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

Organoleptic qualities and proximate composition of fish grown in good aquaculture practice-based carp fattening pond

Organoleptic qualities and proximate composition of fish grown in carp fattening pond were studied under three treatments of feed and fertiliser management. Treatment T1 was designed with the use of organic fertiliser and stocking of silver carp, T2 with both organic and inorganic fertilisers and silver carp and T3 with both organic and inorganic fertilisers but excluding silver carp. One day in a week feeding restriction was followed in all the treatments.  Fishes were stocked with a stocking density of 2470 fishes ha–1. Three fishes (Gibelion catla, Labeo rohita and Cirrhinus cirrhosus) were selected for organoleptic and proximate assessment. Cyanobacteria along with total phytoplankton cell density was significantly higher at treatment T2 followed by T3 and T1. However, in terms of productivity (Chl-a) treatment T2 was 27.1 and 13.3% higher compared to T1 and T3 respectively. Parameters assessed for proximate composition analysis did not vary across treatments and organoleptic test revealed comparatively higher acceptability of fishes collected from treatment T1 followed by T2 and T3 for all the fishes. Overall acceptability was higher for L. rohita from treatment T1. This study concluded that, inorganic fertilisation along with silver carp can improve the organoleptic properties of carps in pond

Determination of suitable species combination for good aquaculture practice based carp fattening in ponds under drought prone barind area of Bangladesh

Increased temperature, decreased water level and reduced culture period of the ponds with lack of guidelines in selecting appropriate stocking size, density and combination of species are major constraints for safe production of fattening based carps in drought prone barind area of Bangladesh. In order to address these problems, an experiment was conducted during July-December, 2018 to determine the suitable species combination for fattening ponds of overwintered carps in Tanore upazila (sub district) of Rajshahi district, Bangladesh. Three different combinations of surface (G. catla and H. molitrix), column (L. rohita) and bottom (C. cirrhosus and C. carpio var. specularis) feeding carp species were tested under 3 treatments (T1, T2 and T3), each with 3 replications: T1 (Surface-30%, column-40%, and bottom-30%), T2 (Surface-40%, column-30%, and bottom-30%) and T3 (Surface-35%, column-35%, and bottom-30%). Application of good aquaculture practices in the studied ponds was found to improve the environmental conditions of pond. Significantly (P< 0.05) highest fish yield was obtained from treatment T2 which was 21.47% and 11.89% higher than T1 and T3, respectively.  Significantly (P<0.05) highest cost benefit ratio was recorded with treatment T2 (0.42±0.02) followed by T3 (0.31±0.01) and T1 (0.21±0.01), respectively. Inclusion of appropriate number of fishes at different water layers of pond favoured the yield and economics of carp fattening. The study also suggests focusing on optimal stocking density together with the formulation of low cost feed for carp fattening in ponds under barind area of Bangladesh

Culture suitability of stinging catfish Heteropneustes fossilis in homestead tank: Selection of suitable stocking size

The present experiment was conducted for a period of 150 days to assess the effects of different stocking size on growth and production of stinging catfish (Heteropneustes fossilis) in three homestead cemented tanks (12×10×4 ft). Three different size groups of fish viz., 3.79±0.11, 3.09±0.13 and 2.53±0.18 cm was stocked at treatment T1, T2 and T3, respectively at a stocking density of 5000 individuals/tank each with three replications. Fish were feed twice daily with floating feed containing 35-40% protein at the rate of 15-10% for 1st 60 days, 8-6% for 2nd 60 days and 5-2.50% for rest of the culture period. The water quality parameters were within the suitable ranges for the fish culture. Mean weight gain (g) of stinging catfish was 49.03 ± 1.04, 36.72 ± 1.59 and 28.09 ± 0.41g, specific growth rate was 1.76 ± 0.02, 1.70 ± 0.04 and 1.66 ± 0.05 %/day in T1, T2 and T3, respectively. Food conversion ratio was 3.45 ± 0.82, 3.31 ± 0.10 and 3.30 ± 0.06 and survival rate were 90.67 ± 1.51, 88.20 ± 2.62 and 87.56 ± 1.26% in T1, T2 and T3, respectively. Higher stocking size also resulted in a significantly higher economic output in the form of benefit cost ratio (BCR) at T1 (2.13 ± 0.05) and the lowest at T3 (1.21 ± 0.03). The findings of the present study revealed that the highest weight gain and BCR was found in T1 which dictates that larger stocking size has a significant impact on better production

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

Spawning season and size at first sexual maturity of freshwater mussel Lamellidens marginalis (Lamarck, 1819) in the Brahmaputra River, Bangladesh

Spawning season and size at first sexual maturity of Freshwater mussel Lamellidens marginalis was studied from the specimens collected from Brahmaputra River, Mymensingh district, Bangladesh from July 2015 to June 2016. The present study has investigated sex ratios, gamogenetic cycle, condition index, and size at first sexual maturity by means of standard histological procedures. The results indicated no significant difference in the overall sex ratio (M: F = 1:1.3). The qualitative analysis of gonad developmental stages has provided confirmation of the presence of a yearly reproductive cycle characterized by prolonged gonadal activity. The highest percentages of ripe gonads were observed in July for males (77.78%) and August for females (53.85%). The spawning activity was highest in October for males (50%) and November for females (83.33%). Furthermore, ripening and spawning stages in different shell lengths ranged from 58–63 to 88–93 mm for both sexes. The findings from the qualitative observation of gonad developmental stages, a single annual spawning peak observed between October and November. A statistically significant correlation was detected between the average condition index of male and female. Males reached sexual maturity at smaller standard length (SL50 = 63.25 mm) compared to females (SL50 = 72.10 mm SL). Acquired knowledge regarding the present state and distinctive gonad developmental characteristics of L. marginalis will aid fisheries management professionals and conservation biologist in the effective management of this particular species of mussels in the waters of Bangladesh

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

Optimization of dietary protein level for good aquaculture practice based carp fattening in ponds under drought prone area of Bangladesh

Good aquaculture practice (GAP) based carp fattening is a potential technique to obtain higher and safe fish production within shorter period in ponds of drought prone area. Sustainability of this technique, however, is constrained by high feed cost and poor water quality. Therefore, as an overcoming effort, three diets (protein content of 20%, 25% and 30%) under three different treatments (T1, T2 and T3) were tested during January-June, 2020 in fattening ponds of carps (Catla, Gibelion catla; silver carp, Hypophthalmichthys molitrix; rohu, Labeo rohita; mrigal, Cirrhinus cirrhosis; and carpio, Cyprinus carpio var. specularis) under Rajshahi district, Bangladesh. Variation in protein level had no significant effect on environmental parameters of pond water. Combined fish yield was found to vary significantly (P&lt;0.05) among the treatments, while feed conversion ratio did not vary significantly. Although second degree polynomial regression analysis identified 28.50% dietary protein for optimal growth of carps but no significant difference between T2 and T3 was found for the total fish yield. However, significantly (P&lt;0.05) highest cost-benefit ratio obtained with the diet containing 25% protein suggested this protein level in diet was profitable for carp fattening in pond