Chlorella ellipsoidea is a freshwater green microalga that has great prospect for the sustainable development of aquaculture industry. Microalgae require optimal lighting conditions for efficient photosynthesis. The key to cost-effective algal biomass production is to optimize algae growth conditions. This study aimed to investigate the effects of various wavelengths viz. white (380–750 nm), green (510 nm), blue (475 nm), and red (650 nm) light-emitting diodes (LEDs) on the growth, pigment content (chlorophyll-a, chlorophyll-b, and β-carotene), and proximate composition of C. ellipsoidea with a photoperiod of 12 h:12 h light: dark cycle under indoor environmental conditions. C. ellipsoidea was cultured in Bold's Basal Medium for 18 days. The cell density (125.36×10⁵ cells ml⁻¹), cell dry weight (58.9 ± 4.57 mg L⁻¹), optical density (1.66 ± 0.08 g L⁻¹), chlorophyll-a (7.31 ± 0.04 μg ml⁻¹), chlorophyll-b (2.73 ± 0.13 μg ml⁻¹), and β-carotene (0.39 ± 0.04 μg ml⁻¹) content of C. ellipsoidea were significantly (P < 0.05) higher at 15^th-day when cultured under blue LED light exposure. Significantly lower growth and nutritional values were obtained under red LED light exposure compared to the control and other LEDs spectra. In Pearson correlation analysis, the cell density and cell dry weight values showed a strong positive correlation with the values of pigment contents of C. ellipsoidea in all the treatments. The LEDs light spectra showed significant effects on proximate composition of C. ellipsoidea. Protein and lipid contents of C. ellipsoidea were significantly higher in blue LED growth conditions compared to white, green, and red LEDs. C. ellipsoidea cells were 3˗7.04 μm in size and the maximum area of the cell was 38.94 μm² in blue LED treatment. Results of this study demonstrated that blue LED light spectra was the most suitable condition to induce nutritionally rich biomass production of C. ellipsoidea, which can be used as a potential source of fish feed towards sustainable aquaculture.

Journal to Publish Research Papers in the field of Environment, Agriculture and Biotechnology. It is DOI peer reviewed online journal.

The present study was conducted to reveal the present scenario, problems and the prospect of fish farming of Gazipur Sadar upazila Bangladesh. The primary data were collected through field survey, questionnaire interview and focus group discussion from the fish farmers of several villages and urban areas of the upazila. Secondary data were collected from the Department of Fisheries and aquaculture extension section. Gazipur Sadar upazila has 14462.42 ha potential fisheries resources of which floodplains, seasonal water bodies, and ponds comprise 71.01%, 13.04%, and 8.57%, respectively. The total fish production of the upazila in 2016-17 was 14492.7 MT, 27% of the Gazipur district. The highest fish production of 5436 MT and 4.39 MT/ha/year came from the pond sector. Among different pond culture systems, the semi-intensive system had the highest fish production output (2826 MT). Exotic carps were the highest produced fish in the ponds. However, in spite of comprising a huge proportion of seasonal floodplains the fish production from this sector was only 0.42 MT/ha/year in 2016-2017. This indicates the poor utilization of inland open water resources for fish production in the study area. The major areas were identified to improve the existing pond fish farming situation were access to low-interest loan, quality seed, supply of advanced technologies, need-based training, and marketing facilities. Along with improving the pond fish farming, community-based fisheries management and some aquaculture initiatives on private own seasonal floodplains should be taken on a priority basis to improve open water management and to flourish inland fish production in the study area.Progressive Agriculture 29 (1): 53-63, 2018

Marine resources of Bangladesh are abundant, both in terms of huge sea area and its biological richness. The marine water area supports a large number of commercially important fin fish, mollusks, crustaceans, and seaweeds, offering significant economic potential due to their diversified use and high demand in the international market. Therefore, the current review comprehensively examines both the contribution and potentials of marine fisheries resources to the economy, as well as the challenges involved in marine fisheries sectors in attaining a sustainable blue economy in Bangladesh. The study revealed that, the marine fisheries plays an important role in national economy and has huge prospect in employment generation and ensuring food security of Bangladesh. The expansion of mariculture and effective utilization of marine resources will open a new window for the economic development of Bangladesh. Marine fisheries production of Bangladesh has increased over the last two decades, but its relative share in total fisheries production has declined. Despite being rich in marine living resources, commercial mariculture has been developed only for shrimp, prawn, and mud crab. Challenges hindering mariculture expansion includes limited research, technological deficiencies, inadequate skilled workforce, underdeveloped domestic seafood markets, and financial constraints. Concerted efforts including exploring new fishing grounds, conducting stock assessments, implementing scientific management strategies, enacting a national marine fisheries policy, enforcing legislation, and establishing robust surveillance and monitoring mechanisms are required to foster a sustainable blue economy in Bangladesh.

Climate change-induced sea-level rise, salinity intrusion, sudden water surge, natural calamities, etc. affect the fish biodiversity, food security, and coastal livelihoods that highlight the necessities of developing climate-resilient strategies e.g. adaptive aquaculture techniques. Cage culture of salinity-tolerant fish may be an adaptation strategy to compensate for the losses of freshwater fish production by climate change in coastal areas. Therefore, a 120-day long field experiment was conducted to evaluate the cage culture potentiality of Mystus gulio in the coastal region of Bangladesh. Three treatments at the stocking density of 90 (T₁), 135 (T₂), and 180 (T₃)/m² were stocked in nine cages (1.115 m²). Significantly (p<0.05) higher growth performance and feed utilization were recorded in T₁ followed by T₂ and T₃. In return, considering overall growth, survival, production, coast-benefit analysis, T₂ was found more profitable followed by T₃ and T₁. This result revealed that the culture of M. gulio in floating net cages might be a potential climate-adaptive aquaculture technique in the coastal region. However, further research works are necessary for optimizing stocking density, nutrition, social acceptance, etc. before conclude it as a viable climate-resilient adaptive aquaculture practice.

A natural product such as chitosan promotes health benefits and extends the shelf life of the processed products. Chitosan has been used as a food additive due to its antioxidant and antimicrobial activities. This study was conducted to optimize the chitosan concentration as a coating agent on the quality and shelf life of Labeo rohita fillets during frozen storage. Chitosan (CH) solutions were prepared with 0.5 %, 1 %, and 2 % (w/v) CH in 1 % (v/v) glacial acetic acid for coating application. The control (0% CH) and CH treated fish fillets were stored at -18 °C for 14 weeks and assessed for chemical (pH, thiobarbituric acid reactive substances (TBARS), total volatile basic nitrogen (TVB-N), and K-value), microbiological (aerobic plate count (APC)), and sensory properties. The pH, TBARS, and K-value of 1 % and 2 % CH treated fish fillets were acceptable up to 14th week of storage, while TVB-N value was permissible up to 12th week of storage. After 14th week of storage, the APC of control, 0.5 %, 1 %, and 2 % CH treated fillets were 7.18 log CFU/g, 5.02 log CFU/g, 4.13 log CFU/g, and 3.21 log CFU/g, respectively. The fish fillets treated with 1 % and 2 % CH had acceptable sensory attributes up to 12th week, while control fillets were unacceptable after the 6th week of storage. This study demonstrated that 1% CH could be used as a natural additive for keeping the quality and extending the shelf life of L. rohita fillets during frozen storage.