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The present study reports on biometric indices comprising length-weight relationships (LWRs) of five miniature freshwater fish species from the Kaptai Lake, the largest lake in the People's Republic of Bangladesh. The study area included 3 stations in the 11,122 km2 catchment area of the lake and each station was sampled from November 2017 to April 2018 using push net (mesh size 2 mm) for capturing the species. The values of growth coefficient b of the LWRs (W = aTLb) of the species Oryzias dancena, Oryzias melastigma, Gobiopterus chuno, Brachygobius nunus and Badis chittagongis were 2.9575, 3.1467, 3.0535, 3.058 and 2.9396 with above 0.95 coefficient of correlation (r2). These results represent the first study of LWRs for these fish species which may help in management and conservation of the species in the whole country, including its geographical distribution.

Feeding freshwater crayfish species with different diets not only affects the water quality but also induces the abundance of various microbial communities in their digestive tracts. In this context, very limited research has been undertaken to understand the impacts of various protein incorporated aqua-diets on the characteristics of water and its microbial communities. In this study, we have critically analysed the water quality parameters including pH, dissolved oxygen, nitrate, nitrite, ammonia and phosphorus, as well as bacterial communities under marron (Cherax cainii) aquaculture, fed fishmeal (FM) and poultry by-product meal (PBM)-based diets for 60 days. The results unveiled that over the time, feeding has significant impacts on organic waste accumulation, especially ammonia, nitrate, nitrite and phosphate, while no effects were observed on pH and dissolved oxygen. Analysis of 16S rRNA sequence data of water sample indicated significant (P

The composition and ichthyofaunal diversity of the Bay of Bengal and its adjacent coast have been being explored with time. Australian sawcheek scorpionfish, Brachypterois curvispina is a newly reported species in Bangladeshi water recorded from the St. Martin Island (coral reef) off the Bay of Bengal coast. The identity of this species was confirmed by comparing it with the published morphological description of a specimen reported from the Australian coast. The presence of posteriorly directed lachrymal spines is the key character of this species. Its preferred food items were observed small fish, shrimp, lobster, crab, and some aquatic insects. The dispersal of this species in this geographical area illustrates a considerable expansion of its distributional range, the previously reported Australian coast which is far off from the present record. Although the actual cause of dispersal is unexplored, climate change and global warming are assumed to stretch out the species distribution range. This discovery of Brachypterois curvispina provides a new non-native species record in the coral reef of Bangladesh and represents the northern-most dispersal in the Indo-Pacific region.

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.

In intensive farming systems, fish are held at high densities, which may increase stress, leading to susceptibility to diseases that result in economic losses. Therefore, effective feeding practices incorporating health‐promoting compounds such as proteins, hydrolysates and bioactive peptides that can stimulate the defence mechanisms of fish and achieve better growth are some of the priorities for sustainable aquaculture development. Globally, the fish processing industries generate and discard a large volume of waste every year, estimated at up to 60% of the harvested biomass. This waste can be converted to value‐added products such as fish protein hydrolysate (FPH) with the addition of various proteolytic enzymes. FPH from fish processing waste including skin, heads, muscle, viscera, liver and bones is a good source of protein, amino acids, peptides and antioxidants and has been found to possess desirable functional and bioactive peptides. A moderate inclusion of FPH in aquafeeds has the potential to improve growth, feed utilization, immune functions and disease resistance of fish. Production of FPH, targeted to more precise molecular weight ranges, has superior functionalities that are in high demand. With interest in FPH as an aquafeed supplement, this review aimed to summarize the source, production processes and functional properties of FPH and the reported impact of FPH in aquafeed supplement on fish growth, survival, feed utilization, immune response and disease resistance. Possible limitations of using FPH and future research potential as an opportunity for the use of processing fish waste are also discussed.

This study aimed to investigate the combined effects of two most potent probiotic bacteria Lactobacillus acidophilus and Lactobacillus plantarum on overall health and immune status of freshwater crayfish, marron under laboratory conditions. A total of 36 marron were distributed into six different tanks and two different feeding groups, control and probiotic-fed group. After acclimation, control group was fed with basal diet while probiotic group was fed 109 CFU/mL per kg of bacterial supplemented feed for 60 days. The results showed no significant differences in weight gain, however, probiotic feed significantly enhanced some hemolymph parameters and biochemical composition of tail muscle. Histology data revealed better hepatopancreas health and higher microvilli counts in the marron gut fed probiotic diet. The probiotic bacteria triggered significant shift of microbial communities at different taxa level, mostly those reported as beneficial for crayfish. The probiotic diet also enriched the metabolic functions and genes associated with innate immune response of crayfish. Further correlation analysis revealed significant association of some taxa with increased activity for hemolymph and immune genes. Therefore, dietary Lactobacillus supplementation can modulate the overall health and immunity as well as gut microbial composition and interaction network between gut microbiota and immune system in crayfish.

Length‐weight relationships (LWRs) were estimated for seven small indigenous cyprinid fish species including Securicula gora, Osteobrama cotio, Esomus lineatus, Pethia gelius, Megarasbora elonga, Gonialosa manmina and Glossogobius aureus occurring in the Kaptai Lake, Bangladesh. Fish were collected monthly basis between March and October, 2018 from fishermen catches landed in the fish landing center, Rangamati. Fishermen operated lift net (mesh size

The present study investigated the supplemental effects of tuna hydrolysate (TH) in poultry by-product meal (PBM) and dietary fishmeal (FM) diets on antioxidant enzymatic activities, gut microbial communities and expression of cytokine genes in the distal intestine of juvenile barramundi, Lates calcarifer. Fish were fed with fermented (FPBM + TH) as well as non-fermented PBM (PBM + TH) and FM (FMBD + TH) diets with 10% TH supplementation for 10 weeks. A basal diet prepared without TH supplementation served as control. The results showed that the activity of glutathione peroxidase was significantly higher in FPBM + TH than the control, while the malondialdehyde and catalase activities were unchanged. FPBM + TH diet significantly (P 0.05) upregulated the pro-inflammatory cytokines including IL-1β and TNF-α while considerable downregulation (P 0.05) was observed in the mRNA expression levels of anti-inflammatory cytokine, IL-10 in the distal intestine of fish. The 16SrRNA analysis using V3-V4 region evidenced the ability of FPBM + TH to modulate the distal intestinal gut microbiome, augmenting the richness of Firmicutes and Fusobacteriaat at phylum level and Bacillus, Lactococcus and Cetobacterium at genus level. All these results have shown that fermented PBM with TH supplementation could improve the antioxidant capacity and inflammatory responses of juvenile barramundi while influencing the microbial communities at both phylum and genera levels.

The effects of tuna viscera hydrolysate (TVH) on juvenile pompano Trachinotus blochii, growth performance, nutritional response, intestinal and liver health, and resistance to Streptococcus iniae were investigated in this study. Five isonitrogenous and isocaloric diets (protein 46.0%, lipid 10.0%) were formulated in which TVH was added to replace fishmeal protein at levels of 0 (control), 30, 60, 90, and 120 g kg-1, labelled as TVH0, TVH05, TVH10, TVH15, and TVH20, respectively. Triplicate groups of pompano were fed the respective diets for ten weeks. The results showed that fish fed diets containing TVH10 produced significantly higher final body weight and specific growth rate in comparison to the fishmeal control ( P < 0.05 ). Dietary TVH did not produce any effect on feed utilisation, somatic indices, and proximate composition of juvenile pompano ( P > 0.05 ). While most amino acids were unchanged by the dietary inclusion of TVH, phenylalanine and valine levels were significantly lower in the fish fed TVH20 diet compared to the control. Fish fed the TVH20 diet had significantly lowered total serum protein compared to the TVH10 treatment, whereas other biochemical parameters in the blood did not show any difference among treatments. The intestinal histology indicated a significant increase in goblet cell numbers in fish fed TVH10 diet. Fish fed diet supplemented with TVH showed the highest disease resistance against Streptococcus iniae after 14 days of challenge. Based on a quadratic regression between final body weight and dietary TVH levels, the optimum TVH was calculated to be 10% or 60.0 g kg-1 for maximum growth performance when fed to pompano.

To observe phenotypic differentiation among populations of Silond catfish

Six experimental diets were prepared in a 3 × 2 experimental design involving three inclusion levels (0%, 50%, and 100%) of poultry by-product meal (PB) and two concentrations (0 and 60 mg/kg) of tuna hydrolysates (TH), labelled as PB0, PB0TH, PB50, PB50TH, PB100, and PB100TH, respectively. The diets were fed to juvenile pompano for 10 weeks to investigate the nutritional value of PB in conjunction with TH supplementation on growth, feed efficiency, biochemical composition, haematological and histological responses in the species. The results indicated that the final body weight, specific growth rate, and feed conversion ratio were negatively affected by the increasing replacement of fishmeal by dietary poultry by-product meal with or without TH supplementation compared to the control (P

This study investigated the effects of replacement of fishmeal (FM) with poultry by-product (PBM) protein, supplemented with black soldier fly, Hermetia illucens (HI) larvae on growth, histomormhology, immunity and resistance to Vibrio harveyi in juvenile barramundi. Two hundred and twenty five barramundi averaging 3.51 ± 0.03 g were randomly allocated into three groups and fed isonitrogenous and isocalorific diets containing different levels of PBM supplemented with HI as follows: Control (FM based diet), 45PBM + HI (45% PBM supplemented with 10% HI), and 90PBM + HI (90% PBM supplemented with 10% HI) for 6 weeks. Results showed that dietary inclusion of 45PBM + HI significantly improved the growth performance than control whereas growth inhibition occurred in the 90PBM + HI. The 45PBM + HI groups demonstrated significant increases in histometric measurements (villus and enterocyte width, and microvilli height) and acidic mucins. The impaired growth in 90PBM + HI groups was further associated with multifocal necrosis in the liver, an upregulation of the stress related genes (HSP70 and HSP90) and increase in the levels of liver enzymes. When 45PBM + HI was fed, survival against V. harveyi increased significantly and also an increase in serum immunity and immune-related genes in the head kidney was observed after infection.

This study was conducted to investigate the effects that tuna hydrolysate (TH) supplementation in poultry by-product meal (PBM) diets would have on growth, immunity and resistance to Vibrio harveyi infection in juvenile barramundi, Lates calcarifer. Five isonitrogenous and isocaloric diets containing fishmeal (FM) without TH supplementation (control) and four diets with 10% TH supplementation viz. a FM protein diet (FMBD + TH), a 75% PBM protein diet (LPBM + TH) and two 90% PBM protein diets, either bioprocessed (BPBM + TH) or unprocessed (HPBM + TH), were formulated for juvenile barramundi, Lates calcarifer. The diets were fed to triplicate groups of juvenile barramundi (average pool weight 12.63 ± 0.11 g) for 10 weeks. Significantly (P 0.05) higher final body weights and specific growth rates were noted in fish fed with FMBD + TH and BPBM + TH diets when compared to the control. Transmission electron microscopy observation of fish distal intestines revealed a significant enhancement of microvilli length in fish fed FMBD + TH and BPBM + TH whereas scanning electron microscopy analysis found no significant difference in microvilli density. A bacterial challenge with Vibrio harveyi was conducted for 14 days after the growth trial to test the immune response and survival of barramundi. In the pre-challenge condition, a significant reduction in blood glucose was found in BPBM + TH compared to the control, and fish in the post-challenge at 24 h had higher glucose levels compared to fish in the pre- and post-challenge conditions at 72 h. The serum lysozyme activity was significantly higher in FMBD + TH and BPBM + TH compared to the control and fish at 72 h post-challenge exhibited higher lysozyme activity in each treatment compared to all dietary groups in the post-challenge condition at 24 h and to HPBM + TH and BPBM + TH in the pre-challenge condition. Fish fed FMBD + TH, LPBM + TH and BPBM + TH diets had significantly higher survival to the bacterial challenge than fish in the control and HPBM + TH. These results showed that PBM supplemented with TH could successfully replace FM without compromising growth, however, bioprocessed PBM supplemented with TH (BPBM + TH) may significantly improve growth performance, immune response, intestinal health and disease resistance in juvenile barramundi.

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.

A total of 160 barramundi’s (Lates calcarifer Bloch, 1790) sampled from four rivers (Tentulia, Balaswar, Bakkhali, and Andarmanik) along the southern coastal region of Bangladesh were investigated in terms of morphometric characters to reveal the intraspecific variation. Twenty-five morphometric measurements were extracted using the conventional method and subjected to multivariate analyses (i.e., principal component analysis (PCA), discriminate function analysis (DFA), cluster analysis (CA)) to distinguish individuals from different rivers. The result demonstrated that twenty-two out of 25 measurements was statistically significant (Univariate ANOVA) among all four populations. PCA analysis of morphometric characters resulted in two principal components, PC I and PCII which accounted for 79.25% and 4.28% of the total data variance. PC I-PC II plot explained 83.53% of total variance differentiated the population of L. calcarifer into two groups. Discriminate analysis correctly classified about 88.1% of the examined fish into the four areas. The UPGMA dendrogram showed that Bakkhali populations were the most morphologically different populations in comparison to other populations, while Andarmanik and Balaswar populations were very close to each other. The strong morphometric variation between Bakkhali and Tentulia, Andarmanik and Balaswar was observed in the present study, suggested the evidence of the separate stock population of barramundi in these locations, which might require distinct stock management strategies for resource sustainability in the waters of southern Bangladesh. However, if these findings are supported by further molecular markers and geometric morphometry, this would be a strong indication of different stocks of this population in the four rivers of southern Bangladesh.

Aerolysin (aer) is one of the most important and abundant virulence factors in the infection of fish by Aeromonas veronii. A comprehensive study on the molecular characterization and pathogenicity of the aer gene from 34 A. veronii isolates from diseased carp and catfish was carried out and its interactome was analysed to observe the functional correlations between aer and other proteins within the A. veronii network. The PCR-based amplification of aer from the 34 isolates of A. veronii showed more aer-positive isolates from catfish with a high pathogenic potential in the in vivo challenge test than the carp fish. The analysis of aer gene sequence from challenged fish revealed significant sequence divergence according to the types and geographical distribution of the fish. The networking analysis of aer from the model A. veronii B565 revealed histidine kinase (cheA) as the most functional interacting partner. The study of the interaction between aer from the experimental A. veronii and cheA demonstrated that the A chain of cheA plays a more important role than the corresponding B chain during contact, and a linker sequence of 15 residues controlled the entire interaction process. Therefore, cheA could be an excellent drug target for controlling A. veronii infection of fish.

A feeding trial was conducted to test the effects of partial replacement of fishmeal (FM) protein and fish oil (FO) with partially defatted black soldier fly, Hermetia illucens insect protein, and oil, respectively, on growth performance, immune response, gut and skin barrier status, and flesh quality in juvenile barramundi. Four isonitrogenous and isocaloric diets used in the study were a control diet based on FM, 30% FM replaced with H. illucens protein (HiP), 30% FO replaced with H. illucens oil (HiO), and both 30% FM and 30% FO replaced with H. illucens protein and oil (HiPO). Diets were fed twice a day to satiety in triplicated groups of barramundi with an initial body weight of 1.74 ± 0.15 g per fish. At the end of the trial, growth and feed utilization indices were found insignificant (p &gt, 0.05) between the test diets and control. A significant increase in bactericidal activity was observed in fish fed the HiP diet while serum lysozyme activity was unchanged. Stress-related heat shock proteins (HSP70 and HSP90) did not differ significantly among the test diets while immune-relevant genes (IL-1β and IL-10) were significantly upregulated in HiP and HiOP groups. The number of mucin cells were increased in the gut and skin of HiP and HiOP fed fish when compared to the control diet. The total fatty acid compositions (∑SFA, ∑MUFA, ∑PUFA, ∑n-3, and ∑n-6) in the muscles of barramundi were not significantly influenced with H. illucens protein and oil diets when compared to the control.

A 6-week feeding trial was performed to examine the effects of supplementing Hermetia illucens (HI) larvae meal when fishmeal (FM) was replaced with poultry by-product meal (PBM) in juvenile barramundi, Lates calcarifer diet. The effect was evaluated in terms of barramundi growth, filet quality, internal tissue structure, serum biochemistry, skin neutral mucins, immune response, and resistance to Vibrio harveyi. Three isonitrogenous (48% crude protein) and isolipidic (18% crude lipid) diets: an FM-based diet (control) and two diets containing 60 and 75% of PBM supplemented with 10% HI larvae (60PBM + HI and 75PBM + HI) were formulated. A total of 225 barramundi, with an average weight of 15.87 ± 0.14 g, were randomly distributed into nine tanks, each holding 25 fish. There were no significant effects of test diets on growth, but feeding HI-supplemented PBM diets significantly increased the survival rate. A significantly reduced intraperitoneal fat index in HI-supplemented-PBM-fed fish was correlated to a decreased size of peritoneal adipocytes. The observation of no histopathological alteration of the liver in the HI-supplemented-PBM-fed fish was further supported by significant alterations in serum biochemistry, in particular, a decreasing tendency of alanine transaminase, glutamate dehydrogenase, and total bilirubin. A 14-day challenge with V. harveyi indicated that HI-supplemented PBM diets reduced the infection rate in barramundi. After 24 h of infection, increased serum (lysozyme) and skin barrier functions, down-regulation of interleukin-1beta, and upregulation of interleukin-10 were found in HI-supplemented-PBM-fed fish.

Feeding freshwater crayfish species with different diets not only affects the water quality but also induces the abundance of various microbial communities in their digestive tracts. In this context, very limited research has been undertaken to understand the impacts of various protein incorporated aqua-diets on the characteristics of water and its microbial communities. In this study, we have critically analysed the water quality parameters including pH, dissolved oxygen, nitrate, nitrite, ammonia and phosphorus, as well as bacterial communities under marron (Cherax cainii) aquaculture, fed fishmeal (FM) and poultry by-product meal (PBM)-based diets for 60 days. The results unveiled that over the time, feeding has significant impacts on organic waste accumulation, especially ammonia, nitrate, nitrite and phosphate, while no effects were observed on pH and dissolved oxygen. Analysis of 16S rRNA sequence data of water sample indicated significant (P 0.05) shift of microbial abundance in post-fed FM and PBM water with the evidence of microbial transmission from the gut of marron. Post-fed marron resulted in a significant correlation of Hafnia, Enterobacter, Candidatus Bacilloplasma and Aquitella with the quality and microbial population of water. The results of this study generated valuable knowledge database of microbes-water relationship for better health management practices and production of marron aquaculture fed with FM and PBM diets in under restricted feeding regime with the feeding ratios provided.

Vibriosis caused by luminous Vibrio species is one of the biggest challenges to shrimp industry in Bangladesh. This study aimed to characterize whole microbial communities from Vibrio-infected black tiger shrimp (Penaeus monodon) using 16S rRNA-based amplicon sequencing. A total of 36 disease-free and infected shrimp were collected from six different hatcheries in Bagerhat, Bangladesh. A final pool of 12 samples (n = 6) was created by homogenization of the hepatopancreas samples from three shrimps collected from each hatchery for the same group. The amplicon sequencing data revealed significant (p < .05) decrease of alpha diversity measurements and subsequent effects (p < .05) on the hepatopancreas microbiota in the infected group, compared to control shrimp. Proteobateria and Aeromonas were the most dominant bacteria at phylum and genus level in both groups and identified as core microbiota in the community. Two bacterial groups at phyla level and eight at genus level were found associated with the alteration of hepatopancreas microbial communities and associated gene functions in vibriosis-infected shrimp, revealed by differential abundance and KEGG pathway analysis. The overwhelming abundance of Citroibacter, Shewanella and Candidatus lineages in vibriosis-infected shrimp needs further investigations.

Probiotic supplements are being used to improve the growth and immune performance of aquaculture species over the last couple of decades. In recent times, black soldier fly (BSF) is considered as one of the promising sources of alternative protein to fishmeal protein in aqua-diets. Since the freshwater crayfish, marron (Cherax cainii), a Western Australian's native and iconic freshwater crayfish species, grows fairly slow under commercial farming environment, this study was aimed to investigate the supplemental effect of BSF and BSF with probiotic bacteria Lactobacillus plantarum (BSFLP) on overall health and immune performance of marron after 56 days of feeding under laboratory conditions. The post-trial data revealed insignificant influences of any diets on growth performance, however, both BSF and BSFLP based diets significantly improved some haemolymph parameters and gut health of marron. High throughput sequence data revealed that both BSF and BSFLP diets significantly improved the diversity of microbial communities including some beneficial bacteria for crustaceans in the hindgut of marron. Further analysis showed that both BSF and BSFLP diets upregulated the expression of some genes in the gut tissue and haemocytes associated with the innate immune response of marron at 48 h post injection. The up-regulation of some immune genes in BSFLP diet group was found significantly linked to OTU abundance for Lactobacillus. The findings of this study could be helpful for improving overall health status of marron.

The Bay of Bengal coast is acting as a pristine ecological niche for many indigenous and non-indigenous fish species as along with other aquatic organisms. The present study describes the first record of lanternbelly, Acropoma argentistigma (Okamoto & Ida, 2002) from the Bay of Bengal coast, Bangladesh based on 32 specimens. The species was identified on the basis of phenotypic characteristics; for instance, pinkish red body colour, presence of U-shaped luminous gland, well-organised conical teeth on the lower jaw, 17 gill rackers, and position of anus in the middle of ventral margin. The first record of Acropoma argentistigma in the area further enhances the ichthyofaunal diversity in these area as well as overall fish species of Bangladesh.

A feeding trial was carried out to evaluate the effects of substitution of fishmeal (FM) by dietary poultry by-product meal, fermented by Lactobacillus casei and Saccharomyces cerevisiae on growth, intestinal health, microbial composition, immune related cytokines and disease resistance of freshwater crayfish, marron (Cherax cainii) against Vibrio mimicus. Two isonitrogenous and isocaloric diets were formulated by replacing FM protein with fermented poultry by-product meal (FPBM) protein at 0% (Control) and 75% (FPBM), and fed marron for 70 days. The results indicated no significant difference (P > 0.05) in final body weights between two groups of marron, whilst intestinal microvilli number per fold was increased in marron fed FPBM than the control. The 16S rRNA sequences revealed an increased number of Lactobacillus and Streptococcus, and decreased number of Aeromonas at genus level in the distal intestine of marron fed FPBM. Marron fed FPBM showed up-regulated expression of IL-8, IL-10, and IL-17F genes in the distal intestine. Significantly (P < 0.05) increased lysozyme and phagocytic activity, and higher survival was found in marron fed FPBM following a bacterial challenge with Vibrio mimicus. Therefore, it is concluded that FPBM is beneficial to marron in terms of microbial community, immune-related cytokines and disease resistance against V. mimicus.

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

The present study investigated the effect of apsozyme and betaine on growth performance, carcass composition, haemato-immunological parameters, and expression of growth hormone (GH) and insulin-like growth factor 1 (IGF1) encoding genes in beluga sturgeon (Huso huso). Fish (31.5 ± 0.5 g) were fed with different levels of multi-enzyme (i.e., 0, 250, and 500 mg) and attractant (i.e., 0.5%, 1.0%, and 1.5%). The results obtained from this study indicated that no significant difference was detected in weight gain, specific growth rate (SGR), feed conversion ratio (FCR), and growth-related genes expression with an increase in betaine in experimental treatments (P > 0.05). However, an increase in apsozyme from 250 mg to 500 mg without betaine resulted in significant elevations in weight gain, SGR, FCR, and growth-related gene expression (P 0.05). Also, the blood biochemical factors including glucose, and hepatic enzymes, i.e., alkaline phosphatase (ALP), alanine aminotransferase (ALT), and aspartate aminotransferase (AST), were not found significantly different (P > 0.05), whereas significant increases were observed in protein, albumin, and lysozyme with increased apsozyme in the diet in combined treatments (P

This study was conducted to investigate the combined effects of probiotic yeast, Saccharomyces cerevisiae, and lactic acid bacteria, Lactobacillus casei on the growth performance, biochemical response, cytokine gene expression, gut histomorphology and microbial composition of juvenile barramundi, Lates calcarifer. Barramundi juveniles with an initial mean weight of 12.17 ± 0.15 g were randomly allocated into 8 tanks (300L) at a density of 20 fish per tank and fed either a basal diet (control), or the same basal diet supplemented with 1% of S. cerevisiae and 1% of L. casei, collectively termed ‘probiotic’, for 56 days in quadruplicate. Results indicate that dietary probiotic supplementation produced significant (P

The study examined the effects of supplemental organic selenium (Se) extracted from selenoyeast on the growth performance, glutathione peroxidase (GPx) activity, biochemical status and liver histochemistry of juvenile cobia Rachycentron canadum. Six experimental diets were prepared supplemented with Se with total concentration of 1.52 (Se-1.52), 1.93 (Se-1.93), 2.29 (Se-2.29), 2.71 (Se-2.71) and 3.14 (Se-3.14) mg/kg of total Se in the diets and a fishmeal-based control diet without Se supplementation containing 1.15 (Se-1.15) mg/kg of Se was used as control. Experimental diets were fed to the fish of six treatment groups in triplicate twice daily for 8 weeks. Juvenile cobia fed dietary Se of 1.93, 2.29 and 2.71 mg/kg showed increased final body weight (FBW), specific growth rate (SGR) and feed intake (FI) than the fish fed the control diet. Se accumulations in the muscle and liver tissue displayed a positive linear relationship with dietary Se levels. Se deficiency was apparent in fish fed the control diet and displayed reduced growth and feed efficiency. Red blood cell (RBC) counts were significantly (P

The Bay of Bengal coast, Bangladesh is a hotspot of fisheries abundance and diversity. A new species of Carangid family Alepes kleinii is recorded and described for the first time in the coastal waters of Bangladesh. A total of 29 individuals of Alepes kleinii were collected from the surveyed areas between January to March, 2016. Validation of this species was confirmed by phenotypic characteristics including body and fins colour, shape, vertical stripes, number of fin rays etc. which were found to be identical to that of the Alepes kleinii described in existing literature. The regression parameter value (b = 2.81) of the length-weight relationship (W = aL b ) indicates that the Bay of Bengal provides favourable environmental conditions for the growth and development of this species. The discovery of the razorbelly scad in these waters provide valuable information regarding species distribution and extension, location and habitat preference. This information is prerequisite for the sound management of the coastal fisheries of Bangladesh.

Length–weight relationships (LWRs) were determined for three Carangid fish, [Alepes vari (Cuvier, 1833), Uraspis uraspis (Gunther, 1860) and Carangiodes oblongus (Cuvier, 1833)] inhabiting in the Bay of Bengal coast, Bangladesh. A total of 147 individuals of three species were sampled from four different sampling points of the Bay of Bengal coast, Bangladesh and examined from April 2017 to October 2017. Fishermen operated beach seine nets (mesh size BSN, 30 mm) and drift gillnet (10.5 cm) twice in each sampling campaign to catch the studied species. The calculated value for parameter “b” of LWRs were 3.003, 2.945 and 2.980 for A. vari, U.uraspis and C. oblongus, respectively.

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.

This study investigated the diversity of bacterial community in healthy and streptococcosis infected Nile tilapia (Oreochromis niloticus) to identify the primary causative agents associated with the disease using metagenomics, phylogenetic analysis and in vivo challenge test. A total of 24 fishes, both healthy and diseased were collected during summer from three different districts and six different ponds of Bangladesh. Alpha-beta diversity analysis of the next generation sequence data showed distinctly different (P

For the first time, the present study reports the life-history traits, comprising length-frequency distribution (LFD), sex ratio (SR), length-weight relationships (LWRs), condition factors (CFs), and relative growth (W R), of Clupisoma garua in the coastal waters of Bangladesh. A total of 150 specimens ranging from 8.60 to 25.20 cm total length (TL) and 4.26 to 128.80 g body weight (BW) were collected using traditional fishing gear from August 2013 to July 2014. The overall sex ratio of males to females in the study did not differ significantly from the expected value of 1:1 (χ2 =0.96, P

Soybean meal (SBM) has been commonly utilised as a substitute for fishmeal (FM) in the diets of several fish species. However, little is known regarding their effects on trace element availability and thus their importance to fish. The present study employed two feeding trials to evaluate the implications of dietary selenium (Se) on the growth, accumulation, antioxidant, and histopathological responses of juvenile barramundi (Lates calcarifer). In the first trial, each of three basal diets containing 0, 15 and 43 % SBM as replacements for 0, 25 and 75 % of FM protein on an isoproteic and isocalorific basis were either supplemented or not supplemented with 2 mg kg-1 organic Se (OS). In the second trial, the potential effect of OS supplementation in a high SBM diet was investigated in a feeding trial with five experimental diets: 75 % SBM protein as replacement of FM was supplemented with 2, 3, 4, 5 or 7 mg OS kg-1. Growth was independently influenced by the SBM level and the OS supplementation level but not by their interaction. Glutathione peroxidase (GPx) activity, haematocrit, Se accumulation and muscle tissue integrity were significantly enhanced in fish fed on OS-supplemented diets. Furthermore, when high SBM was included in diets, elevated Se tended to lower the barramundi's performance. These findings suggest that dietary supplementation of OS at 2-3 g kg-1 diet is necessary when high plant protein ingredients are incorporated in the diet, in order to maintain better growth and to afford protection against oxidative stress.