Hatcheries and Hatchery Management in Rajshahi District with Special Reference to the Induced Breeding of the Cat Fish, Clarias Batrachus (Lin.).

Abstract

Hatcheries and hatchery management in Rajshahi district with special reference to the induced breeding of the cat fish Clarias batrachus (Lin.) was studied during the period form January 2010 to December 2011. Eighteen (16 private and 2 govt.) fish hatcheries were purposively selected from Rajshahi district of Bangladesh to investigate the socio-economic condition of farm owners, limnological condition of waters, infrastructural and other facilities of hatcheries, costs and returns of hatcheries and problems and constraints involved in hatchery business. In this regard it was found that the maximum hatcheries (27.77%) were established in 1991-1995. Most of the hatchery owners (50.00%) earned their livelihood only from hatchery business. 27.78% of hatchery owners had high school level education and 27.78% had Bachelor's and Master's level education. Maximum (88.89%) hatchery operators received training about hatchery management. Most of the hatchery owners (55.56%) had own land and capital (38.89%) to establish the fish farms. They used normally van (non-mechanized vehicles) and tempo, motorcycle as mechanized vehicles to cary the fry and brood fishes. Most of the hatchery owners were satisfied for the limnological and soil condition of the hatcheries and communication (55.55%) facilities. They had both skilled and unskilled persons in hatcheries. The average monthly salary of skilled persons was 6652.174±1256.21 Taka and mean daily salary was 156.667±12.111 for unskilled person. The maximum area of the hatchery in the surveyed region was 15.0 decimals and the minimum was 3.75 decimals. Every fish hatchery owner had their own brood stock ponds and that ranged from 2 to 8. 83.37% owners reported about the seldom attack of fish diseases in their hatcheries. Most of the hatchery owners reported that they used only underground water. All the hatcheries had overhead tanks, houses/cisterns and jars/bottles. 8 hatcheries had circular hatching tanks and only 4 hatcheries had circular IV breeding tanks. They used chemicals to clean or hygiene the overhead tanks, breeding tanks, houses, jars etc. regularly. Most of the hatchery owners collected brood fishes from their own sources. They stocked 5 native species, i.e. rui (Labeo rohita), catla (Catla catla), mrigel (Cirrhina mrigala), calibaush (Labeo calbasu) and bata (Labeo bata) and 5 exotic species i.e. silver carp (Hypopthalmicthys molitrix), bighead carp (Aristicthys nobilis), grass carp ( Ctenopharyngodon idella ), common carp ( Cyprinus carpio) and raj puti (Puntius gonionotus) in a proper density and reared these with supplementary feeds. Oil cake, rice bran, boiled rice, wheat bran, blood wastage, flour, fish meal etc. were used as supplementary feeds and different fertilizers were used for brood fish rearing. Brood fishes were conditioned before induced breeding. Maximum (50.00%) hatchery owners collected eggs from brood fishes 2 times. They used PG and HCG as inducing agents. The total fry production of 18 hatcheries was 8,200 kg in 2010 and 8,380 kg in 2011. Most hatchery owners answered rui (Labeo rohita) as the most demandable species (33.33%). 50.00% fry was marketed in the Rajshahi district. Highest price of spawn was found for rui, catla and silver carp and lowest price for raj puti. The net profit was in between 2.697 lakh Taka to 7.361 lakh Taka in 2010 and in between 2.928 lakh Taka to 7.792 lakh Taka. in 2011. In general hatchery owners received highest prices of spawn at the start of season and the prices gradually dropped down to the end of the season. The production time of hatchlings normally starts in March and ends in August except common carp. It breeds all the year round. The problems of hatchery owners have been categorized into 4 types such as technical, economical, social and natural. These problems could be solved by providing soft loan to poor owners, ensuring proper training for hatchery owners/operators. The experiments on the induced breeding of the catfish, Clarias batrachus was carried out from April to July of 2010 and 2011 in two breeding seasons. Five different doses of PG (pituitary gland extract) and V HCG (human chorionic gonadotropin) hormone i.e D1 , D2, D3, D4 and Ds were applied in each month and the effect of the doses were observed on percentage of egg release, fertilization, hatching and survivability. The optimum doses were selected finally on the basis of high production of spawn. The highest response in C. batrachus was found in the months of April, May, June and July by using the PG doses of D4 at the rate of 35.00 mg/kg body weight (1st injection as 15.00 mg/kg and 2nd injection as 20.00 mg/kg body weight). So the dose D4 was found to the most effective as optimum dose. Similarly in case of HCG the best response was found in the months of April, May, June and July with the dose ofD3 at the rate of 3.00 i.u/l00g body weight. Therefore the dose D3 was selected as the optimum dose for C. batrachus in this experiment.