Rajshahi University Journal of Environmental Science, 2019
Fish farmers involved in commercial aquaculture in northwest Bangladesh is striving for ruthless ... more Fish farmers involved in commercial aquaculture in northwest Bangladesh is striving for ruthless efficiency of the system. In this process they have been selective poisoning the undesired species (!) by using quinalphos pesticides while keeping their desired species (Indian and Chinese major carps) seemingly unaffected. The study was conducted to know the impact of the use of quinalphos on zooplankton, aquatic insects, and benthos population in commercial aquaculture ponds. To know the bioaccumulation phenomena, fish were collected pre and post-treatment and analyzed for residual content of quinalphos. Zooplankton, aquatic insects, and benthos samples were collected and counted at pretreatment and after 1 day, 2 days, 5 days, 10 days, 15 days, 21 days, and 28 days after the treatment. Quinalphos was found to be bioaccumulated in fish till 10 days after use. Zooplankton was found to be impacted for a short duration and was able to regenerate within 5 days of the use of quinalphos. Aquatic insects and benthos were also affected but the loss of insect diversity was observed till the end of the observation period.
A study was conducted to know the impact of abamectin and lambda-cyhalothrin on aquatic insect, z... more A study was conducted to know the impact of abamectin and lambda-cyhalothrin on aquatic insect, zooplankton and benthos populations in commercial aquaculture ponds. Accordingly, the ponds under commercial aquaculture located in Poba upazila of Rajshahi, Bangladesh were selected that had similar and commonly accepted management practices. Abamectin and lambda-cyhalothrin were used at 0.7 and 0.5µg/liter of pond water. Water and soil samples from the pond bottom was collected for analysis. Sampling for aquatic insects, zooplankton and benthos was done before treatments and on days 1, 2, 5, 10, 15, 21 and 28 following the treatments. No fish mortality was recorded in either of these treatments. A decline of 80%, 49% and 56% respectively in water insect, zooplankton and benthos count were found in abamectin treatment. Treatment of lambda-cyhalothrin caused 93%, 60% and 79% decline respectively in water insect, zooplankton and benthos numbers. Along with the decline in number, diversity loss for aquatic insects and zooplankton was also observed in both treatments. Diversity count did not recover to the pretreatment level within the observation period of 28 days.
Agricultural pyrethroid insecticides especially cypermethrin and deltamethrin are being used regu... more Agricultural pyrethroid insecticides especially cypermethrin and deltamethrin are being used regularly for the control of aquatic insects in commercial carp aquaculture ponds in northwest Bangladesh. Thisstudy was conducted in a farmer's ponds under commercial aquaculture to know the impact of cypermethrin and deltamethrin on aquatic invertebrates (insects, zooplanktons and benthos). Commercial aquaculture ponds were treated with cypermethrin and deltamethrin @ 5 µg (active ingredient)/liter pond water in presence of fish. Required amount of each of the insecticides were diluted with water in big aluminium pots and broadcasted over the pond water. Water quality parameters of the experimental ponds were measured at pretreatment stage. Sampling of aquatic invertebrates was done pretreatment and after 1 day, 2 days, 5 days, 10 days, 15 days, 21days and 28 days of the application of insecticides. No fish mortality was recorded after the treatment. Aquatic insect population was found to be most affected;number count declined89.87% and 86.24% for cypermethrin and deltamethrin respectively within one day after treatment. The insect count recovery began after day 10 and day 5 of cypermethrin and deltamethr in treatment respectively. Loss of insect diversity was observed in cypermethrin treatment and diversity count did not recover within observation period of 28 days.Zooplankton populatio nwas relatively less impacted (21.10% and 26.33% declined respectively in cypermethrin and deltamethrin treatment). Benthos population count and diversity was not affected, possibly due to the high organic carbon content and clay soil of the pond bottom.
Parasitic infestation of carp fish is a major challenge for commercial fish farmers of northwest ... more Parasitic infestation of carp fish is a major challenge for commercial fish farmers of northwest Bangladesh. Commercial fish farmers of this region are using emamectin benzoate (a plant pesticide) for water treatment of parasite infested fish ponds. The study was conducted to know the practice of using emamectin benzoate (water treatment at the rate of 2µg/L pond water and feed at the rate of 50µg/kg fish for seven consecutive days) impact on zooplanktons, aquatic insects and benthos population in aquaculture ponds. Regular sampling of zooplanktons, aquatic insects and benthos were done and counted at pretreatment and after 1, 2, 5, 10, 15, 21 and 28 days of the treatment for both methods of treatment. Though both the feeding and water treatment with emamectin benzoate was found to be equally successful in killing the target fish parasites, however, the unintended impact of the water treatment was found to be huge on zooplanktons and benthos population. Aquatic insects were also found to be affected partially. Moreover, choice of application method creates a great difference (water treatment requires many times more) in amount of total emamectin benzoate required for the treatment and ultimately used in the water body.
A study was conducted to assess fish catch in the Baila beel of Maljhee-Kangsa floodplain in the ... more A study was conducted to assess fish catch in the Baila beel of Maljhee-Kangsa floodplain in the north-central part of Bangladesh. A total of 7 types of fishing gear were found in use by the fishermen which are: push net, gill net, cast net, lift net, current net, fish traps and hooks. The duration of fishing depends on use of fishing gear, season, habitat type, water depth, and abundance of fishes. From the survey it was found that the highest average fishing time was estimated in fish trap (18.04 h/day) and the lowest in push net (3.21 h/day). There are variations in the Catch Per Unit of Effort (CPUE) of different gears in different seasons. The highest and the lowest CPUE were recorded in current net and hook which were 0.31 and 0.02 kg/gear/h, respectively. According the fishermen, the highest catch was obtained during the receding of floodwater in post-monsoon season (October-December) and the lowest during the pre-monsoon season (April-June). A total of 39 fish species were identified in the catches of different gears. From the survey it was found that a fisherman daily catches an average 1.43 kg of fish. Alarmingly the catch of fish has declined b an estimated 20% in the past five years. Concerns arise about the sustainable catches due to overfishing and indiscriminate use of gears. It is therefore necessary to provide institutional and organizational supports for artificial stocking and establishing fish sanctuaries through active community participation for sustainable catches.
Most of the rural people of Bangladesh are under nourished due to lack of protein supplement in t... more Most of the rural people of Bangladesh are under nourished due to lack of protein supplement in their diet thought many of them possess some resources such as ponds. Sustainable and integrated using of pond (poultry-cum fish culture) may change their conditions. The study was conducted to determine whether broiler (strain: Arber Acres) and duck (Anas platyrhynchos) is better for integration with fish. Poultry sheds were raised on 6 seasonal ponds. Poultry and fishes were stocked in ponds and cultured for 145 days. Our observation shows Broilers are more suitable than ducks for integration with fish in seasonal ponds, though in both treatment fish production was more or less similar, 972.05 kg/acre and 958.77 kg/acre. However, integration with ducks resulted in a net loss of TK. 16,093. 38/acre due to heavy loss in duck culture (Tk. 61,726.20/acre), it is because in relation to cost for duck (Tk. 117,318. 70/acre), the return was very low (Tk. 55,592. 50/acre). On the other hand, the net profit in integration with broiler was Tk. 9,92,776.74/acre. As the culture period was short (ponds were seasonal), very few eggs were obtained from ducks and also ducks were confined like as broilers to they needed large amount of food resulting in high operating cost- may be the two reasons of being unprofitable.
Inclusion of chicken in rice-fish system facilitates more fish in the culture due to available ex... more Inclusion of chicken in rice-fish system facilitates more fish in the culture due to available excreta and excess feed of poultry. To optimize the fish stocking density in the system, 4446/ha and 6669/ha fish seed was stocked. Higher fish production (1609.6 kg/ha) as well as higher net return (112077.9 Tk/ha/cropping season) was obtained from where fish-stocking density was higher. A negative co-relation (r=-0.5145) was found between fish stocking density and rice yield.
This paper describes the feminization of GIFT, Oreochromis niloticus using diethylstilbestrol (DE... more This paper describes the feminization of GIFT, Oreochromis niloticus using diethylstilbestrol (DES) with a future plan to produce YY male. The feminized XY female has ability to produce 25% YY male offspring upon mating with normal male (XY). The genotype of YY male can be separated from the normal XY male through progeny testing. In order to determine a suitable dose of feminization, five different doses of DES such as 0, 50, 100, 150 and 200 mg of hormone were mixed with per kg of feed and fed the fry for a period of 30 days. The sex ratio analysis showed that treatments of 150 mg/kg and 200 mg/kg had produced 100% female progeny. The treatments of 50 mg/kg and 100 mg/kg produced 95% and 90% female progeny respectively, however, they are significantly different (P<0.01) from 1:1 female: male sex ratio. A high rate of mortality was found in all the treatments including the control (ranging 54.25% to 75.5%) and it was happened more in higher doses during the first 10 days of experiment.
Genetically Improved Farmed Tilapia (GIFT) is one of the most successful one of all exotic fish s... more Genetically Improved Farmed Tilapia (GIFT) is one of the most successful one of all exotic fish species in Bangladesh from the view of acceptance and prevalence in cultured water bodies. Manual separation of male and female tilapia is one of the methods for obtaining single sex. In Bangladesh, abundance of sex reversed GIFT male is very limited, therefore, the experiment was conducted to compare the yield of manually separated GIFT with others. Highest yield (5285.3±289.9 kg haG) and gross return (358343.7±23555.6 tk haG) were found 1 1 from manually separated male GIFT, which was significantly different from others. Even manually separated female GIFT gave the better production than culture of both sexes together and of carps also.
The present study concerned about the fish marketing systems in Gazipur, based on existing market... more The present study concerned about the fish marketing systems in Gazipur, based on existing marketing systems, economic features of marketing activities and inefficiencies. In Gazipur, fish marketing is almost exclusively a preserve of the private sector where livelihoods of a large number of people are associated with fish distribution and marketing systems. The market chain from producers to consumers passes through a number of intermediaries: local traders, agents/suppliers, wholesalers and retailers. Based on a sample of 40 traders from the two different markets in Gazipur district, the daily supply of fish market in Gazipur Sadar and Sripur markets were estimated at 2-3 and 1-1.5 tonnes, respectively. Virtually most of the fish (80%) is imported from outside, the local supply amount only 20%. It is estimated that 48% of fish supplied in markets is of carps, 13% hilsa, 9% catfish, 7% small indigenous fish, 6% prawn and shrimp, 5% tilapia and 12% others including marine fish. The price of fish depends on market structure, species quality, size and weight and it was found that the price per kilogram of carp increases with size. All traders in two markets made a considerable amount of profit.
A series of experiments were conducted to produce YY-supermale GIFT strain of tilapia
in Banglade... more A series of experiments were conducted to produce YY-supermale GIFT strain of tilapia in Bangladesh first, through optimization of feminizing hormone, Diethylstilbestrol (DES) to produce 100% female tilapia. The feminized female tilapia (XY) obtained from 150 mg/kg feed treatment were reared, tagged and bred individually. About 36% (4 out of 11 fish) of the treated fish became sex reversed female and it was confirmed by sexing their offspring, produced through crossing with genotypic male (XY), using aceto-carmine gonad squashing method that resulted in 75% male and 25% female. Since the 75% male offspring are supposed to contain 25% YY male, half of the offspring of each sex reversed females were feminized using DES at the same dose (150 mg/kg feed) to produce YY female by reversing the sex of the 25% YY male offspring. The stock that contained 75% male offspring was kept as it contained theoretically 25% YY male. The other half of the same stock (feminized half) that contained 25% YY female was also kept. Then the all of the individual male and female of such stocks were bred individually and identified the individual YY male and YY female by observing the sex ratio of their offspring as YY male or YY female that produced 100% genotypic male offspring in mating with genotypic female and male, respectively. A total of 106 fish from the non-feminized stocks were bred, 15 of them were identified as YY male but only 4 fish produced 100% male and the rest produced 80.12% to 97.18% male. Similarly, 45 fish from the feminized stocks were bred, 8 of them were identified as YY female but 3 of them produced 100% male and the rest produced 93.33% to 97.77% male. Finally the identified YY males and YY females were crossed to produce 100% YY supermales and thus the objectives were achieved.
Rajshahi University Journal of Environmental Science, 2018
Tilapia (Oreochromis niloticus) is one of the most cultured species in Bangladesh. For many pract... more Tilapia (Oreochromis niloticus) is one of the most cultured species in Bangladesh. For many practical reasons, almost all tilapia fry used in commercial tilapia culture are sex inversed male obtained by feeding of 17-alpha methyltestosterone. Sometimes methyltestosterone is also fed as growth promoter during growth stage of tilapia. The study was conducted to compare the serum testosterone level of sex inversed tilapia (marketable size) with the normal tilapia population and observe the effect of methyltestosterone feeding as growth promoter on serum testosterone level of adult tilapia. For the first objective, blood samples from both sex-inversed and normal tilapia were collected and serum testosterone level were determined using ELISA test kit. For the second objective, normal adult male and female tilapia were fed with feed (at the rate of 3% of body weight daily) containing 10 mg/kg methyltestosterone over the period of one month and blood serum testosterone level were determined at various point during feeding and up to another month after stopped feeding of the hormone. In this study, no significant difference in serum testosterone level was found in between adult sex inversed and normal tilapia (for both male and female). However, serum testosterone level was found to be several times higher than the normal population when methyltestosterone was fed as growth promoter and high serum testosterone level continued up to the end of the experiment (after one month of stopped feeding). Feeding methyltestosterone as growth promoter also triggered higher rate of reproduction of tilapia in cages.
Asian-Australasian Journal of Food Safety and Security, 2019
Use of fish toxicants is an important management tool in inland commercial aquaculture. In entrep... more Use of fish toxicants is an important management tool in inland commercial aquaculture. In entrepreneurial fishery in northwest Bangladesh where pond ownership (using rights due to lease) changes frequently (every few years) use of fish toxicants is very routine and more crucial. Along with some traditional fish toxicants (rotenone and aluminium phosphide), unconventional and insecticides like fenpropathrin (not approved for aquaculture use) are being used by fish farm owners in northwest Bangladesh. The study was conducted to understand the consequences of use of fenpropathrin compared to other traditional fish toxicants in commercial aquaculture for harvesting of food fish. Of all the toxicants, fenpropathrin' s impact was lowest on zooplankton and aquatic insect population, while rotenone had the lowest impact on benthos population in terms of killing and quick recovery time for the population, primarily due to the high turbidity (suspended soil particle) of the pond water (under this study) by which both fenpropathrin and rotenone got affected. Aluminium phosphide found to be more damaging in terms of killing and relatively longer recovery time for zooplankton, aquatic insect and benthos population. Using convenience, quick killing, cheaper price, short duration of toxicity and no potential long-term damage of the waterbody contributes positively for fenpropathrin as fish toxicant except the severe potential public health concern from eating of fish killed by fenpropathrin due to very high bioconcentration factor of fenpropathrin; hence, demands regulation of fenpropathrin' s use as fish toxicants for food fish.
Rajshahi University Journal of Environmental Science, 2019
Fish farmers involved in commercial aquaculture in northwest Bangladesh is striving for ruthless ... more Fish farmers involved in commercial aquaculture in northwest Bangladesh is striving for ruthless efficiency of the system. In this process they have been selective poisoning the undesired species (!) by using quinalphos pesticides while keeping their desired species (Indian and Chinese major carps) seemingly unaffected. The study was conducted to know the impact of the use of quinalphos on zooplankton, aquatic insects, and benthos population in commercial aquaculture ponds. To know the bioaccumulation phenomena, fish were collected pre and post-treatment and analyzed for residual content of quinalphos. Zooplankton, aquatic insects, and benthos samples were collected and counted at pretreatment and after 1 day, 2 days, 5 days, 10 days, 15 days, 21 days, and 28 days after the treatment. Quinalphos was found to be bioaccumulated in fish till 10 days after use. Zooplankton was found to be impacted for a short duration and was able to regenerate within 5 days of the use of quinalphos. Aquatic insects and benthos were also affected but the loss of insect diversity was observed till the end of the observation period.
A study was conducted to know the impact of abamectin and lambda-cyhalothrin on aquatic insect, z... more A study was conducted to know the impact of abamectin and lambda-cyhalothrin on aquatic insect, zooplankton and benthos populations in commercial aquaculture ponds. Accordingly, the ponds under commercial aquaculture located in Poba upazila of Rajshahi, Bangladesh were selected that had similar and commonly accepted management practices. Abamectin and lambda-cyhalothrin were used at 0.7 and 0.5µg/liter of pond water. Water and soil samples from the pond bottom was collected for analysis. Sampling for aquatic insects, zooplankton and benthos was done before treatments and on days 1, 2, 5, 10, 15, 21 and 28 following the treatments. No fish mortality was recorded in either of these treatments. A decline of 80%, 49% and 56% respectively in water insect, zooplankton and benthos count were found in abamectin treatment. Treatment of lambda-cyhalothrin caused 93%, 60% and 79% decline respectively in water insect, zooplankton and benthos numbers. Along with the decline in number, diversity loss for aquatic insects and zooplankton was also observed in both treatments. Diversity count did not recover to the pretreatment level within the observation period of 28 days.
Agricultural pyrethroid insecticides especially cypermethrin and deltamethrin are being used regu... more Agricultural pyrethroid insecticides especially cypermethrin and deltamethrin are being used regularly for the control of aquatic insects in commercial carp aquaculture ponds in northwest Bangladesh. Thisstudy was conducted in a farmer's ponds under commercial aquaculture to know the impact of cypermethrin and deltamethrin on aquatic invertebrates (insects, zooplanktons and benthos). Commercial aquaculture ponds were treated with cypermethrin and deltamethrin @ 5 µg (active ingredient)/liter pond water in presence of fish. Required amount of each of the insecticides were diluted with water in big aluminium pots and broadcasted over the pond water. Water quality parameters of the experimental ponds were measured at pretreatment stage. Sampling of aquatic invertebrates was done pretreatment and after 1 day, 2 days, 5 days, 10 days, 15 days, 21days and 28 days of the application of insecticides. No fish mortality was recorded after the treatment. Aquatic insect population was found to be most affected;number count declined89.87% and 86.24% for cypermethrin and deltamethrin respectively within one day after treatment. The insect count recovery began after day 10 and day 5 of cypermethrin and deltamethr in treatment respectively. Loss of insect diversity was observed in cypermethrin treatment and diversity count did not recover within observation period of 28 days.Zooplankton populatio nwas relatively less impacted (21.10% and 26.33% declined respectively in cypermethrin and deltamethrin treatment). Benthos population count and diversity was not affected, possibly due to the high organic carbon content and clay soil of the pond bottom.
Parasitic infestation of carp fish is a major challenge for commercial fish farmers of northwest ... more Parasitic infestation of carp fish is a major challenge for commercial fish farmers of northwest Bangladesh. Commercial fish farmers of this region are using emamectin benzoate (a plant pesticide) for water treatment of parasite infested fish ponds. The study was conducted to know the practice of using emamectin benzoate (water treatment at the rate of 2µg/L pond water and feed at the rate of 50µg/kg fish for seven consecutive days) impact on zooplanktons, aquatic insects and benthos population in aquaculture ponds. Regular sampling of zooplanktons, aquatic insects and benthos were done and counted at pretreatment and after 1, 2, 5, 10, 15, 21 and 28 days of the treatment for both methods of treatment. Though both the feeding and water treatment with emamectin benzoate was found to be equally successful in killing the target fish parasites, however, the unintended impact of the water treatment was found to be huge on zooplanktons and benthos population. Aquatic insects were also found to be affected partially. Moreover, choice of application method creates a great difference (water treatment requires many times more) in amount of total emamectin benzoate required for the treatment and ultimately used in the water body.
A study was conducted to assess fish catch in the Baila beel of Maljhee-Kangsa floodplain in the ... more A study was conducted to assess fish catch in the Baila beel of Maljhee-Kangsa floodplain in the north-central part of Bangladesh. A total of 7 types of fishing gear were found in use by the fishermen which are: push net, gill net, cast net, lift net, current net, fish traps and hooks. The duration of fishing depends on use of fishing gear, season, habitat type, water depth, and abundance of fishes. From the survey it was found that the highest average fishing time was estimated in fish trap (18.04 h/day) and the lowest in push net (3.21 h/day). There are variations in the Catch Per Unit of Effort (CPUE) of different gears in different seasons. The highest and the lowest CPUE were recorded in current net and hook which were 0.31 and 0.02 kg/gear/h, respectively. According the fishermen, the highest catch was obtained during the receding of floodwater in post-monsoon season (October-December) and the lowest during the pre-monsoon season (April-June). A total of 39 fish species were identified in the catches of different gears. From the survey it was found that a fisherman daily catches an average 1.43 kg of fish. Alarmingly the catch of fish has declined b an estimated 20% in the past five years. Concerns arise about the sustainable catches due to overfishing and indiscriminate use of gears. It is therefore necessary to provide institutional and organizational supports for artificial stocking and establishing fish sanctuaries through active community participation for sustainable catches.
Most of the rural people of Bangladesh are under nourished due to lack of protein supplement in t... more Most of the rural people of Bangladesh are under nourished due to lack of protein supplement in their diet thought many of them possess some resources such as ponds. Sustainable and integrated using of pond (poultry-cum fish culture) may change their conditions. The study was conducted to determine whether broiler (strain: Arber Acres) and duck (Anas platyrhynchos) is better for integration with fish. Poultry sheds were raised on 6 seasonal ponds. Poultry and fishes were stocked in ponds and cultured for 145 days. Our observation shows Broilers are more suitable than ducks for integration with fish in seasonal ponds, though in both treatment fish production was more or less similar, 972.05 kg/acre and 958.77 kg/acre. However, integration with ducks resulted in a net loss of TK. 16,093. 38/acre due to heavy loss in duck culture (Tk. 61,726.20/acre), it is because in relation to cost for duck (Tk. 117,318. 70/acre), the return was very low (Tk. 55,592. 50/acre). On the other hand, the net profit in integration with broiler was Tk. 9,92,776.74/acre. As the culture period was short (ponds were seasonal), very few eggs were obtained from ducks and also ducks were confined like as broilers to they needed large amount of food resulting in high operating cost- may be the two reasons of being unprofitable.
Inclusion of chicken in rice-fish system facilitates more fish in the culture due to available ex... more Inclusion of chicken in rice-fish system facilitates more fish in the culture due to available excreta and excess feed of poultry. To optimize the fish stocking density in the system, 4446/ha and 6669/ha fish seed was stocked. Higher fish production (1609.6 kg/ha) as well as higher net return (112077.9 Tk/ha/cropping season) was obtained from where fish-stocking density was higher. A negative co-relation (r=-0.5145) was found between fish stocking density and rice yield.
This paper describes the feminization of GIFT, Oreochromis niloticus using diethylstilbestrol (DE... more This paper describes the feminization of GIFT, Oreochromis niloticus using diethylstilbestrol (DES) with a future plan to produce YY male. The feminized XY female has ability to produce 25% YY male offspring upon mating with normal male (XY). The genotype of YY male can be separated from the normal XY male through progeny testing. In order to determine a suitable dose of feminization, five different doses of DES such as 0, 50, 100, 150 and 200 mg of hormone were mixed with per kg of feed and fed the fry for a period of 30 days. The sex ratio analysis showed that treatments of 150 mg/kg and 200 mg/kg had produced 100% female progeny. The treatments of 50 mg/kg and 100 mg/kg produced 95% and 90% female progeny respectively, however, they are significantly different (P<0.01) from 1:1 female: male sex ratio. A high rate of mortality was found in all the treatments including the control (ranging 54.25% to 75.5%) and it was happened more in higher doses during the first 10 days of experiment.
Genetically Improved Farmed Tilapia (GIFT) is one of the most successful one of all exotic fish s... more Genetically Improved Farmed Tilapia (GIFT) is one of the most successful one of all exotic fish species in Bangladesh from the view of acceptance and prevalence in cultured water bodies. Manual separation of male and female tilapia is one of the methods for obtaining single sex. In Bangladesh, abundance of sex reversed GIFT male is very limited, therefore, the experiment was conducted to compare the yield of manually separated GIFT with others. Highest yield (5285.3±289.9 kg haG) and gross return (358343.7±23555.6 tk haG) were found 1 1 from manually separated male GIFT, which was significantly different from others. Even manually separated female GIFT gave the better production than culture of both sexes together and of carps also.
The present study concerned about the fish marketing systems in Gazipur, based on existing market... more The present study concerned about the fish marketing systems in Gazipur, based on existing marketing systems, economic features of marketing activities and inefficiencies. In Gazipur, fish marketing is almost exclusively a preserve of the private sector where livelihoods of a large number of people are associated with fish distribution and marketing systems. The market chain from producers to consumers passes through a number of intermediaries: local traders, agents/suppliers, wholesalers and retailers. Based on a sample of 40 traders from the two different markets in Gazipur district, the daily supply of fish market in Gazipur Sadar and Sripur markets were estimated at 2-3 and 1-1.5 tonnes, respectively. Virtually most of the fish (80%) is imported from outside, the local supply amount only 20%. It is estimated that 48% of fish supplied in markets is of carps, 13% hilsa, 9% catfish, 7% small indigenous fish, 6% prawn and shrimp, 5% tilapia and 12% others including marine fish. The price of fish depends on market structure, species quality, size and weight and it was found that the price per kilogram of carp increases with size. All traders in two markets made a considerable amount of profit.
A series of experiments were conducted to produce YY-supermale GIFT strain of tilapia
in Banglade... more A series of experiments were conducted to produce YY-supermale GIFT strain of tilapia in Bangladesh first, through optimization of feminizing hormone, Diethylstilbestrol (DES) to produce 100% female tilapia. The feminized female tilapia (XY) obtained from 150 mg/kg feed treatment were reared, tagged and bred individually. About 36% (4 out of 11 fish) of the treated fish became sex reversed female and it was confirmed by sexing their offspring, produced through crossing with genotypic male (XY), using aceto-carmine gonad squashing method that resulted in 75% male and 25% female. Since the 75% male offspring are supposed to contain 25% YY male, half of the offspring of each sex reversed females were feminized using DES at the same dose (150 mg/kg feed) to produce YY female by reversing the sex of the 25% YY male offspring. The stock that contained 75% male offspring was kept as it contained theoretically 25% YY male. The other half of the same stock (feminized half) that contained 25% YY female was also kept. Then the all of the individual male and female of such stocks were bred individually and identified the individual YY male and YY female by observing the sex ratio of their offspring as YY male or YY female that produced 100% genotypic male offspring in mating with genotypic female and male, respectively. A total of 106 fish from the non-feminized stocks were bred, 15 of them were identified as YY male but only 4 fish produced 100% male and the rest produced 80.12% to 97.18% male. Similarly, 45 fish from the feminized stocks were bred, 8 of them were identified as YY female but 3 of them produced 100% male and the rest produced 93.33% to 97.77% male. Finally the identified YY males and YY females were crossed to produce 100% YY supermales and thus the objectives were achieved.
Rajshahi University Journal of Environmental Science, 2018
Tilapia (Oreochromis niloticus) is one of the most cultured species in Bangladesh. For many pract... more Tilapia (Oreochromis niloticus) is one of the most cultured species in Bangladesh. For many practical reasons, almost all tilapia fry used in commercial tilapia culture are sex inversed male obtained by feeding of 17-alpha methyltestosterone. Sometimes methyltestosterone is also fed as growth promoter during growth stage of tilapia. The study was conducted to compare the serum testosterone level of sex inversed tilapia (marketable size) with the normal tilapia population and observe the effect of methyltestosterone feeding as growth promoter on serum testosterone level of adult tilapia. For the first objective, blood samples from both sex-inversed and normal tilapia were collected and serum testosterone level were determined using ELISA test kit. For the second objective, normal adult male and female tilapia were fed with feed (at the rate of 3% of body weight daily) containing 10 mg/kg methyltestosterone over the period of one month and blood serum testosterone level were determined at various point during feeding and up to another month after stopped feeding of the hormone. In this study, no significant difference in serum testosterone level was found in between adult sex inversed and normal tilapia (for both male and female). However, serum testosterone level was found to be several times higher than the normal population when methyltestosterone was fed as growth promoter and high serum testosterone level continued up to the end of the experiment (after one month of stopped feeding). Feeding methyltestosterone as growth promoter also triggered higher rate of reproduction of tilapia in cages.
Asian-Australasian Journal of Food Safety and Security, 2019
Use of fish toxicants is an important management tool in inland commercial aquaculture. In entrep... more Use of fish toxicants is an important management tool in inland commercial aquaculture. In entrepreneurial fishery in northwest Bangladesh where pond ownership (using rights due to lease) changes frequently (every few years) use of fish toxicants is very routine and more crucial. Along with some traditional fish toxicants (rotenone and aluminium phosphide), unconventional and insecticides like fenpropathrin (not approved for aquaculture use) are being used by fish farm owners in northwest Bangladesh. The study was conducted to understand the consequences of use of fenpropathrin compared to other traditional fish toxicants in commercial aquaculture for harvesting of food fish. Of all the toxicants, fenpropathrin' s impact was lowest on zooplankton and aquatic insect population, while rotenone had the lowest impact on benthos population in terms of killing and quick recovery time for the population, primarily due to the high turbidity (suspended soil particle) of the pond water (under this study) by which both fenpropathrin and rotenone got affected. Aluminium phosphide found to be more damaging in terms of killing and relatively longer recovery time for zooplankton, aquatic insect and benthos population. Using convenience, quick killing, cheaper price, short duration of toxicity and no potential long-term damage of the waterbody contributes positively for fenpropathrin as fish toxicant except the severe potential public health concern from eating of fish killed by fenpropathrin due to very high bioconcentration factor of fenpropathrin; hence, demands regulation of fenpropathrin' s use as fish toxicants for food fish.
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Papers by Dr. Md. Mokhlesur Rahman
in Bangladesh first, through optimization of feminizing hormone, Diethylstilbestrol (DES) to
produce 100% female tilapia. The feminized female tilapia (XY) obtained from 150 mg/kg feed
treatment were reared, tagged and bred individually. About 36% (4 out of 11 fish) of the treated
fish became sex reversed female and it was confirmed by sexing their offspring, produced
through crossing with genotypic male (XY), using aceto-carmine gonad squashing method that
resulted in 75% male and 25% female. Since the 75% male offspring are supposed to contain
25% YY male, half of the offspring of each sex reversed females were feminized using DES at
the same dose (150 mg/kg feed) to produce YY female by reversing the sex of the 25% YY male
offspring. The stock that contained 75% male offspring was kept as it contained theoretically
25% YY male. The other half of the same stock (feminized half) that contained 25% YY female
was also kept. Then the all of the individual male and female of such stocks were bred
individually and identified the individual YY male and YY female by observing the sex ratio of
their offspring as YY male or YY female that produced 100% genotypic male offspring in
mating with genotypic female and male, respectively. A total of 106 fish from the non-feminized
stocks were bred, 15 of them were identified as YY male but only 4 fish produced 100% male
and the rest produced 80.12% to 97.18% male. Similarly, 45 fish from the feminized stocks were
bred, 8 of them were identified as YY female but 3 of them produced 100% male and the rest
produced 93.33% to 97.77% male. Finally the identified YY males and YY females were crossed
to produce 100% YY supermales and thus the objectives were achieved.
in Bangladesh first, through optimization of feminizing hormone, Diethylstilbestrol (DES) to
produce 100% female tilapia. The feminized female tilapia (XY) obtained from 150 mg/kg feed
treatment were reared, tagged and bred individually. About 36% (4 out of 11 fish) of the treated
fish became sex reversed female and it was confirmed by sexing their offspring, produced
through crossing with genotypic male (XY), using aceto-carmine gonad squashing method that
resulted in 75% male and 25% female. Since the 75% male offspring are supposed to contain
25% YY male, half of the offspring of each sex reversed females were feminized using DES at
the same dose (150 mg/kg feed) to produce YY female by reversing the sex of the 25% YY male
offspring. The stock that contained 75% male offspring was kept as it contained theoretically
25% YY male. The other half of the same stock (feminized half) that contained 25% YY female
was also kept. Then the all of the individual male and female of such stocks were bred
individually and identified the individual YY male and YY female by observing the sex ratio of
their offspring as YY male or YY female that produced 100% genotypic male offspring in
mating with genotypic female and male, respectively. A total of 106 fish from the non-feminized
stocks were bred, 15 of them were identified as YY male but only 4 fish produced 100% male
and the rest produced 80.12% to 97.18% male. Similarly, 45 fish from the feminized stocks were
bred, 8 of them were identified as YY female but 3 of them produced 100% male and the rest
produced 93.33% to 97.77% male. Finally the identified YY males and YY females were crossed
to produce 100% YY supermales and thus the objectives were achieved.