The experiment was conducted in the carp hatchery of the Freshwater Station, Bangladesh Fisheries Research Institute, Mymensingh during the period of October 2013 to January 2014. About 500 C. carassius fingerlings (average weight 15.66±2.11 g) were imported from China through Commerce Ministry of the People’s Republic of Bangladesh. The fish was reared up to the maturity stages (18 months) in the earthen ponds. During rearing period the fish were fed with commercial pelleted fish feed (25% protein) at the rate of 3% body weight (bw) once a day. Two hundred C. carassius matured (males and females) were selected from this imported stock. Three months prior to conduct induced breeding experiments the mature males and females broods were stocked in separate ponds during the period from October to December, 2013 and reared up to ready to spawn. Selected broods were fed with commercially available pelleted fish feed (28% protein) at the rate of 4% bw day-1 (twice a day between 9:00- 9:30 h in the morning and between 16:00- 17:00 h in the afternoon). When the fish attained ready to spawn 32 females and 32 males brood fish were selected based on physical and visual examination of secondary sexual characteristics i.e. the mature females could be easily identified by their swollen abdomen and round or oval and swollen urogenital papillae. On the other hand, the mature males were identified by their flat abdomens and long protruded genital papillae and milt was also seen when gently pressed their abdomens. Only healthy and uninjured fishes were selected for artificial breeding. The average weight of the females and males were ranged from 455-456 g and 550-568 g, respectively .Broods were collected from the brood rearing ponds in the early morning. Selected female and male broods were weighed and kept in separate cisterns for 6-8 h for conditioning before treated with PG extract. During conditioning continuous water flow was provided through inlet for aeration to ensure sufficient dissolved oxygen to the stocked brood fish in each cistern. The induced breeding experiment consisted of four different doses of PG treatments (T1, T2, T3 and T4) with three replications of each treatment. A total of 32 females and 32 males were selected for the injection. The females under each treatment were set-up under three replications indicated as R1, R2 and R3 and kept in separate cistern. The females under T1, T2, T3 and T4 were injected with PG extract at the dose of 6.0 (single dose), 6.0, 7.0 and 8.0 mg (double dose) kg-1 bw of fish, respectively. In case of males under T1, T2, T3 and T4 were injected at the dose of 2.0, 2.0, 2.5 and 3.0 mg PG kg-1 bw, respectively. For the female fish the double dose was divided into two volumes and injected at 6 h interval and the males were injected with single dose during 2nd injection of females. After ovulation, eight females and eight males from each treatment were selected for stripping. Locally available dry carp pituitary glands (PG) were collected from market in preserved condition in airtight vials. To prepare the extract for injection the required amount of PG was carefully weighed out in an analytical electronic balance. The amount of PG required was calculated on the basis of body weight of all the fish of a particular treatment to be injected using the formula as: Weight (mg) of required amount of PG (Wt) = Wb Î Pt, Where, Wb represents total body weight (kg) of all the fish to be injected; and Pt represents the rate in mg of PG to be injected kg-1 bw under a particular treatment. The total volume of the extract required was calculated by the formula as: Vol. of extract (ml) = Wt Î 1.0, Where, Wt represents the weight of PG (mg); and 1.0 represents the volume of the extract in ml to be injected kg-1 bw of fish. The weighed PG was homogenized with a small volume of distilled water and the homogenate was carefully transferred to a centrifuge tube by using distilled water to ensure complete transfer. The mixture was centrifuged for 6 min. at 6000 rpm. The freshly prepared supernatant solution of PG hormone was then slowly loaded in graduated 1.0 ml hypodermic syringe for injection. The selected brood fish were caught very carefully from the spawning tank and put on foam for injecting the PG extract to the recipient fish. The appropriate amount of diluted hormone stock solution was taken in one ml disposable syringe. A piece of clean, soft and wet cloth was used to wrap up the fish and kept lying on foam. The accurate dose of PG extract was administered at the basal part of the dorsal fin. Needle was inserted at an angle of 45° with the body. During injecting the dose was divided into two volumes and injected to the females with 6 h interval. All the males were injected only single dose during 2nd injection of females. During handling of the fish more care has taken and optimum water condition were maintained to minimize stress. In case of T1, single dose of 6.0 mg PG kg-1 bw was injected in the females while the males were injected at the rate of 2.0 PG kg-1 bw. Eight male and eight female fishes were injected. The injected male and female (1:1) were placed in separate tanks. Breeding behavior and spawning activities were observed up to ovulation time. After 6, 7, 8 and 10 h of hormonal injection, the brooders were caught and checked. No eggs can be collected from female but males were ready to release milt. Females fish under T2, T3 and T4 doses of 1.0, 1.5 and 2.0 mg PG kg-1 bw, respectively was injected as first dose, while 5.0, 5.5 and 6.0 mg PG kg-1 bw, respectively was injected as second dose at 6 h intervals. At the time of second injection of female, males under T2, T3 and T4 were injected at the dose of 2.0, 2.5 and 3.0 mg PG kg-1 bw, respectively. Eight male and eight female fishes were injected for each treatment. The injected male and female (1:1) were placed in separate spawning tanks and provided with a continuous flow of deep tube-well water through inlet of the tanks.After injection of PG the males and females under each treatment were kept in the separate cistern for stripping and the female was kept under observation to monitor if they exhibit any change in behaviour. The female were checked every hour after 2 h of 2nd injection by gently pressing their abdomen to ascertain the ovulation. A fish was considered ovulated when there were extrusions of a few eggs upon gentle pressure on the abdomen from anterior to posterior direction. The females upon ovulation were immediately stripped to collect eggs in plastic bowl. Milt from the male fish was collected by applying slight pressure on its abdomen. The eggs and milt were mixed thoroughly in the plastic bowl with a soft and clean feather. A few drops of water were added in the bowl and was shaken gently to ensure effective fertilization. To promote fertilization salt (NaCl) solution was added in the fertilized eggs. This solution was prepared by using 8.5 g NaCl in 1.0 L of water. After the use of salt solution to the eggs, it was stirred continuously for 5 minutes to mix homogeneously. The fertilized eggs were washed several times with clean water to remove the excess milt, blood etc. The swollen eggs were transferred to incubation tank. The eggs hatched out within 44 to 48 h at temperature ranged from 20.0 to 22.0°C. During incubation period, dead embryos were removed to prevent fungal growth. Number of live eggs in each group was determined within 2 to 3 h of fertilization. Percent ovulation was calculated using the formula as: ovulation (%) = (Number of fish ovulated / Total number of fish injected). A batch of approximately 100 fertilized eggs was placed in each of 3 bowls of 1.25 L capacity to determine the fertilization and hatching rates. Soon after fertilization, the embryonic development started and the fertilized eggs assumed watery appearance or slightly transparent colour while the unfertilized ones turned whitish and opaque as the time passes. Within 6 h of incubation, the numbers of fertilized and unfertilized eggs from each bowl were counted based on the colour and appearance of the eggs. The fertilized eggs began to change its size and colour from yellowish to watery and transparent while unfertized eggs turned opaque and whitish in colour. After completion of hatching, the numbers of larvae of each bowl were counted. The parameters such as percent fertilization and percent hatching were recorded as indices of the effectiveness of different PG doses: The fertilization and hatching rate was calculated as: fertilization (%) = (Number of fertilized eggs / Number of total eggs) Î 100 and hatching (%) = (Number of hatchlings / Number of fertilized eggs) Î 100. The data of the effectiveness of different PG doses viz., ovulation, fertilization and hatching rate were analyzed by MS Excel computer package as descriptive values such as mean and percentage and further tested following one way ANOVA to assess significant difference between treatment groups and then using Duncan’s New Multiple Range Test (DNMRT). The data were analyzed using statistical package through computer following Standard Methods (Zar, 1996).