponds with a total pond area of 1.88 ha. Combined hatcheries and nurseries were larger, with an average of 10.5 ponds and an area of 6.74 ha. Nevertheless, there was a large variation in the total area between different hatcheries and nurseries. The maximum nursing pond area was 17.8 ha, and the minimum was only 0.06 ha. Forty-two percent of the nurseries sampled had a pond area of less than 1 ha. For hatcheries, the average area of ponds was 2.23 ha, with a minimum of 0.13 ha and a maximum of 9.93 ha. Forty-five percent of hatcheries had an area of less than 1 ha. For the combined hatcheries and nurseries, the average size was greater, with an average pond area of 6.74 ha. The maximum farm size was 43.71 ha, and the minimum was 0.82 ha.The nursery owners were interviewed about their most likely sources of spawn and the hatchery owners about the sources of their broodstock. The source of spawn for nurseries was mainly from hatcheries (72.6 %); followed by wild-caught (e.g., river -13.7%), own grown (12.6%) and other farmers (0.5%). Similarly, the source of broodstock for the hatcheries was mainly from other farmers' ponds (41.3%), followed by own grown (16.3%), wild-caught (16.3%), traders (11.5%), government and private hatcheries and other sources.Induced breeding practices. The knowledge of artificial breeding is a key aspect as it permits intensive production of a given species in controlled conditions. This allows continued production of juveniles for restocking natural or artificial water bodies (Montchowui et al., 2011). When some stimulants, hormones, or pituitary extracts are injected into the brood fishes causing fish to spawn in the controlled condition out of the natural environment is called induced breeding or artificial reproduction (Bhuiyan and Aktar, 2011; Bhuiyan et al. 2008) which is a common practice in our country since 1967 (Ali, 1967). Only proper induced breeding and fry rearing techniques can ensure a steady supply of quality fish seeds.