Production and economics of Gangetic mystus (Mystus cavasius) farming under different feed restriction periods in cages of floodplain ecosystem

High feed cost is a major problem for the promotion of a nutrient rich fish like Gangetic mystus (Mystus cavasius) in cages under floodplain ecosystem. To address this problem, production and economics of cage farming of Gangetic mystus were evaluated under different feed restriction periods in Atrai River of Chalan Beel. Four feed restriction periods were tested in floating cages under four different treatments (T1-0 day i.e., regular feeding, T2-1 day, T3-2 days, and T4-3 days feed restriction per week). Fish were fed twice daily with commercial floating pellet containing 32% protein. Water quality parameters (water temperature, dissolved oxygen, pH and ammonia-nitrogen) were within the suitable range for fish culture. Final weight, weight gain, % weight gain, average daily gain, specific growth rate and survival rate were found significantly higher at treatment T1 whereas a better feed conversion ratio was observed in T2. Significantly higher fish production and benefit were also obtained from treatment T2. The present study concluded that Gangetic mystus with a stocking density of 50 fish m–3 fed with 32% protein containing feed maintaining 1 day feeding restriction per week are economically feasible for cage culture in running water

Evaluation of bloom dynamics and seasonal abundance of cyanobacteria in eutrophic fish culture ponds at three different regions of Bangladesh

Seasonal cycle and bloom dynamics of cyanobacteria in relation to environmental parameters were studied in three areas- Godagari Upazila under Rajshahi district (GD ponds), Bogra city (BG ponds) and Singra upazila under Natore district (SG ponds) from September 2014 to August 2015. Standard methods were followed to analyze the water quality, sediment parameters and cyanobacterial cell density. Except temperature, mean values of all water quality parameters were found significantly different (P < 0.05) among the three study sites. 7 genera of cyanobacteria were identified whereas the highest density was recorded during September in all the studied ponds in order of BG ponds (130.36×106 cells/l) > SG ponds (84.93×106 cells/l) > GD ponds (58.74×106 cells/l). Gradual decrease in cell density was observed from November to January, whereas the lowest density (12.25×106 cells/l) was recorded at BG ponds in December, 2014. Higher values of soil organic matter, total nitrogen and pH were found to play significant role in determining higher cyanobacterial cell density at BG ponds compared to SG and GB ponds. The dominant species recorded in all the three studied regions was Microcystis sp

Effects of dietary Cu nanoparticles on growth performance, physiology and bioaccumulation in Asian walking catfish (Clarias batrachus)

The present investigation was conducted to determine the optimal dietary Cu-NPs requirement of Asian walking catfish, Clarias batrachus (7.46 ± 0.15 cm; 5.28 ± 0.10 g) by feeding with diets supplemented with different concentrations of Cu-NPs (10, 20, 30, 40 and 50 mg/kg) and control group. Each experimental diet was hand-fed to triplicate groups of fish for 60 days in glass aquarium. Results showed that fish group fed with 20 mg/kg Cu-NPs in feed exhibited highest (P < 0.05) growth performance and feed utilization compared to the control group. However, increased level of Cu-NPs from 30 to 50 mg/kg in feed significantly reduced the growth performance. Significantly higher protein and lipid were also recorded at 20 mg/kg Cu-NPs supplemented group. Haematological parameters, serum lipid and enzymatic profile were found to influence significantly with the addition of Cu-NPs in feed compared to the control group. Based on the polynomial regression analysis between FW, WG and SGRW against dietary Cu-NPs levels, the optimal dietary supplementation of Cu-NPs for C. batrachus were estimated to be ranged between 19.98 to 20.05 mg/kg per diet, respectively. Bioaccumulation of Cu was the highest in liver compared to muscle and serum, whereas the highest Cu accumulation was observed at 50 mg/kg Cu-NPs supplemented group. The findings of the present study will be helpful for formulating nutrient rich low cost catfish feed

Current status of bacterial contamination in some fish species of Bakkhali river Estuary, Bangladesh

The present study aims to investigate the isolation of human pathogenic bacteria (Escherichia coli, Salmonella spp. Shigella spp. and Vibrio spp.) and in gills, intestines, skin of fishes of Bakkhali River Estuary, Cox’s Bazar. A total of 50 fish species (25 of Pomadasys hasta and 25 of Glossogobius giuris) were collected from two sampling stations namely Station-1 (Rumalia Chara) and Station-2 (Kusturi Ghat). Bacterial analyses were made by standard methods. Total heterotrophic bacterial load of the isolates was found to be lower than the recommended public health and standard. However, the highest pathogenic bacterial (E. coli, Salmonella spp. Shigella spp. and Vibrio spp.) count at Station-2 might be due to the contamination of municipal and domestic wastes and discharges from small industries that constitute the main pollution source of this estuarine river. Skin was found to be the most preferred organs for higher bacterial load compared to intestine and lower count was recorded in gills. Further research on the microbial quality assessment should be undertaken to prevent pollution of this river estuary

Heavy metal contamination and risk assessment on ecological and public health in a tropical estuarine river

Heavy metals contamination of water is one of the most severe environmental and public health issues. The present study was conducted to assess the levels of lead (Pb), chromium (Cr), cadmium (Cd), arsenic (As), copper (Cu) and zinc (Zn) in surface water of the Pasur River estuary in Bangladesh along with their health risk through the ingestion and dermal exposure. The decreasing order of studied metals was Cr > Pb >Cu > Zn > As > Cd with the mean value of 0.050 > 0.024 > 0.021 > 0.014 > 0.012 > 0.006 mg/L respectively. Pb, Cr, Cd and Zn concentration in water samples exceeded the safe limits of drinking water and thereby not safe for drinking. The multivariate analysis identified the common anthropogenic source and existence of studied metals. Heavy metal pollution index (HPI) and heavy metal evaluation index (HEI) indicated significant contamination of water. The HQ and HI through ingestion and dermal contact were <1 except for the adult, whereas HQ (only for As) and HI value through ingestion was >1 indicating an unacceptable risk of non-carcinogenic effects on public health. Carcinogenic risk through ingestion (CRing) indicated that consumption of water from Pasur River estuary may develop cancer risk of Cd. Therefore, strict rules and regulations must be adopted to reduce water contamination of this tidal river from anthropogenic sources for improving the health of this riverine ecosystem

Life-history traits of the Threatened Freshwater Fish Cirrhinus reba (Hamilton 1822) (Cypriniformes: Cyprinidae) in the Ganges River, Northwestern Bangladesh

The threatened Reba carp, Cirrhinus reba is a freshwater fish species found in ponds, rivers, canals and tanks of Bangladesh, India, Myanmar, Nepal and Pakistan. The present study describes the first complete and inclusive description of life-history traits including sex ratio, length-frequency distributions (LFD), length-weight relationships (LWR), condition factors (Allometric, KA; Fulton’s, KF; Relative condition, KR; Relative weight, WR), form factor (a3.0) and size at first sexual maturity of C. reba in the Ganges River, NW Bangladesh. Sampling was done using traditional fishing gears including cast net, square lift net and conical trap from April 2011 to March 2012. The total length (TL), fork length (FL) and standard length (SL) were measured to the nearest 0.01 cm using digital slide calipers and total body weight (BW) was measured using an electronic balance with 0.01 g accuracy. The LWR was calculated using the expression: W= a Lb, where W is the BW, L the TL. The size at first sexual maturity of C. reba was estimated using the empirical equation by Binohlan and Froese (2009) for male and female, separately. A total of 250 specimens ranging from 8.00 cm – 23.40 cm TL and 4.30 g – 200 g BW were analyzed in this study. The overall sex ratio did not differ significantly from the expected value of 1:1 (χ2 = 3.38, p 3.00) in male and female and there was significant differences in the intercepts (ancova, p< 0.001) and in the slopes (ancova, p< 0.001) between the sexes. In addition, the Mann-Whitney U-test showed significant differences in the Fulton’s condition factor between male and female (p< 0.001). The one sample t-test showed that the mean WR (actual mean = 99.50) did not differ from 100 for male (p= 0.523) and female (p= 0.197) in this study, indicating the habitat was still in good condition for C. reba. Moreover, the size at sexual maturity of male and female C. reba were estimated as 11.50 cm TL and 13.50 cm TL, respectively. The results of this study would be useful for the sustainable conservation of this threatened carp fishery in Bangladesh and also neighboring countries

Life-history traits of the freshwater garfish xenentodon cancila (Hamilton 1822) (Belonidae) in the Ganges River, Northwestern Bangladesh

The freshwater garfish, Xenentodon cancila (Hamilton 1822), is one of the commercially important, nutritionally valuable food fish in Asian countries, but the natural populations are seriously decreasing due to high fishing pressure and other factors. This study describes the life history traits, including sex ratio (SR), length-frequency distributions (LFDs), length-weight relationships (LWRs), length-length relationships (LLRs), condition factors (Allometric, KA; Fulton’s, KF; relative condition, KR; relative weight, WR) and form factor (a3.0) of X. cancila in the Ganges (Padma) River, northwestern Bangladesh. A total of 175 specimens ranging from 10.50-21.00 cm TL (total length) and 1.44-20.67 g BW (body weight) were investigated in this study. Sampling was done using traditional fishing gears from April 2011 to March 2012. The overall sex ratio showed no significant differences from the expected value of 1:1 (df = 1, χ2 = 0.28, p<0.05), whereas significant difference was found in the LFD (TL) between the sexes (Two tailed, p<0.001). The allometric coefficient b for the LWR indicated positive allometric growth in males, females and combined sexes. The results further indicated that the LLRs were highly correlated. Both KR and KF showed significant variations (Two tailed, p<0.001) between male and female. Also, WR was significantly different from 100 for both sexes (p<0.01), indicating the imbalance habitat with food availability relative to the presence of predators for X. cancila. The calculated values of a3.0 were as 0.0304, 0.0268 and 0.0252 for males, females and combined sexes of X. cancila. This study reports the first complete and comprehensive description of life-history traits for X. cancila from Bangladeshi waters. The data should be useful for the sustainable conservation of this critically endangered fishery in Bangladesh and neighboring countries

Assessment of physicochemical and bacteriological parameters in surface water of Padma River, Bangladesh

Abstract In the present study, surface water samples were collected during three seasons (summer, monsoon and winter) from four different study sites (T-dam, Padma Garden, I-dam and Talaimari point) of Padma River at Rajshahi, Bangladesh, and various physicochemical and bacterial parameters were analyzed based on standard methods. Significant differences (p < 0.05) in physicochemical parameters were observed among the seasons and sites except for water temperature. However, except for fecal coliform, other bacterial parameters such as total heterotrophic bacteria, total coliform and Vibrio cholerae counts showed significant differences (p < 0.05) among the seasons, while difference among the sites was insignificant (p < 0.05). The result also showed that all the bacterial parameters were maximum during summer and minimum during monsoon season. Untreated sewage and industrial effluents together with reduced water flow and water level were found to increase bacterial counts during summer at Site 2 (Padma Garden). Although the present situation is not serious and alarming enough, the river water requires intensive monitoring to improve its quality for better and sustainable management

Biological aspects of the critically endangered fish, Labeo boga in the Ganges River, Northwestern Bangladesh

The present study reports the first complete and inclusive description of some biological parameters including length-frequency distribution (LFD), sex ratio (SR), length-weight relationship (LWR), condition factors (allometric, KA; Fulton’s, KF; relative, KR and relative weight, WR) and form factor (a3.0) of Labeo boga in the Ganges River, northwestern Bangladesh. Sampling was conducted using traditional fishing gears during April 2011 to March 2012. For each specimen, total length (TL) was measured to the nearest 0.01 cm using digital slide calipers and total body weight (BW) was measured using an electronic balance with 0.01 g accuracy. The LWR was calculated using the expression: W= a Lb, where W is the BW and L is the TL. A total of 211 specimens ranging from 9.78-27.50 cm TL and 10.00 to 276.10 g BW were studied. BW of females was significantly higher than that of males (Mann-Whitney U-test, p>0.001). However the overall sex ratio did not differ significantly from the expected value of 1:1 (χ2 = 0.12, p<0.05). The calculated b for the LWR indicated isometric growth (» 3.00) in males, females and combined gender and there were significant differences in the intercepts but not in the slopes between the sexes of L. boga in the Ganges River. KF of females was significantly higher than that for males (p<0.001). In addition, the Wilcoxon signed rank test showed that the WR did not differ from 100 for males and females in this study indicating good condition of habitat for L. boga. The results of this study would be an effective tool for fishery specialists to initiate early management strategies and regulations for the sustainable management of the remaining stocks of this species within the Padma River and surrounding ecosystems

Dynamics of cyanobacteria planktothrix species (Oscillatoriales: Phormidiaceae) in Earthen fish ponds, Northwestern Bangladesh

The seasonal abundance, dynamics and composition of the filamentous Cyanobacteria Planktothrix spp. was studied over a 1-year period in two storm-water-fed earthen fishponds in Rajshahi city, northwestern Bangladesh. Sampling was conducted monthly using plankton net (25 μm mesh size) and the samples preserved in 5% formalin. Water quality parameters including water temperature, transparency, pH, dissolved oxygen (DO), biological oxygen demand (BOD), free carbon dioxide (CO2), nitrite-nitrogen (NO2-N), nitrate-nitrogen (NO3-N), ammonium (NH4 +), oxidation reduction index (rH2) were recorded during each sampling. Two species; Planktothrix agardhii and Planktothrix rubescens were identified during the study with P. agardhii recording higher abundance (p<0.05) all year round. The Planktothrix cell density was highest during March: 3.06×106 cells/L and 1.23×106 cells/L in Pond-1 and 2, respectively. The abundance of P. agardhii was relatively higher in spring. The cell densities increased with increasing temperature, pH, and nutrient concentration. Lower cell densities were recorded during periods of high BOD. The results of this study provide a useful guide for aquaculturists and other environmental scientists for the management of the cyanotoxin producing algal blooms of Planktothrix spp. in fertilized fish ponds and other aquatic habitats