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The search for suitable fish meal replacements in aqua-diets is a salient agenda in the constant effort of making aquaculture practices more sustainable. In this study, we tested four customised diets composed by systematic inclusion of pre-selected fish meal substitutes, lupin kernel meal, BSF meal, TH and PBM on growth, metabolism, cytokine profile, gut morphology and microbiota of juvenile Lates calcarifer. Five isoproteic and isoenergetic diets were prepared viz. FM100 as a control (without fish meal substitute), while FM75, FM50, FM25 and FM0 indicates replacement of fish meal (FM) at 25%, 50%, 75%, and 100%, respectively by a mixture of four different pre-selected non-fish meal (NFM) ingredients. Fish fed FM100, FM75, FM50, FM25 exhibited consistent growth and haematological response, while the fish fed no fishmeal (FM0) showed significant decline in final body weight (FBW) and specific growth rate (SGR). The poor growth performance was correlated with a decrease in villous width, microvilli height and goblet cells density. A significant shift in abundance profile of Psychrobacter in the gut microbial profile of fish fed FM50 was noticed compared to fish fed FM100. The results of qRT-PCR showed up-regulated expression of innate immune responsive genes in the FM50 group. The adverse impacts on growth performance and gut health of fish fed FM0 suggest that the complete substitution of fishmeal is not advisable and the inclusion range of these alternatives should be decided for a species only after examining their effect on maximal physiological performance.

AIMS: This study conducted bacterial community, virulence and antibiogram profiling inside the hindgut and skin of freshly caught hilsa fish and those sold at markets. METHODS AND RESULTS: The results of 16S rRNA‐based high‐throughput sequencing showed a higher number of bacterial genera in marketed fish samples than in fresh fish samples. The total operational taxonomic units, genus counts and diversity index were significantly higher (P > 0·05) in marketed fish, which also had abundant pathogenic bacterial groups. Skin samples had a lower profusion of pathogenic bacteria than gut samples. A total of 52 bacterial isolates from nine species were identified in this study, of which 25 were from a Chittagong market and 22 were from a Dhaka market, whereas only five were from fresh hilsa. The polymerase chain reaction amplification of 12 species‐specific virulence genes in the 52 isolates, namely, aer, hly, chxA, toxB, rtxC, sfa, uge, norB, trx, toxA, ipaH, sigA and coa, indicated a high number of positive samples containing Vibrio cholerae, Aeromonas spp., Klebsiella pneumoniae, Escherichia coli and Staphylococcus aureus. Antibiogram profiling of these bacteria against 10 commercial antibiotics showed high‐resistance patterns of the isolates against sulfamethoxazole, kanamycin, neomycin, ampicillin and tetracycline. CONCLUSION: The results reveal the spread of multidrug‐resistant bacteria in hilsa fish marketed for human consumption in Bangladesh. SIGNIFICANCE AND IMPACT OF THE STUDY: This study highlights the risk of spreading environmentally and clinically pathogenic bacteria in fish sold for human consumption in Bangladesh. Such bacteria come from aquatic pollution and poor handling, storage and transportation practices that may predispose fish to major outbreaks of infectious and waterborne diseases.

Peanut (Arachis hypogaea) is mainly grown for oil extraction and the remaining oil-free seed referred as peanut meal (PM) leaves with high protein content which can be a possible substitute for fishmeal in aqua-diets. This study evaluates the suitability of three types of processed peanut seeds, namely untreated PM (UPM), fermented PM (FPM), and germinated PM (GPM) from peanut seeds to replace fishmeal in barramundi (Lates calcarifer) diets cultured under a commercial production environment. Nine formulated diets having 3 inclusion levels from the 3 different peanuts (15%, 30% and 60% fishmeal replacement) were evaluated against a control without PM. The performance of various types and levels of PMs was assessed by examining the growth, gut and liver condition and survival of fish after eight weeks of feeding the test diets. The immunological responses of juvenile barramundi were assessed by exposing the fish to the hypoxic conditions for 4 hours. The results showed that fermentation and germination significantly (P

Current study reports the length‐weight relationships (LWRs) of three marine fish species collected from the fishermen catches covering three seasons i.e., rainy, autumn and winter between June, 2016 and February, 2017. Fishermen caught the species using beach seine net (3.5 cm mesh size) and set bag net (0.5 cm mesh size) up to 200 m far away from the shoreline. The LWRs for fish species were W = 0.0180TL³.¹⁹² for A. longispinnis, W = 0.0109TL².⁹⁷¹ for R. russeliana and W = 0.0098TL².⁹⁴² for C. neglecta with their r² values of 0.971, 0.962 and 0.997, respectively.

The present study investigates if the total replacement of dietary fishmeal (FM) with poultry by-product meal (PBM), supplemented with methionine influences the muscle fatty acids composition, normal gut morphology, histological traits of the liver, muscle, and gill, liver enzymes, immune and antioxidant response, and stress-related gene in juvenile barramundi, Lates calcarifer in relation to growth and feed utilization. Barramundi (3.58±0.01g) were randomly distributed into six 300 L seawater recirculating tanks (25 fish/tank) and fed two formulated isonitrogenous and isolipidic diets for 6 weeks. The control diet had FM as the sole animal protein source, whereas other test diet had only PBM as an animal protein source. Dietary PBM affected the fish performance and feed utilization. Regarding muscle fatty acid profile, total saturated fatty acids and monounsaturated fatty acids elevated while total PUFA particularly n-3 LC-PUFA and EPA decreased in PBM fed fish than control diet fed fish. Liver, muscle, gill, and intestinal histology showed no obvious alteration in control diet fed fish, however, more lipid droplets and hepatic vacuolization in the liver, necrotic myotome in muscle, hyperplasia in secondary lamellae in gill and short and broken folds in the intestine were observed in PBM fed fish. Similar to light microscopy observation of intestinal morphology, the transmission electron microscopy (TEM) analysis revealed shorter and smaller microvilli in fish fed PBM. Histopathological alterations in the liver of PBM fed fish were further associated with the elevated levels of aspartate aminotransferase (AST) and glutamate dehydrogenase (GLDH) and the significant upregulation of stress-related genes, HSP70 and HSP90. Also, a negative influence on lysozyme activity, and antioxidant enzymatic activities were recorded in fish fed PBM. Overall, it can be concluded that a total substitution of FM protein by methionine supplemented PBM negatively influenced the growth performance, liver health, histological traits of different organs, immune and antioxidant response, and expression of stress-related genes in juvenile barramundi.

This study aimed to characterize the bacterial communities in rearing water treated with commercial plastic biological ball filters named as Bio-ball in marron culture for 60 days. Inclusion of Bio-ball in the aquaculture tanks showed improvement in water quality parameters and enrichment of bacterial communities in terms of operational taxonomic units. The water treated with Bio-ball showed significantly less nitrate, nitrite, ammonia, phosphorus and high dissolved oxygen concentration than untreated control group. At phylum level, Proteobacteria was dominant in both control and treated water, whereas Firmicutes was found to be significantly (P < 0·05) enriched in Bio-ball treated water. Among the classified genus, Aquabacterium and Polunucleobacter were most dominant in control and Bio-ball treated water respectively. Linear Discriminant Analysis Effect Size exhibited 31 indicator bacterial genus, 10 in control and 21 in treated condition, suggesting the enrichment of microbial lineages with addition of Bio-ball. The bacteria Haliscomenobacter, Hypnocyclicus, Pajaroellobacter and Vibrio were found to be significantly (P < 0·001) correlated with higher pH, nitrate, nitrite, phosphorus and ammonia in control tanks, whereas Corynebacterium was linked to higher temperature in treated water. Overall results suggest that Bio-ball filter media significantly improved the water quality and microbial populations in aquaculture tanks. SIGNIFICANCE AND IMPACT OF THE STUDY: The results of this study revealed the positive impacts of Bio-ball in enrichment of microbial flora associated with the degradation process of nitrogenous and organic compounds. Bio-ball also showed the capability to prevent the colonization of harmful bacteria, and favoured the growth of beneficial microbes in aquatic system. This study therefore could pave the ways of increasing the aquaculture production by improving the water quality.

To elucidate genetic differentiation in three river populations (Tentulia, Paira and Kirtonkhola) of Polynemus paradiseus, ten enzymes encoded by seventeen presumptive loci were screened using allozyme electrophoresis marker, where five were polymorphic (Est-1*, Gpi-1*, Gpi-2*, G3pdh-2* and Mdh-1*). The mean proportions of polymorphic loci were observed 17.65, 29.41 and 11.76% in Tentulia, Paira and Kirtonkhola populations, respectively. The highest mean number of allele per locus and mean proportion of heterozygous loci per individual were observed in the Paira population (1.294 and 16.667%, respectively). The highest observed heterozygosity (H ) and average expected heterozygosity (H ) were 0.078 and oe 0.050, respectively found in Tentulia population. The highest pair-wise population differentiation (F =0.148) ST and lowest gene flow (N =1.443) were found in Tentulia-Kirtonkhola indicate the close relationship among them. m The pair-group method with arithmetic mean dendrogram of Nei's genetic distances showed that the three river populations of P. paradiseus constructed two clusters. Paira and Kirtonkhola populations made one cluster (D=0.001) and separated from Tentulia population by the genetic distance of 0.014. The results suggested that the considerable genetic variation is maintained among the natural P. paradiseus populations.

Summary This study presents the first report of length–weight relationships (LWRs) for Apocryptes bato (Hamilton, 1822), Salmophasia phulo (Hamilton, 1822), and Silonia silondia (Hamilton, 1822), excluding Anodontostoma chacunda (Hamilton, 1822), from fishermen's catches landed in a coastal artisanal fishery at Patuakhali, Southern Bangladesh. Specimens were sampled occasionally over a period of 1 year between August 2014 and September 2015. Fishes were collected from coastal fishermen using cast nets (mesh size

The present ichthyological report describes the length‐weight relationships (LWRs) of three catfish species (Eutropiichthys murius, Nangra nangra and Gagata viridescens) belonging to two families from the Kaliganga River, a tributary of the Dhaleshwari River, Bangladesh. The analyses included 306 specimens collected monthly from fishermen's catches during October 2015 to April 2016. Ranges of regression parameters a and b of the three species were within 0.0058–0.0099 and 2.900–3.142, respectively with highly correlated coefficients of determination (r² > .995; p

Populations of gizzard shad, Anodontostoma chacunda from four adjoining rivers (Karnafuli, Feni, Bhulua, and Moheskhali) of the Bay of Bengal, Bangladesh, were studied to investigate phenotypic structure on the basis of body shape morphometrics using a truss network model. A total of 28 distance variables were extracted by interconnecting 12 morphometric landmarks. The transformed morphometric measurements were subjected to discriminate function analysis (DFA), principal component analysis (PCA), cluster analysis (CA) and univariate analysis of variance (ANOVA). Based on the analysis of variance, all morphometric measurements differed significantly (P

Morphological parameters comprising length-weight relationships (LWRs), sex ratio, condition factor (KF) and allometric growth of paradise threadfin, Polynemus paradiseus from the southern coast of Bangladesh were estimated. A total of 221 specimens were collected with the help of local fishermen ranging size 8.30-13.70 cm standard length (SL) and 11.64-50.67 g body weight (BW) during the period of January to October, 2104. The overall sex ratio of the samples did not reveal significant variation from the expected value of 1:1 (male: female=1:0.99, χ2=0.004, P < 0.05). Length-frequency distribution revealed a size predominance of males over females, where mean variation of males consistently exceeded that of females throughout the year. The allometric coefficient b of LWR significantly deviated from 3 indicating allometric growth in males and females. The analysis of covariance (ANCOVA) showed significant differences in slope and intercept between the sexes (P < 0.001). KF by month in both sexes indicating the fishes were thriving very well in the coast of Bangladesh. This study reports the first findings regarding the LWRs, sex ratio and KF of Polynemus paradiseus in the coastal waters of Bangladesh

Barramundi, Lates calcarifer (Bloch, 1790) is one of the most commercially important species world-wide, with aquaculture of this species being relatively new in Bangladesh. This paper outlines the on growing farming systems of barramundi, its cultural constraints, economic significance, and availability in coastal Bangladesh. Although the farming practice of this species is relatively new, it is gaining prime preference among the consumers due to its nutritive values, taste and high flesh content compared to other commercially important species available in the entire coastal area. Farmers are following semi-intensive and extensive farming system along with other species due to the lack of seed in Bangladesh except some ordinary nurseries which rear natural sources fertilized eggs and fry to fingerling size. Overall, a shift from large scale capture fishery to culture across the southwestern part of Bangladesh marks an important emerging trend of barramundi farming in this area.

The study was carried out to investigate the stock identification of the olive barb, Puntius sarana (Hamilton, 1822) through morphometric characters. A total of 110 sample ranging from 10.00-16.80 cm in total length (LT) and 13.94-63.46 g in body weight (BW) were examined to assess the morphometric variation of Puntius sarana from four mighty rivers; the Padma, Meghna, Jamuna and the Halda in Bangladesh. The univariate result showed significantly variation (p

Small indigenous fish species (SIS) play a vital role in providing animal protein sources for human. The Gorai river, a Ganges tributary is a habitat of considerable number of SIS. A total of 11040 individual from 40 species were collected belonging 7 orders and 19 families using 5 fishing nets and 1 fish trap of which 2 species were critically endangered, 7 endangered, 7 species vulnerable, 18 species not threatened, 2 data deficient and 4 species were not in evaluated category. Dominant orders were Cypriniformes and Perciformes each contained 12 species, dominant family was Cyprinidae (11 species) and most dominant species was Chela cachius (2253 individuals). Diversity indices ranges from Simpson’s dominance index (0.06-0.09), Simpson’s index (0.91-0.94), Shannon Weiner index (3.08-3.24), Evenness (0.56-0.66), Menhinick’s index (0.61-0.67), Margalef’s index (4.48-4.77), Equitability (0.84-0.89) and Fisher alpha (5.86-6.31), respectively. Highest numbers (38) of SIS were caught by set bag net. Maximum total length 4.6 cm of Corica soborna was the new record. Considering the nutritional importance and reducing number of SIS inhabiting in the river Gorai, the present study aimed at documentation of SIS, their threatened status and conservation of SIS through laws and regulations.

This study was conducted to delineate the stock structure of Sillaginopsis paniijus based on morphometric characters of the species. A total of 194 specimens were collected from the Meghna, Tentulia and Baleswar rivers located in the southern coastal zone of Bangladesh. Data were subjected to univariate ANOVA, multivariate ANOVA, discriminate function analysis (DFA), and principal component analysis. Mean variations of ten morphometric characters; HD, HBD, LBD, PsOL, ED, SnL, SPrDL, HAF, LSDB and LPB showed significant differences (p