Fish In Vietnam Research Articles

CHOROLOGIC ANALYSIS OF THE MARINE COPEPODS (COPEPODA) PARASITIC ON FISHES OF VIETMAM

Nowadays 72 species of copepods (Copepoda) parasitizing marine fish in Vietnam have been identified. The chorological analysis of marine parasitic copepods allows to distinguish nine groups of species: widespread Atlantic-Pacific (23 species), Indo-West- Pacific (without Oceania) (25 species), Indo-West-Pacific with a broken range (11 species), Western Pacific (including Oceania) (1 species), Japanese-Malay (2 species), Philippine- Malay (1 species), Chinese-Australian (1 species), Chinese-Japanese (4 species) and endemics of Vietnam (4 species). The majority of Vietnamese marine copepods belong to the Indo-West- Pacific (34.7% species), and widespread Atlantic-Pacific groups (34.7% and 31.9% species, respectively). A preliminary comparison of the species composition of copepods from Japan, Taiwan, the Philippines, and Vietnam was made. Keywords: marine copepods, distribution, South

Frequent contamination of edible freshwater fish with colistin-resistant Escherichia coli harbouring the plasmid-mediated mcr-1 gene.

The threat of antimicrobial resistance is increasing. Microbial food contamination poses a serious public health risk; however, there are only a few studies on the prevalence of colistin-resistant Escherichia coli (COL-E) contamination in freshwater fish. This study aimed to characterise the antibiotic resistance genes and antibiotic susceptibility profiles of COL-E in freshwater fish in Vietnam. In total, 103 fish were collected and 63 COL-E were isolated. COL-E was investigated by genotyping mcr and AmpC/extended-spectrum β-lactamase (ESBL)-related genes. The results show that COL-E and AmpC/ESBL-producing COL-E were confirmed in 24.3% and 14.6% of the fish, respectively. Multiplex PCR for mcr-1-9 showed that all 63 COL-E harboured mcr-1, while mcr-3 was detected in 7.9% of COL-E. The minimum inhibitory concentration of colistin ranged from 2 to 256μg/mL. Meanwhile, antibiotic susceptibility results show that all COL-E were resistant to ampicillin, streptomycin, and chloramphenicol.

Spatio-temporal occurrence of different early life stages of Periophthalmus modestus in a tropical estuary

Abstract To elucidate the distribution pattern of Periophthalmus modestus, an amphibious fish, at its southernmost habitat, an investigation was conducted monthly at different locations along the Red River Delta area over two years. Spatially, planktonic larvae were caught abundantly at sampling sites along the Ba Lat Estuary and at a single site in the nearby mangroves close to the river’s main tributary. The benthic and amphibious juveniles were caught mainly in the mangroves. This finding suggests that P. modestus larvae may be transported up the river from the spawning ground by the tidal current and may use the main tributary of Ba Lat Estuary as a nursery habitat for the planktonic larval stage and expand their habitat to the mangrove along the estuary during the settling stages. Temporally, planktonic larvae occurred from February to July and peaked in May, suggesting that the main reproductive season of this fish in Vietnam is from February to July, which is earlier than in temperate areas. The abundance of larvae and juveniles of this species over time was positively correlated with water temperature. Nonmetric multidimensional scaling (NMDS) models based on size-class assemblages, months of sampling and samplings sites, together with an overlay of environmental vectors, revealed that water temperature was significantly correlated with fish size. Fish in the smaller size class tended to occur at lower temperatures, and fish in the larger size class tended to occur at higher temperatures. The distribution pattern of this species revealed in this study may partly contribute to its successful adaptation to circumstances in this tropical area.

Detection and characterization of Kudoa thunni from uncooked yellowfin tuna (Thunnus albacares) in Southeast Asia.

Myxosporean parasites Kudoa spp. have been reported in several marine fish species worldwide. However, little is known about the contamination of these parasites in raw fish in Southeast Asia, where the consumption demand of uncooked fish is increasing. In 2019, the occurrence of several cases of raw yellowfin tuna (Thunnus albacares) obtained from retail shops with the presence of unknown white, nodular cysts within the musculature have raised public health concerns for the consumption of raw marine fish in Vietnam. Microscopic examination revealed numerous myxospores with the quadratic shape of the Kudoidae. Morphologically, stained spores detected in this study are suspected to Kudoa thunni. To confirm the suspected Kudoa species, further examination of the 18S small-subunit (SSU) was conducted and the results of nucleotide sequence analysis obtained from nodular cysts revealed 99.18-100% identity to that of Kudoa thunni sequences available in GenBank. Detection of K. thunni infection in tuna in Southeast Asia highlights the need for appropriate surveillance and control measures to ensure high quality standards and safety on raw fish production and consumption.

Isolation of carbapenem-resistant Enterobacteriaceae harbouring NDM-1, 4, 5, OXA48 and KPC from river fish in Vietnam

The spread of potentially life-threatening carbapenem-resistant bacteria is a major threat to public health. This study aimed to determine the prevalence of carbapenem-resistant Enterobacteriaceae in fishery products in Vietnam. A total of 103 river fish were purchased from retail outlets and supermarkets in Vietnam. The gut contents of fish were removed, mixed with buffered peptone water, and incubated for 24 h. The bacterial broth was spread onto CHROMagar™ ECC containing meropenem. Enterobacteriaceae were selected and antibiotic susceptibility testing was performed. Bacterial identification and genotyping were performed using 16S rRNA and multiplex PCR, respectively. Our results showed that 6.8% (7/103) of river fish were contaminated with carbapenem-resistant Escherichia coli harbouring NDM-1 or -5, and 8.7% (9/103) of the samples were contaminated with carbapenem-resistant Enterobacteriaceae harbouring NDM-1, -4, and OXA-48 genes. E. coli and Citrobacter freundii harbouring the NDM-1 encoding IncA/C plasmid were isolated from one fish sample; carbapenem-resistant E. coli harbouring CTX-M-15, NDM-5, and mcr-1 were also isolated. In conclusion, bacteria isolated from fishery products were found to carry the carbapenem resistance genes NDM, OXA-48, and KPC. As carbapenem-resistant bacteria are isolated from Vietnamese fishery foods at a rate of 6.8%, it is necessary to re-consider food hygiene rules.

Classification of the multigene family of fatty acid binding proteins (FABPs) and transcription profile of the genes in striped catfish (Pangasianodon hypophthalmus)

Striped catfish (Pangasianodon hypophthalmus) is an economically important fish in Vietnam. The catfish fillets contain high fatty acid composition. The FABP family is involved in lipid transport and metabolism as well as in the regulation of gene expression and cell development. In this study, the catfish genome database was searched for fabp gene family; then, gene structure, classification and phylogenetic relationships were analyzed. In striped catfish genome, we found 10 fabp genes that are homologous to other fish species and other 5 novel fabp genes that have not been clearly annotated. These newly identified fabp genes cluster separately from the known members of the fabp family on the phylogenetic tree, and further studies are needed to understand their roles and functions. We examined transcriptional gene expression of fabp3, fabp7 and fabp10a genes in muscle, liver and brain tissues of the stripped catfish. The results showed that fabp10a gene was not strongly expressed in all 3 types of tissues; fabp3 gene was most strongly expressed in liver tissue and fabp7 was highly up-regulated in brain tissue. The results of this study provide a resource for further research on the function of fabp genes and their genetic diversity in striped catfish.

POSTHOVITELLINUM PSILOTERMINAE N. GEN., N. SP. (DIGENEA: LISSORCHIIDAE) INFECTING THE INTESTINE OF CYCLOCHEILOS ENOPLOS (CYPRINIFORMES: CYPRINIDAE) IN THE MEKONG RIVER, VIETNAM.

Herein we describe a new species and propose a new genus, Posthovitellinum psiloterminae n. gen., n. sp. (Lissorchiidae: Asymphylodorinae), based on specimens that infect the intestine of Cyclocheilos enoplos (Bleeker, 1849) (Cypriniformes: Cyprinidae), a migratory riverine carp from the Mekong River (Dong Thap province, Vietnam). The new species is assigned to Lissorchiidae by having a combination of features: spinous tegument, subterminal oral sucker, pre-equatorial ventral sucker, median and pretesticular ovary, submarginal genital pore at level of the ventral sucker, follicular vitellarium distributing in 2 lateral fields, and lacking eyespot pigment in the adult. It cannot be assigned to any existing asymphylodorine genus because it has the combination of a well-developed cirrus-sac, an unarmed ejaculatory duct and metraterm, a follicular vitellarium distributing in 2 lateral fields located between the posterior margin of the ventral sucker and the mid-level of the testis, and a sinistral, submarginal genital pore. The new species has an elongate, claviform cirrus-sac, a single, large, elongate-oval testis at the posterior extremity of the body, operculate eggs, and an I-shaped excretory bladder with secondary branches at the level of the testis and extending anteriad to the level of the pharynx. Bayesian inference analysis of the partial large subunit ribosomal DNA gene (28S rDNA) recovered the new species sister to Asaccotrema vietnamienseSokolov and Gordeev, 2019; these species differed by 118 nucleotides (12%; 983 bp fragment). This is the first lissorchiid reported from the Mekong River; only the second from southern Vietnam; and the fourth reported from a cyprinid fish in Vietnam. The aforementioned phylogenetic analysis included previously unpublished sequences representing lissorchiids infecting the intestine of North American suckers (Cypriniformes: Catostomidae): Lissorchis cf. nelsoni from spotted sucker; Minytrema melanops (Rafinesque, 1820) and Lissorchis cf. gullaris (immature) from smallmouth buffalo, Ictiobus bubalus (Rafinesque, 1818). Asymphylodora atherinopsidisAnnereaux, 1947, herein is treated as a species incertae sedis. The 28S tree topology suggests that Lissorchiinae may comprise more than 1 lineage, but additional species are needed to confidently assert this.

Helminth infections in fish in Vietnam: A systematic review.

In Vietnam, fisheries play a key role in the national economy. Helminth infections in fish have a major impact on public health and sustainable fish production. A comprehensive summary of the recent knowledge on fish helminths is important to understand the distribution of parasites in the country, and to design effective control measures. Therefore, a systematic review was conducted, collecting available literature published between January 2004 and October 2020. A total of 108 eligible records were retrieved reporting 268 helminth species, among which are digeneans, monogeneans, cestodes, nematodes and acanthocephalans. Some helminths were identified with zoonotic potential, such as, the heterophyids, opisthorchiids, the nematodes Gnathostoma spinigerum, Anisakis sp. and Capillaria spp. and the cestode Hysterothylacium; and with highly pathogenic potential, such as, the monogeneans of Capsalidae, Diplectanidae and Gyrodactylidae, the nematodes Philometra and Camallanidae, the tapeworm Schyzocotyle acheilognathi, the acanthocephalans Neoechinorhynchus and Acanthocephalus. Overall, these studies only covered about nine percent of the more than 2400 fish species occurring in the waters of Vietnam. Considering the expansion of the aquaculture sector as a part of the national economic development strategy, it is important to expand the research to cover the helminth fauna of all fish species, to assess their potential zoonotic and fish health impacts.

DNA barcoding for identification of some fish species (Carangidae) in Vietnam coastal area

Carangidae family has got about 148 species belonging to 32 genera. In Vietnam, Carangidae is of high commercial value and playing an important role in the ecosystem. In the context Vietnam has received yellow card for seafood since Nov. 2017 by the EU, in which one of the main reasons was related to the restriction of traceability. In this study, DNA barcoding technique of mitochondrial cytochrome oxidase I (COI) gene was used to classify 56 specimens of Carangidae from three coastal areas (Northern, Central and Southern) in Vietnam to evaluate the effectiveness compared to the morphological classification method. Results showed that 21 species belonging to 16 genera were determined by the COI barcode while 18 species (16 genera) were determined when using morphological method. Seriola quinqueradiata and Trachinotus anak were newly recorded in Vietnam. From 56 sequences with 660 bp of mtDNA (COI), total 27 haplotypes were detected; haplotype diversity (h) and nucleotide diversity (π) were 0.903 ± 0.00060 and 0.14%, respectively. The DNA barcodes of COI gene of 21 species in Carangidae which were developed in this study could be used as a basis for comparison and traceability of their products. In addition, the results showed the high potentiality in using COI barcode to identify Carangidae fish in Vietnam.

Extended-spectrum beta-lactamase-producing Escherichia coli harbouring sul and mcr-1 genes isolates from fish gut contents in the Mekong Delta, Vietnam.

This study investigated the existence of sulfonamides and colistin resistance genes among extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli recovered from fish gut in Vietnam and evaluated the susceptibility patterns of the ESBL-producing E. coli to relevant antimicrobials. A total of 88 ESBL-producing E. coli isolates were analysed for the presence of the ESBLs, sul (1, 2, 3) and mcr (1-3) genes by PCR. Antimicrobial resistance phenotypes of isolates were determined by disc diffusion. Results showed that: (i) A high prevalence of 94·3% of sulfonamide resistance was observed in 88 isolates. Moreover, the existence of 2·3% of ESBL-producing E. coli harbouring mcr-1 gene were detected; (ii) The phylogenetic types A and B1 were most frequent, and the blaCTX-M group1 and blaTEM genes encoding ESBL were detected in 47·7% of the isolates; (iii) ESBL-producing E. coli harbouring mcr-1 gene exhibited resistance to 11 antibiotics. The existence of mcr-1 and sul1,2,3 genes and the extremely high level of multiple drug resistance in all ESBL-producing E. coli isolates obtained from sampled fish in Vietnam is a major concern. Therefore, it is imperative to monitor ESBL-producing E. coli in the river waters of Vietnam.

Redescription of Rhadinorhynchus trachuri Harada, 1935 (Acanthocephala: Rhadinorhynchidae) from Marine Fish in Vietnam and California with a Discussion of its Zoogeography.

Rhadinorhynchus trachuri Harada, 1935 is probably one of the most widely distributed acanthocephalans in the world, but the least known taxonomically. This report fills the large gap of knowledge about its taxonomy, host relationships, and worldwide distribution in marine fishes of both sides of the Pacific Ocean and the connecting Indian Ocean. To revisit the taxonomy of this species, provide a more complete morphological description and expand our knowledge about its morphological identity and variations and elaborate on its worldwide zoogeography; accounting for its worldwide distribution based on new collections, museum specimens, and on published reports. Specimens from Vietnam were processed, identified, and documented using standard techniques. Specimens of R. trachuri were studied from three species of fish in three families, Auxis thazard (Lacépède) (Scombridae), Megalaspis cordyla (Linn.) (Carangidae), and Tylosurus sp. (Belonidae) in Nha Trang and Binh Thuan in the south Pacific coast of Vietnam and additional museum specimens mostly from salmonids from the Pacific coast of California were also studied. Extensive research was conducted on published records of R. trachuri and its marine fish hosts worldwide. Specimens of R. trachuri are characterized by cylindrical trunk with anterior rings of spines and posterior ventral and lateral spines, a proboscis usually with 12 hook rows each with 19-24 hooks, variable position of testes, and a long uterus, uterine bell attached to the dorsal trunk wall, rounded vagina, and unusually dorsal gonopore. The hosts and geographical distribution of R. trachuri suggest a northern linkage of infections between the Asian and American Pacific populations across the Bering Sea involving salmonid fishes and a southern linkage through the Indian Ocean involving Carangid fishes. Other hosts involved in the cycling and distribution of infections are also discussed with some definitive hosts also serving as paratenic hosts. This is the first complete description about R. trachuri and the first comprehensive accounting of its worldwide distribution in 19 species of marine fish in seven families. Considerable intraspecific variability related to geographical restrictions, intermediate and definitive host specificity and distribution, and host feeding behavior was documented.

Asaccotrema vietnamiense n. gen.; n. sp. (Trematoda: Monorchioidea), a new aberrant representative of lissorchiid trematodes from the sidestripe rasbora, Rasbora paviana Tirant (Actinopterygii: Cyprinidae), Vietnam.

In this paper we erect Asaccotrema n. gen. of Lissorchiidae Magath, 1917 (Trematoda, Monorchioidea) and provide a description of Asaccotrema vietnamiense n. sp., that infects freshwater fish in Vietnam. The morphology of Asaccotrema n. gen. is significantly different from that of other lissorchiid genera due to the absence of the cirrus-sac, and position of the genital pore sublaterally, near the middle level of the esophagus. The male terminal genitalia are characterized by the presence of the seminal vesicle, which is surrounded by prostate gland-cells, a tubular pars prostatica and a long unarmed ejaculatory duct. The terminal portion of the cluster of prostate gland-cells, which surrounds pars prostatica and the distal end of seminal vesicle, is covered with a thin-walled open-ended membrane, and the other constituents of the male terminal genitalia are naked. Asaccotrema vietnamiense n. sp. specimens are found as progenetic metacercariae on the liver of the sidestripe rasbora, Rasbora paviana Tirant (Actinopterygii: Cyprinidae). A partial sequence was obtained for the 28S rRNA gene (rDNA) of A. vietnamiense n. sp. The 28S rDNA-based phylogenetic analyses support the integration of A. vietnamiense n. sp. into the Lissorchiidae clade, which also includes Lissorchis kritskyi Barnhart Powell, 1979 and Asymphylodora perccotti Besprozvanykh, Ermolenko Atopkin, 2012. This is the second record of a lissorchiid species in fish in Vietnam.

An overview of studies on early life history of fish in Vietnam

Early stages from fertilized eggs to juveniles are important in the existence and development cycles of fish. At these stages, fish are still not fully developed, and are thus easily affected by environmental factors. Vietnam has a rich fish diversity, with ca. 3000 species, and fishery resources play significantly roles not only in the daily lives of local residents but also in national economic development. Ichthyological studies in Vietnam have focused mainly on matured fish while early life history has so far been less researched. This paper presents an overview of studies in Vietnam related to early stages of fish and provides an orientation for this field in future.

Value chain development in Vietnam: a look at approaches used and options for improved impact

Despite the widespread use of value chain development (VCD) approaches to poverty reduction, there has been limited debate on how VCD is implemented in the field, from the approaches, methods, and tools used, to the investments and partnerships made. The article presents five case studies: tea, dairy, horticulture, cinnamon, and fish in Vietnam. For each case, we conducted interviews with development agencies, producer organizations, and principal buyers. The cases examined how VCD interventions were designed, the role of different stakeholders in the implementation process, and the challenges faced by practitioners and chain actors to achieve impact at scale. Results suggest that VCD interventions tended to focus on supporting smallholder participation in high-value, fast-growing markets, but based on a narrow set of activities, mainly around upgrading smallholder production capacities and establishing producer associations. Overall, collaboration with downstream buyers and service providers was muted and, in a few cases, non-existent. Opportunities for increased impact exist based on increased collaboration between practitioners and researchers to employ VCD tools in specific contexts, as well as to design new tools for addressing specific needs and facilitate joint learning on the implementation process and related outcomes. The findings also suggest a need for dedicated approaches to supporting producer organizations, given their central role in the implementation of VCD interventions.

Comparative Risk of Liver and Intestinal Fluke Infection from Either Wild-Caught or Cultured Fish in Vietnam.

A survey for fish-borne zoonotic trematode (FZT) metacercariae in fish from the Northern Mountain Region of Vietnam was conducted from May to August 2014. The major objective was to evaluate the impact of water body types on the prevalence of FZT. A total of 846 fish (31 species) were collected from three water body types, including aquaculture ponds, rivers, and reservoirs. A pepsin digestion method was used for the recovery of metacercariae from fish. Overall, 29 of the 31 fish species were infected with FZTs. Prevalence was 56.8% in river fish, 46.7% in pond fish, and 29.3% in reservoir fish. The prevalence of Clonorchis sinensis metacercariae was 10.6% in reservoir fish, and 2.6% in river fish; fish from ponds were uninfected. The infection intensity of C. sinensis was 29.7 metacercariae/reservoir fish and 2.1 metacercariae/river fish. The prevalence of C. sinensis was highest (25.9%) in Toxabramis houdemeri. The intestinal flukes Haplorchis pumilio, Haplorchis taichui, Haplorchis yokogawai, Centrocestus formosanus and Procerovum varium were recovered from 29 fish species, with an overall prevalence of 46.8% and a mean infection intensity of 23.6 metacercariae. The results indicate that a C. sinensis sylvatic cycle involving wild fish species is important in the epidemiology of liver fluke and that consumption of raw or inadequately prepared wild-caught fish is a the major risk factor for human Clonorchiasis in this region. Both wild-caught and cultured fish present a high risk for infection with intestinal flukes. The habitat requirements of the snail host may be the important determining factor in favoring a sylvatic cycle of C. sinensis. This information is relevant to the development of effective prevention and control strategies, and emphasizes the priority that must be given to education of the local communities on the risks of consuming raw or improperly prepared fish dishes.

Initial research of application of astaxanthin rich Haematococcus pluvialis biomass as supplenent dietary for salmon fish in Vietnam

Initial research of application of astaxanthin rich Haematococcus pluvialis biomass as supplenent dietary for salmon fish in Vietnam

Attitude, Social Norms, Perceived Behavioral Control, Past Behavior, and Habit in Explaining Intention to Consume Fish in Vietnam

The purpose of this study is to discuss and test the direct and moderating effects of attitudes, social norms, perceived behavioral control (PBC), past behavior, and habit strength in explaining Vietnamese consumers’ intention to consume fish. In addition to a data set of 466 consumers in a coastal province in Central Vietnam and structural equation modelling, a model development strategy with six nested models is used to test hypotheses. Results indicate that attitude, social norms, and PBC have a positive effect on intention. Both past behavior and habit strength have a significantly positive influence on intention and considerably increase the explained variance of intention. In particular, the results also indicate that habit strength, past behavior, and social norms negatively moderate the impact of attitudes on intention. All of these findings emphasize the importance of past behavior and habit strength as well as interactions within the theory of planned behavior in explaining intention to consume fish in Vietnam.

Attitude, Social Norms, Perceived Behavioral Control, Past Behavior, and Habit in Explaining Intention to Consume Fish in Vietnam

Attitude, Social Norms, Perceived Behavioral Control, Past Behavior, and Habit in Explaining Intention to Consume Fish in Vietnam

Evaluation of the microbiological safety and quality of Vietnamese Pangasius hypophthalmus during processing by a microbial assessment scheme in combination with a self-assessment questionnaire

Pangasius hypophthalmus (referred to as Pangasius or tra fish in Vietnam) has become highly appreciated by consumers in the European Union, USA, Japan, etc. and is of worldwide economic importance. Therefore, the microbial quality and safety of Pangasius fish processed for export was assessed by means of a microbial assessment scheme throughout the entire production process. A total of 144 samples were collected from various processing steps and analyzed. It was determined that the microbial safety and quality of the products was not guaranteed as the contamination levels remained high throughout processing. Escherichia coli, Staphylococcus aureus and Vibrio cholerae were present on the hands of food operators, particularly those in the packaging area. Moreover, the presence of Listeria monocytogenes (1 positive out of 9 samples) and V. cholerae (4/9) on the final products was likely a result of inadequate hygiene practices in the processing environment. Also discussed in this paper are the results of a self-assessment questionnaire, which provide insight into the performance of the food safety management system currently implemented at the company. These data are of major importance in order to contribute valuable information to the local and international trade point of view in general and to the intended customers in particular.

Attitude toward and Consumption of Fish in Vietnam

This study uses theory of planned behaviour (TPB) as a conceptual framework to investigate the attitude and intention toward the consumption of fish in a cross-sectional survey of Vietnamese consumers. Structural equation modelling (SEM) is used to test the reliability, validity, and relationships in the proposed model. The results show that the variation in the frequency of fish consumption is significantly explained by intention and perceived behavioural control. Intention to consume fish is significantly determined by subjective norms and attitude toward consuming fish as a meal. Perceived behavioural control is significantly related to fish consumption, but not to the intention to consume fish, indicating that there may be a difference between perceived control and actual control. At the specific-belief level, the study found that negative affect, perceived quality, and price are significant indicators that explain 60% of the variation in attitude. Perceived price, time needed to cook and prepare fish as a meal, and the availability of fresh fish are important factors explaining 63% of the variation of the perceived control over fish consumption. The study also provides some managerial implications and suggestions for the seafood sector to expand the domestic markets and gives recommendations for future research.