Commonly Practiced Induced Breeding Techniques of Carp Species in Three Important Fish Hatcheries of Kurigram District, Bangladesh

The study was carried out to investigate the induced breeding practices and variations in effective hormone dosage used in induced breeding procedures in three different fish hatcheries of Kurigram District of Bangladesh. The hatcheries mainly produced carp fish seeds, including five native fish species such as Rui (Labeo rohita), Catla (Catla catla), Mrigal (Cirrhinus mrigala), Bata (Labeo bata), Punti (Puntius sarana) and four exotic fish species namely Silver carp (Hypophthalmichthys molitrix), Bighead carp (Aristichthys nobilis), Grass carp (Ctenopharyngodon idella) and Common carp (Cyprinus carpio). Exotic carps were the highest produced fish seeds (38%) in the Kurigram district, followed by major carps (35%), Bata (16%), Punti (6%) and others (5%). Three main types of inducing agents including PG (pituitary gland), HCG (human chorionic gonadotropin) and Ovupin (GnRHa injection) were used for induced spawning. The rate of 1st dose of injection of PG, HCG, and GnRHa varied from 0.5 to 2 mg/kg body weight, 100 to 200 IU/kg body weight, and GnRHa (only one dose) 0.2 to 0.4 ml/kg body weight, respectively. The rate of 2nd dose of injection of PG varied from 2 to 12 mg/kg body weight. The PG is usually primarily used for first and second doses; the ovulation period of different fish species varied between 12 to 72 hours, whereas the hatching rate ranged from 70% to 95%. Due to the variations in inducing agents and doses, different ovulation, fertilization, and hatching rates were observed.