Cell-cultivated aquatic food products: emerging production systems for seafood.

The demand for fish protein continues to increase and currently accounts for 17% of total animal protein consumption by humans. About 90% of marine fish stocks are fished at or above maximum sustainable levels, with aquaculture propagating as one of the fastest growing food sectors to address some of this demand. Cell-cultivated seafood production is an alternative approach to produce nutritionally-complete seafood products to meet the growing demand. This cellular aquaculture approach offers a sustainable, climate resilient and ethical biotechnological approach as an alternative to conventional fishing and fish farming. Additional benefits include reduced antibiotic use and the absence of mercury. Cell-cultivated seafood also provides options for the fortification of fish meat with healthier compositions, such as omega-3 fatty acids and other beneficial nutrients through scaffold, media or cell approaches. This review addresses the biomaterials, production processes, tissue engineering approaches, processing, quality, safety, regulatory, and social aspects of cell-cultivated seafood, encompassing where we are today, as well as the road ahead. The goal is to provide a roadmap for the science and technology required to bring cellular aquaculture forward as a mainstream food source.

The concept of "state fishes of India": Current status, knowledge gaps, and strategic plans for conservation and sustainable utilization.

The concept of "state fishes of India" highlights the importance and significance of the prioritized fish species distributed across various states within the country. This review article systematically documents the current status of state fishes from various perspectives, identifies the prevailing knowledge gaps, and also highlights the issues and strategic plans essential for the conservation and sustainable utilization of these valuable genetic resources. A total of 8357 publications were checked for the consolidated information on state fish species, and the appropriate items were selected under eight categories: biology, physiology and nutrition, aquaculture, habitat and environmental parameters, genetics and biotechnology, harvest and postharvest, fish health management, and others. The synthesized information was used to present the current status of research and development on state fish species. The knowledge gaps that are to be addressed are also depicted under the perspectives of fisheries management and conservation aquaculture. Based on the findings, strategic plans for the targeted conservation programmes are proposed and discussed under various in situ and ex situ conservation measures. Further, the departmental processes involved in the declaration, the importance of stakeholder involvement, namely, local communities and policymakers, in fostering effective conservation measures, and planning for utilization of these valuable fish genetic resources are also indicated.

Cellular Aquaculture: Prospects and Challenges.

Aquaculture plays an important role as one of the fastest-growing food-producing sectors in global food and nutritional security. Demand for animal protein in the form of fish has been increasing tremendously. Aquaculture faces many challenges to produce quality fish for the burgeoning world population. Cellular aquaculture can provide an alternative, climate-resilient food production system to produce quality fish. Potential applications of fish muscle cell lines in cellular aquaculture have raised the importance of developing and characterizing these cell lines. In vitro models, such as the mouse C2C12 cell line, have been extremely useful for expanding knowledge about molecular mechanisms of muscle growth and differentiation in mammals. Such studies are in an infancy stage in teleost due to the unavailability of equivalent permanent muscle cell lines, except a few fish muscle cell lines that have not yet been used for cellular aquaculture. The Prospect of cell-based aquaculture relies on the development of appropriate muscle cells, optimization of cell conditions, and mass production of cells in bioreactors. Hence, it is required to develop and characterize fish muscle cell lines along with their cryopreservation in cell line repositories and production of ideal mass cells in suitably designed bioreactors to overcome current cellular aquaculture challenges.

DNA barcoding Indian freshwater fishes.

DNA barcoding is a promising technique for species identification using a short mitochondrial DNA sequence of cytochrome c oxidase I (COI) gene. In the present study, DNA barcodes were generated from 72 species of freshwater fish covering the Orders Cypriniformes, Siluriformes, Perciformes, Synbranchiformes, and Osteoglossiformes representing 50 genera and 19 families. All the samples were collected from diverse sites except the species endemic to a particular location. Species were represented by multiple specimens in the great majority of the barcoded species. A total of 284 COI sequences were generated. After amplification and sequencing of 700 base pair fragment of COI, primers were trimmed which invariably generated a 655 base pair barcode sequence. The average Kimura two-parameter (K2P) distances within-species, genera, families, and orders were 0.40%, 9.60%, 13.10%, and 17.16%, respectively. DNA barcode discriminated congeneric species without any confusion. The study strongly validated the efficiency of COI as an ideal marker for DNA barcoding of Indian freshwater fishes.

Multidrug efflux pumps from Enterobacteriaceae, Vibrio cholerae and Staphylococcus aureus bacterial food pathogens.

Foodborne illnesses caused by bacterial microorganisms are common worldwide and constitute a serious public health concern. In particular, microorganisms belonging to the Enterobacteriaceae and Vibrionaceae families of Gram-negative bacteria, and to the Staphylococcus genus of Gram-positive bacteria are important causative agents of food poisoning and infection in the gastrointestinal tract of humans. Recently, variants of these bacteria have developed resistance to medically important chemotherapeutic agents. Multidrug resistant Escherichia coli, Salmonella enterica, Vibrio cholerae, Enterobacter spp., and Staphylococcus aureus are becoming increasingly recalcitrant to clinical treatment in human patients. Of the various bacterial resistance mechanisms against antimicrobial agents, multidrug efflux pumps comprise a major cause of multiple drug resistance. These multidrug efflux pump systems reside in the biological membrane of the bacteria and actively extrude antimicrobial agents from bacterial cells. This review article summarizes the evolution of these bacterial drug efflux pump systems from a molecular biological standpoint and provides a framework for future work aimed at reducing the conditions that foster dissemination of these multidrug resistant causative agents through human populations.

DNA barcoding detected improper labelling and supersession of crab food served by restaurants in India.

BACKGROUND: Detection of improper labelling of raw and processed seafood is of global importance for reducing commercial fraud and enhancing food safety. Crabs are crustaceans with intricate morphological as well as genetic divergence among species and are popular as seafood in restaurants. Owing to the high number of crab species available, it can be difficult to identify those included in particular food dishes, thus increasing the chance of supersession. DNA barcoding is an advanced technology for detecting improper food labelling and has been used successfully to authenticate seafood. RESULTS: This study identified 11 edible crab species from India by classical taxonomy and developed molecular barcodes with the cytochrome c oxidase I (COI) gene. These barcodes were used as reference barcodes for detecting any improper labelling of 50 restaurant crab samples. Neighbour-joining tree analysis with COI barcodes showed distinct clusters of restaurant samples with respective reference species. The study demonstrated 100% improper labelling of restaurant samples to cover up acts of inferior crab supersession. CONCLUSION: DNA barcoding successfully identified 11 edible crabs in accordance with classical taxonomy and discerned improper crab food labelling in restaurants of India.

In vitro cytotoxicity assessment of two heavy metal salts in a fish cell line (RF).

Labeo rohita (rohu) is one of most important of Indian major carps, which is highly ranked among the important freshwater aquaculture species in the world. Heavy metals are major risk factors for aquatic health, which are biomagnified through the food chain. The present study was carried out to investigate the effect of different divalent salts of two heavy metals, such as zinc (ZnCl(2), ZnSO(4) and ZnNO(3)) and cadmium (CdCl(2) and CdSO(4)), in an established fish cell line, RF developed from fin tissue of L. rohita. The RF cell line was used for assessment of heavy metal cytotoxicity through various endpoint assays, including maximum tolerated dose (MTD) determination, 3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) assay, neutral red (NR) uptake assay, and Coomassie brilliant blue (CBB) assay. Results revealed that these heavy metal salts were cytotoxic to the RF cell line at varied concentrations. MTD values were found to be 1.563, 3.125, 6.25, 12.5 and 25 mg/L for CdCl(2), CdSO(4), ZnCl(2), Zn(NO(3))(2) and ZnSO(4), respectively. The half-maximal inhibitory concentration values calculated by MTT, NR and CB assay were 53.83 ± 7.02, 58.03 ± 9.12 and 79.20 ± 15.27 for ZnSO(4), 26.44 ± 7.01, 36.60 ± 7.82 and 155.6 ± 14.75 for Zn(NO(3))(2), 20.26 ± 17.95, 16.94 ± 7.05 and 87.54 ± 7.58 for ZnCl(2), 5.166 ± 0.57, 15 ± 1 and 41.80 ± 8.38 for CdSO(4) and 4.966 ± 0.56, 9.56 ± 1.73 and 20.93 ± 4.47 for CdCl(2). This study establishes the RF cell line as an in vitro tool for assessment and monitoring of heavy metal concentration in the aquatic environment.

Induction of micronuclei and nuclear lesions in Channa punctatus following exposure to carbosulfan, glyphosate and atrazine.

The genotoxic effects of commonly used agricultural pesticides viz., carbosulfan, glyphosate, and atrazine, were evaluated in Channa punctatus (Pisces, Perciformes) using micronucleus (MN) test and induction of nuclear lesions (NL). The 96 h LC50 value were estimated by probit analysis as 0.27, 32.0 and 42.0 mg L(-1), respectively, for carbosulfan, glyphosate, and atrazine using semi-static bioassays. Based on these values, three sublethal test concentrations of carbosulfan (0.07, 0.13, 0.20 mg L(-1)), glyphosate (8.1, 16.3, 24.4 mg L(-1)) and atrazine (10.6, 21.2, 31.8 mg L(-1)) corresponding to », ½ and ¾ of the LC50 of the pesticides respectively, were selected for exposure for 96 h. Peripheral blood samplings were taken at intervals of 24 h for assessment of MN and NL frequencies. Considerably higher genotoxic damage was induced by carbosulfan as compared to glyphosate and atrazine. There were significant effects (p < 0.01) of concentrations in all the treated groups. The induction of MN and NL was highest at 96 h pesticide exposure at all test concentrations. The nuclear abnormalities recorded in this study, such as blebbed-, lobed-, notched- and bi-nuclei, other than micronuclei, are indicators of genotoxic damage.

Fish communities and trophic metrics as measures of ecological degradation: a case study in the tributaries of the river Ganga basin, India.

In India, freshwater aquatic resources are suffering from increasing human population, urbanization and shortage of all kind of natural resources like water. To mitigate this, all the major rivers have been planned for a river-interlinking through an interlinking canal system under a huge scheme; yet, the baseline information on ecological conditions of those tropical rivers and their fish communities is lacking at present. In view of that, the present study was undertaken to assess the ecological condition by comparing the trophic metrics of the fish community, conservation status and water chemistry of the two tropical rivers of the Ganga basin, from October 2007 to November 2009. The analysis of trophic niches of the available fish species indicated dominancy of carnivorous (19 species) in river Ken and omnivorous (23 species) in Betwa. The trophic level score of carnivorous species was recorded similar (33.33%) in both rivers, whereas omnivorous species were mostly found in Betwa (36.51%) than Ken (28.07%). Relatively undisturbed sites of Betwa (B1, B2 and B3) and Ken (K2, K3 and K5) were characterized by diverse fish fauna and high richness of threatened species. The higher mean trophic level scores were recorded at B4 of Betwa and K4 of Ken. The Bray-Curtis index for trophic level identified the carnivorous species (> 0.32) as an indicator species for pollution. Anthropogenic exposure, reflected in water quality as well as in fish community structure, was found higher especially in the lower stretches of both rivers. Our results suggest the importance of trophic metrics on fish community, for ecological conditions evaluation, which enables predictions on the effect of future morphodynamic changes (in the post-interlinking phases), and provide a framework and reference condition to support restoration efforts of relatively altered fish habitats in tropical rivers of India.

Fish communities and trophic metrics as measures of ecological degradation: a case study in the tributaries of the river Ganga basin, India / Métricas tróficas y de comunidades de peces como medidas de la degradación ecológica: un estudio de caso en los afluentes de la cuenca del río Ganga, India

In India, freshwater aquatic resources are suffering from increasing human population, urbanization and shortage of all kind of natural resources like water. To mitigate this, all the major rivers have been planned for a river-interlinking through an interlinking canal system under a huge scheme; yet, the baseline information on ecological conditions of those tropical rivers and their fish communities is lacking at present. In view of that, the present study was undertaken to assess the ecological condition by comparing the trophic metrics of the fish community, conservation status and water chemistry of the two tropical rivers of the Ganga basin, from October 2007 to November 2009. The analysis of trophic niches of the available fish species indicated dominancy of carnivorous (19 species) in river Ken and omnivorous (23 species) in Betwa. The trophic level score of carnivorous species was recorded similar (33.33%) in both rivers, whereas omnivorous species were mostly found in Betwa (36.51%) than Ken (28.07%). Relatively undisturbed sites of Betwa (B1, B2 and B3) and Ken (K2, K3 and K5) were characterized by diverse fish fauna and high richness of threatened species. The higher mean trophic level scores were recorded at B4 of Betwa and K4 of Ken. The Bray-Curtis index for trophic level identified the carnivorous species (>0.32) as an indicator species for pollution. Anthropogenic exposure, reflected in water quality as well as in fish community structure, was found higher especially in the lower stretches of both rivers. Our results suggest the importance of trophic metrics on fish community, for ecological conditions evaluation, which enables predictions on the effect of future morphodynamic changes (in the post-interlinking phases), and provide a framework and reference condition to support restoration efforts of relatively altered fish habitats in tropical rivers of India.

En la India, los recursos acuáticos de agua dulce están sufriendo debido a la creciente población humana, la urbanización y la escasez de todo tipo de recursos naturales como el agua. Para mitigar esto, se ha planificado bajo un amplio esquema que todos los grandes ríos estén interconectados a través de un sistema de canales, sin embargo, la información básica sobre las condiciones ecológicas de los ríos tropicales y sus comunidades de peces es escasa en la actualidad. En vista de ello, el presente estudio se realizó para evaluar el estado ecológico, mediante la comparación de los parámetros tróficos de la comunidad de peces, estado de conservación y el agua de los dos ríos tropicales de la cuenca del Ganges, de octubre 2007 a noviembre 2009. El análisis de los nichos tróficos de las especies de peces disponibles indican dominancia de carnívoros (19 especies) en el río Ken y omnívoros (23 especies) en Betwa. El nivel trófico de las especies carnívoras fue similar en ambos ríos (33.33%), mientras que las especies omnívoras fueron mayores en Betwa (36.51%) que en Ken (28.07%). Sitios relativamente inalterados de Betwa (B1, B2 y B3) y Ken (K2, K3 y K5) se caracterizaron por la alta diversidad y riqueza de especies de peces amenazadas. Los puntajes medios más altos del nivel trófico se registraron en B4 de Betwa y K4 de Ken. El índice de Bray-Curtis para el nivel trófico identificó las especies carnívoras (>0.32) como indicadoras de contaminación. Exposición antropogénica, reflejada en la calidad del agua, así como en la estructura de la comunidad de peces, fue más alta, especialmente en los tramos inferiores de ambos ríos. Nuestros resultados sugieren la importancia de métricas tróficas en la comunidad de peces, para la evaluación de las condiciones ecológicas, lo que permite hacer predicciones sobre el efecto de futuros cambios morfodinámicos (en las fases de post-interconexión), y proporcionar un marco y condición de referencia para apoyar los esfuerzos de restauración de hábitat de peces relativamente alterados en los ríos tropicales de la India.

Genetic relatedness and phylogenetics of five Indian pufferfishes.

The taxonomy and phylogeny of the pufferfishes belonging to the family Tetraodontidae found in India are poorly understood. We investigated five species of freshwater and marine pufferfishes using partial sequences of 16S rRNA and cytochrome c oxidase subunit I (COI) of mitochondrial genes. The sequence alignment of 16S rRNA yielded 573 bp, whereas COI gene sequence alignment yielded 614 bp. The sequence analysis of the genes revealed two distinct groups of freshwater and marine origin, which are genetically distinct from each other and exhibit identical phylogenetic resolution. The partial sequences of both the genes provided sufficient phylogenetic resolution to distinguish all the five species of pufferfishes. The COI sequences could be used as DNA barcodes for identification of the pufferfishes.

Permanent genetic resources added to molecular ecology resources database 1 December 2012-31 January 2013.

This article documents the addition of 268 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Alburnoides bipunctatus, Chamaerops humilis, Chlidonias hybrida, Cyperus papyrus, Fusarium graminearum, Loxigilla barbadensis, Macrobrachium rosenbergii, Odontesthes bonariensis, Pelteobagrus vachelli, Posidonia oceanica, Potamotrygon motoro, Rhamdia quelen, Sarotherodon melanotheron heudelotii, Sibiraea angustata, Takifugu rubripes, Tarentola mauritanica, Trimmatostroma sp. and Wallago attu. These loci were cross-tested on the following species: Alburnoides fasciatus, Alburnoides kubanicus, Alburnoides maculatus, Alburnoides ohridanus, Alburnoides prespensis, Alburnoides rossicus, Alburnoides strymonicus, Alburnoides thessalicus, Alburnoides tzanevi, Carassius carassius, Fusarium asiaticum, Leucaspius delineatus, Loxigilla noctis dominica, Pelecus cultratus, Phoenix canariensis, Potamotrygon falkneri, Trachycarpus fortune and Vimba vimba.

Genetic differentiation of Ompok bimaculatus (Teleostei: Siluridae) population based on mtDNA cytochrome b gene.

Ompok bimaculatus commonly called as Indian butter catfish is a commercially important food fish and distributed throughout India and Southeast Asia. Genetic differentiation of O. bimaculatus was investigated using cytochrome b (cyt b) gene of three different riverine populations. A total of 37 sequences of cyt b gene (1118 bp) were generated from O. bimaculatus. The mitochondrial DNA analysis revealed that O. bimaculatus has relatively high genetic diversity. The estimated haplotype and nucleotide diversity were 0.063 and 0.005, respectively. The analysis of molecular variance indicated 73.53% genetic variability between the populations and 26.47% genetic variation within population. The understanding of genetic differentiation of O. bimaculatus populations will play a key role in conservation and management of the important endangered fish species.

Morphological taxonomy and molecular divergence of four balitorid species (subfamily: Nemachelinae) from Central Himalaya, India.

The fishes in this study belong to the difficult group. It is difficult to identify about more than 50 nemacheilid loach species in India, mainly due to the poor quality of the original descriptions, the lack of good reviews, and the similarity of a number of the banded species. In view of this, a morphometric and genetic study was conducted on four species that have been documented in Central Himalayan region of India. Using comparative methods, a contribution to the knowledge about the variability of four Himalayan hillstream loaches, a molted loach Acanthocobitis botia (Hamilton, 1822), Nemacheilus corica (Hamilton, 1822), a creek loach Schistura beavani (Gunther, 1868), and Schistura montana (McClelland, 1838), was accomplished. Morphometric data were analyzed by univariate (CV and analysis of variance) and multivariate analyses (discriminant function analysis and cluster analysis). Based on the results of these statistical analyses, generally all four species grouped into their own species cluster with minimal overlap between two species of genus Schistura. Mitochondrial DNA cytochrome b (Cyt b) gene analysis revealed 7.7-17.6% genetic distances among the four species. Molecular phylogenetic relationship among these species and other Balitoridae species was investigated using published mitochondrial Cyt b sequences. Dendrograms obtained by the maximum likelihood and maximum parsimony method analyses exhibited the same topology. According to this topology, all the four species represented distinct species group and A. botia form the most distinct species while S. beavani and S. montana are clustered together with Nemacheilus species to form a single group. This work may build the base for the revision of taxonomic identity of fishes of the family Balitoridae. The results may further help to enhance the knowledge of the ichthyologists in understanding the fish fauna of India and assist them in planning conservation and management strategies for the propagation of these less studied small indigenous species along their natural range of distribution.

Molecular identification of three Ompok species using mitochondrial COI gene.

A DNA-based barcode identification system that is applicable to all animal species will provide a simple, universal tool for the identification of fish species. The barcode system is based on sequence diversity in subunit 1 cytochrome c oxidase (COI) gene. Identification and characterization of fish species based on morphological characters are sometimes found to be erroneous and environmentally affected. There are no studies on the genus Ompok in India at molecular level and species identification of the Ompok is usually carried out through morphological features. A total of 106 samples from three species Ompok pabda, O. pabo and O. bimaculatus were collected from eight sampling sites of seven Indian rivers. One hundred and six sequences were generated from COI region of three Ompok species and 21 haplotypes were observed. The sequence analysis of COI gene revealed three genetically distinct Ompok species and exhibited identical phylogenetic resolution among them. The partial COI gene sequence can be used as a diagnostic molecular marker for identification and resolution of taxonomic ambiguity of Ompok species.

Investigation on acute toxicity and behavioral changes in Channa punctatus (Bloch) due to organophosphate pesticide profenofos.

Acute toxicity of an organophosphate pesticide profenofos (O-4-bromo-2- chlorophenyl-O-ethyl S-propyl phosphorothioate) to freshwater fish, Channa punctatus (Bloch), was studied in a static bioassay. Estimated 96-hour LC(50) of profenofos was found to be 2.68 µgL(-1). On the basis of the obtained LC(50) values for 96-hour exposure intervals, profenofos can be rated as highly toxic to C. punctatus. Fish exposed to profenofos showed hyper excitability, discoloration, erratic swimming, and secretion of excess amounts of mucus on the body and gills with eventual exhaustion and death.

Development and characterization of two cell lines PDF and PDH from Puntius denisonii (Day 1865).

The Puntius denisonii colloquially and more popularly referred to as Miss Kerala is a subtropical fish belonging to the genus Puntius (Barb) and family Cyprinidae. Two cell lines PDF and PDH were developed from the caudal fin and heart of P. denisonii, respectively. The cell lines were optimally maintained at 26°C in Leibovitz-15 medium supplemented with 10% fetal bovine serum. A diploid count of 50 chromosomes at passage 50 was observed in both the cell lines. The high growth potential of the cell lines was reflected from the cell doubling time of 28 and 30 h of PDF and PDH cell lines, respectively. The viability of the PDF and PDH cell lines was 70% and 76%, respectively, after 4 mo of storage in liquid nitrogen (-196°C). The origin of the cell lines was confirmed by the amplification of 653 bp fragments of cytochrome oxidase subunit I of mitochondrial DNA genes.

Toxicity of the herbicide atrazine: effects on lipid peroxidation and activities of antioxidant enzymes in the freshwater fish Channa punctatus (Bloch).

The present study was undertaken to evaluate the toxicity and effects of a commercial formulation of the herbicide atrazine (Rasayanzine) on lipid peroxidation and antioxidant enzyme system in the freshwater air breathing fish Channa punctatus. The 12, 24, 48, 72 and 96 h LC(50) of atrazine, calculated by probit analysis, were determined to be 77.091, 64.053, 49.100, 44.412 and 42.381 mg·L(-1), respectively, in a semi static system with significant difference (p < 0.05) in LC(10-90) values obtained for different times of exposure. In addition to concentration and time dependent decrease in mortality rate, stress signs in the form of behavioral changes were also observed in response to the test chemical. In fish exposed for 15 days to different sublethal concentrations of the herbicide (1/4 LC(50) = ∼10.600 mg·L(-1), 1/8 LC(50) = ∼5.300 mg·L(-1) and 1/10 LC(50) = ∼4.238 mg·L(-1)) induction of oxidative stress in the liver was evidence by increased lipid peroxidation levels. The antioxidants superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GR) responded positively in a concentration dependent pattern, thus, suggesting the use of these antioxidants as potential biomarkers of toxicity associated with contaminations exposure in freshwater fishes.

Development and characterization of three new diploid cell lines from Labeo rohita (Ham.).

Development of cell lines from fish for identifying the pathogenesis of viral diseases and for vaccine production against viral and bacterial diseases is imperative where they are of commercial importance. Three new diploid fish cell lines (RF, RH, and RSB) were developed from fin, heart, and swim bladder of an Indian major carp, Labeo rohita, commonly called Rohu. All the cell lines were optimally maintained at 28 degrees C in Leibovitz-15 medium supplemented with 10% FBS. The propagation of RH and RSB cells was serum dependent, with a low plating efficiency (<16%), whereas RF cells showed 20% efficiency. The cytogenetic analysis revealed a diploid count of 50 chromosomes. The cells of RF and RSB were found to be epithelial, where as the cells of RH were mostly fibroblastic. The viability of the RF, RH, and RSB cell lines was 75, 70 and 72%, respectively after 6 months of storage in liquid nitrogen. The origin of the cell lines was confirmed by the amplification of 496 and 655 bp fragments of 16S rRNA and Cytochrome Oxidase Subunit I (COI) of mtDNA. The new cell lines would facilitate viral disease diagnosis and genomic studies.

Nucleotide sequences and chromosomal localization of 45S and 5S rDNA in Neolissochilus hexagonolepis (Pisces, Cyprinidae), using dual-color fish.

Dual-color fluorescence in situ hybridization (FISH) was performed to study the simultaneous localization of major (45S) and minor (5S) family ribosomal RNA genes on chromosomes of Neolissochilus hexagonolepis. The partial 45S (18S, ITS 1, 5.8S, ITS 2 and 28S) and complete 5S (coding and NTS) rDNA units were amplified, sequenced, analyzed, and mapped on the metaphase chromosomes. The complete 18S, 5.8S and partial 28S rDNAs were 1849 bp, 157 bp and 1819 bp long, respectively. Internal transcribed spacers, namely ITS 1 (828 bp) and ITS 2 (359 bp), showed significant nucleotide variations from other fish species listed in NCBI database. The 5S rDNA contained an identical coding region of 120 bp and a highly divergent, non-transcribed 81-bp spacer. The specimens of N. hexagonolepis showed six bright fluorescent signals of 18S, while the 5S signals were present only on one pair of chromosomes. Subsequent analyses between conventional Ag-NORs and 18S rDNA FISH strongly suggested the possible inactivation of one pair of NORs that was localized at a telomeric position of a submetacentric chromosome. The sequencing and chromosomal localization of 45S and 5S rDNAs may serve as a useful genetic marker in taxonomic classification as well as in phylogenetic and evolutionary studies.