Search

The study was carried out in Matiranga Upazila, Bandarban district, which is considered one of Bangladesh's major hill tract regions. The study aimed to identify present farming conditions, prospects, and problems and suitable solutions to the problems of fish farming. Different participatory rapid appraisal tools such as focus group discussion, field visits, and farmers' interviews were used to collect relevant fish farming information in the study area. The polyculture method was the most practised aquaculture method. Among the selected farms, eleven fish species were identified as culture species. The transportation cost for seeds purchased from remote areas was high (11% of total seed cost). The average transportation-related mortality of fish fry and fingerlings was 7.2% and 2.8%. Feed cost was found as the major cost (58.4%) in aquaculture. Costs and revenue for fish production per decimal varied from BDT 311 to 3528 and BDT 23 to 1268. Utilization of vacant lake, youth and women engagement, integrated aquaculture, the desire of people to engage in aquaculture, and available human resources were found as significant prospects. The major problems identified were lack of hatchery, high feed cost, lack of stakeholder linkage, lack of capital for fish farming, and lack of proper knowledge, guidelines, and consultancy for fish culture. A community-based aquaculture model was proposed to overcome the present challenges and problems in the study area. The model may help to expand aquaculture and thus improve the livelihood and socio-economic status of the people of the hilly areas of Bangladesh.

The distribution of fish larvae in estuaries is crucial for comprehending the functioning of these ecosystems and their role as nursery grounds for marine fish species. Data regarding larval fish assemblages in the coastal waters of Bangladesh are currently scarce. This study examines the spatial and seasonal dynamics of larval fish communities in these waters using a two-year sampling effort with a bongo net. This study investigates the diversity, abundance, and distribution of larval fishes at four sites (Bakkhali River Estuary, Moheshkhalipara, Naf River Estuary, and Rezu Khal Estuary) on the southeastern coast of Bangladesh. A total of 10,387 fish larvae representing 25 families were identified. Clupeidae (42.9%), Engraulidae (35.5%), Ambassidae (10.1%), Myctophidae (2.1%), and Gobiidae (1.9%) were the five most dominant families based on the larval catch composition. Marked seasonal differences in the larval fish abundance were observed. However, these differences were not observed when comparing the four sampled sites. Additionally, the correlation between environmental variables and the larval abundance indicated that salinity negatively influences (p < 0.001) the larval fish abundance. This is the first comprehensive investigation of larval fish assemblages in the coastal waters of Bangladesh. The findings of this study enhance our understanding of the nursery habitat requirements for the early development stages of both migratory and resident species in subtropical coastal waters, providing valuable information for potential applications in management and conservation efforts.

Microplastic (MP) pollution in aquatic environments is a growing concern worldwide. This study investigated the abundance, types, and attributes of MPs in the surface water at two industrial sites (Avoimitro Ghat and Kalurghat) along the Karnaphuli River in Chattogram, Bangladesh. Sampling was conducted over eight months across three transects encompassing a total area of 500 m at each site. A manta net of 200 μm mesh size was used to sample MPs. The obtained samples were subsequently filtered, enumerated, and characterized using a stereo microscope and imaging software. The mean abundance of MP particles (per km2) was found higher in Avoimitro Ghat (94,861 ± 57,126) than in Kalurghat (31,343 ± 23,183). A significant statistical difference (p < 0.05) was observed in the mean abundance of MP particles between the wet and dry seasons. The fragment group of MP exhibited the most abundant category, whereas the pellet category displayed the lowest. MPs with an elongated shape prevailed at both locations throughout all seasons. At Avoimitro Ghat, blue-colored MPs demonstrated the highest mean count, while in Kalurghat, the highest mean count belonged to brown-colored MPs. The size distribution of MPs differed between the two sites, with 1–2 mm MPs being plentiful in both seasons and Avoimitro Ghat, whereas MPs ranging from 500 µm to less than 1 mm were abundant in Kalurghat. Ten (10) polymer types were found from Fourier-transform infrared spectroscopy (FTIR) analysis with high levels of polypropylene atactic in both Avoimitro Ghat (32%) and Kalurghat (17%). The findings provide important insights into MP pollution in the Karnaphuli River, which may aid in developing effective strategies to mitigate the impacts of MP pollution on the aquatic ecosystem and human health.

Suckermouth armoured catfish of the genus Pterygoplichthys (Siluriformes: Loricariidae) are significant threats to aquatic biodiversity, ecosystems, habitats, and fishery production in different countries. Their unique characteristics and adaptive features help their successful invasion. These fish harm fish habitats, compete for food and space, prey on fish eggs, and displace the native fish populations. They erode river banks, alter benthic ecology, make holes in the river bank, and remove aquatic plants. Elimination, control, and intrusion prevention are possible management strategies. Utilising them as food and preparing value-added products and byproducts using them are viable ways to reduce their number. Management is challenging, owing to their tolerance and excellent adaptability. With severe dangers to Bangladesh's fisheries industry and aquatic environment, suckermouth armoured catfish have invaded natural waterbodies and aquaculture ponds. There is a lack of accurate information on invasion status, types of invading species, and potential dangers of invasion to create a management framework in Bangladesh. Therefore, this review introduces the key characteristics, habitats, invasion impacts, and management and utilisation aspects of suckermouth armoured catfish in different countries. The review may help in understanding how they affect native fish, aquatic organisms, habitats, and the aquatic environment globally. Finally, what kind of threats they may pose and how they can be managed sustainably in Bangladesh.

Ocean acidification is caused mainly by atmospheric carbon dioxide stored in the ocean. Ocean acidification is considered a major threat to aquatic life, and how it influences the abundance of marine fish larvae is still unclear. This research was designed to measure the current ocean acidification scenario of the Cox's Bazar coast of the Bay of Bengal, Bangladesh, and its probable influence on the abundance of fish larvae. Three research stations were selected: Bakkhali river estuary, Naf river estuary, and Rezu Khal. Monthly sampling was done, and larvae sample was collected from the surface water column (depth: 0.5 m) using a bongo net. Water parameters such as temperature, salinity, total alkalinity, and pH were determined using laboratory protocol. The seacarb package of the R programming language was used to determine ocean acidification factors. The Bakkhali river estuary showed the highest partial carbon dioxide (143.99 ± 102.27 μatm) and the lowest pH (8.27 ± 0.21). A total of 19 larvae families were identified, and the highest larval count was found in Rezu Khal (390 larvae/1000 m3), while the lowest was found in the Bakkhali river (3 larvae/1000 m3). Clupeidae, Myctophidae, and Engraulidae comprised more than 50% of the identified larvae. Blenniidae, Carangidae, Clupeidae, Engraulidae, and Gobiidae were found in all three seasons. Most of the larvae families showed the highest mean abundance under less pCO2. A negative correlation was observed between larvae and acidification factors such as pCO2, HCO3−, and dissolved inorganic carbon (DIC). The study revealed that acidification parameters of the Cox's Bazar coast were not in an acute state for the aquatic organisms' survival, but fish larvae abundance could be declined with raises in the partial carbon dioxide. The results of this study may aid in developing a management plan for conserving Bangladesh's marine and coastal fish.

The effects of natural plant-derived carotenoid sources on body coloration and growth performance of Sword-Tail Fish (Xiphophorus helleri) were investigated using four different dietary treatments; Commercial Feed (CF), China Rose Flower (CRF), Marigold Flower (MFF), and Carrot (CAF). CF was used as the control treatment without a natural source of carotenoids. The sources were mixed with feed (15 g/100 g) during the diet preparation. Fish were fed with four treatments twice a day for eight weeks, and then sampling was done weekly. A total of 96 fish were used for the experiment, and the mean initial weights were 3.314 g. MFF-treated fishes showed better growth performance in terms of mean weight, length and Specific Growth Rate (SGR), and carotenoid gain than the other treatments. The lowest Food Conversion Ratio (FCR) was also observed in the MFF-treated fish. The study suggested that marigold flower mixed feed could increase the body coloration and boost the growth performance of sword-tail fish and may be manufactured.