OBSERVATION ON THE INDUCED SPAWNING PRACTICES IN THE HATCHERIES OF RAJSHAHI DISTRICT OF BANGLADESH
An investigation was conducted during the period from March to December 2009 to investigate the induced spawning practices in 22 hatcheries of 6 Upazilas of Rajshahi District of Bangladesh. It was observed that, 6 native fish species viz. rui ( Labeo rohita ), catla ( Catla catla ), mrigal ( Cirrhina mrigala ), calibaush ( Labeo calbasu ), bata ( Labeo bata ), gonia ( Labeo gonius ) and six exotic fish species such as silver carp ( Hypophthalmichthys moltrix ), bighead carp ( Aristichthys nobilis ), grass carp ( Ctenopharyngodon idella ), common carp ( Cyprinus carpio ), Thai pangus ( Pangasius sutchi ), rajputi ( Puntius gonionotus ) were used in the surveyed hatcheries for induced spawning purpose. The average length limit was 41.70±13.02 to 72.81±25.98 cm, average age limit was 1.96±0.75 to 3.08±0.90 years and average weight limit was 1.83±0.79 to 7.54±3.92 kg of the brood fish. Two types of hormone injections like PG (pituitary gland) and HCG (human chorionic gonadotropin) were used for induced spawning. The rate of 1st doses of injections of PG were from 1 to 4 mg/kg and HCG from 150 to 500 IU/kg and the rate of 2nd doses of injections of PG for native and exotic species were from 4 to 8 mg/kg and 4 to 10 mg/kg respectively. The incubation period and hatching rate in different fish species varied from 10 to 72 hours and 55% to 80%, respectively. DOI: http://dx.doi.org/10.3329/jles.v6i0.9723 JLES 2011 6: 65-68
Fry production, induced breeding practices and cost-profit analysis of the hatcheries of Rajshahi district in Bangladesh
This study was conducted on the 13 hatcheries of Rajshahi district from March to December 2013 to know about the fry production status, induced breeding practices and cost-profit status. Average fry production of Labeo rohita, 93.38±83.32 kg, Catla catla, 62.00±60.84 kg, Cirrhinus cirrhosus, 77.46±58.61 kg, L. calbasu, 14.20±14.60 kg, L. bata, 53.73±50.56 kg, L. gonia, 10.00±0 kg, Heteropneustes fossilis, 5.00±0 kg, Clarias batrachus, 20.00±0 kg, Hypophthalmichthys molitrix, 149.77±138.45 kg, Aristichthys nobilis, 104.54±148.11 kg, Ctenopharyngodon idella, 19.20±15.35 kg, Cyprinus carpio 108.08±77.39 kg and Barbonymus gonionotus, 23.10±14.04 kg were recorded in the surveyed hatcheries. Two types of hormone injections PG (pituitary gland) and HCG (Human chorionic gonadotropin) were used for induced breeding. The rate of 1st dose of injection of PG varied from 1 to 2 mg/kg and HCG from 100-150 IU/kg and the rate of 2nd dose of injection of PG varied between 5 and 8 mg/kg. The incubation period and hatching rate in different fish species varied from 10 to 72 hours and 55% to 80%, respectively. The average total cost, gross return and net profit of the hatcheries were 0.667±0.798, 1.152±1.636 and 0.485±0.846 million BDT respectively.
A comparison of the potency of dopamine antagonists on spawning induction in Thai carp (Puntius gonionotus Bleeker).
The potency of three dopamine antagonists (DA) i.e., domperidone (DOM), sulpiride (SUL), and metoclopramide (MET) on spawning induction in Thai carp was compared. Sexually mature female Thai carp were injected with DOM, SUL or MET at concentrations of 5, 10, 20 or 40 mg/kg alone or in combination with the LHRH analog Buserelin (BUS) at 5 or 20 µg/kg and were allowed to spawn naturally. The results of the study showed that the three DA had the same potency when used alone. When used in combination with BUS at either low or high dosage, the order of potency of the three DA was 5 mg/kg DOM = 20 mg/kg MET = 40 mg/kg SUL. It was concluded that DOM had the highest potency on the spawning induction of the Thai carp. However, it was recommended to use 20 mg/kg MET in combination with 5 µg/kg BUS to induce spawning of mature female Thai carp, when both potency and cost were considered.