Important Food Fish Research Articles

Morphometric Characters and Sex Ratio of the Freshwater Garfish, Xenentodon Cancila Collected From Different Waters of Jashore, South-Western Bangladesh

The freshwater garfish, Xenentodon cancila is one of the important food fish in Bangladesh. The size class distribution, length-weight relationships, and sex ratio of X. cancila are described in the present study. A total of 138 specimens were collected randomly for a year from the local fish markets and/or direct from fishermen who fish primarily in nearby waters (Beel, Canal and Baor) of Jashore, southwestern Bangladesh. Most individuals were collected in the rainy season and their mean size was larger compare to the other two seasons (summer and winter). The maximum size recorded 254.1 mm total length (TL) and 38.05 g body weight (BW). The mean TL and BW were 166.35±38.17 mm and 11.16±7.47g, respectively. Most of the individuals belonged to the size class of 141-180 mm. The length-weight relationship (LWR) was strongly correlated as the regression value was 0.876 and the relationships were linear in both sexes. The allometric coefficient ‘b’ of the LWR indicated nearly positive allometric growth and the value was 2.98. The male fishes were dominant over females and the ratio was 1: 0.77. These research outcomes would be useful for the researcher to better understand the biological aspects of freshwater garfish in the nearby waters of Jashore area in south-western Bangladesh. J. Bio-Sci. 29(1): 23-31, 2021 (June)

Lipid peroxidation and antioxidant levels in Anabas testudineus (Bloch) under naphthalene (PAH) stress

Exposure to large concentrations of organic PAH (polycyclic aromatic hydrocarbon) compound naphthalene can potentially accumulate inside the body, damage the cells and causes serious health issues. The current understanding of naphthalene exposure to many food fish species is limited. For a comprehensive understanding of naphthalene toxicity to fish health, dose dependent exposure was carried out in Anabas testudineus, an important food fish of Asia. Fish were exposed to sublethal concentrations of naphthalene (4.2, 4.4, 4.6, 4.8 and 5 mg L−1) for a period of 72 h. Activity analysis of lipid peroxidation and antioxidant enzymes in liver and muscles of the Anabas testudineus showed a marked increase in the lipid peroxidation activity in almost all the experimental groups. In contrast, the enzymatic activity of antioxidants like catalase, glutathione peroxidase and non-enzymatic antioxidant glutathione decreased in both liver and muscle tissue. The results imply that increasing doses of naphthalene induced lipid peroxidation and the decreasing levels of antioxidants were incapable of reducing the stress exerted by naphthalene. This study is beneficial for evaluating the effect of LMW (Low molecular weight) naphthalene on fish and highlights the specific biomarker response signifying PAHs toxicity in fish.

Association between the Polymorphisms of fads2a and fads2b and Poly-Unsaturated Fatty Acids in Common Carp (Cyprinus carpio)

Simple SummaryFishes are the major dietary source of polyunsaturated fatty acids (PUFAs) for humans. The limited availability of PUFAs derived from fish represents a critical bottleneck in food production systems, one that numerous research institutions and aqua-feed companies in this field are trying to overcome. This problem could be minimized by select-bred fish to be capable of more effectively producing endogenous PUFAs. Fatty acid desaturase 2 (fads2) is one of the rate-limiting enzymes in the synthesis of PUFAs. The common carp, one of the most important food and ornamental allo-tetraploid fish, encodes two fads2 genes (fads2a and fads2b). The PUFA contents among common carp individuals were numerous, suggesting that there might exist polymorphisms in fads2a and fads2b. However, selective breeding of common carp with high PUFA contents was hindered due to a lack of effective molecular markers. This study investigated the contents of PUFAs in common carp and identified polymorphisms in the CDS regions of fads2a and fads2b. The association study identified three cSNPs associated with the PUFA contents and suggested that fads2b might be the major gene responding for common carp PUFA contents. These cSNPs would be potential markers for future selection to improve the PUFA contents in common carp.Fatty acid desaturase 2 (fads2) is one of the rate-limiting enzymes in PUFAs biosynthesis. Compared with the diploid fish encoding one fads2, the allo-tetraploid common carp, one most important food fish, encodes two fads2 genes (fads2a and fads2b). The associations between the contents of different PUFAs and the polymorphisms of fads2a and fads2b have not been studied. The contents of 12 PUFAs in common carp individuals were measured, and the polymorphisms in the coding sequences of fads2a and fads2b were screened. We identified five coding single nucleotide polymorphisms (cSNPs) in fads2a and eleven cSNPs in fads2b. Using the mixed linear model and analysis of variance, a synonymous fads2a cSNP was significantly associated with the content of C20:3n-6. One non-synonymous fads2b cSNP (fads2b.751) and one synonymous fads2b cSNP (fads2b.1197) were associated with the contents of seven PUFAs and the contents of six PUFAs, respectively. The heterozygous genotypes in both loci were associated with higher contents than the homozygous genotypes. The fads2b.751 genotype explained more phenotype variation than the fads2b.1197 genotype. These two SNPs were distributed in one haplotype block and associated with the contents of five common PUFAs. These results suggested that fads2b might be the major gene responding to common carp PUFA contents and that fads.751 might be the main effect SNP. These cSNPs would be potential markers for future selection to improve the PUFA contents in common carp.

Genetic variation in the Asian seabass (Lates calcarifer Bloch, 1790) from Wallacea Region estimated using random amplified polymorphic DNA (RAPD) markers

The Asian seabass (Lates calcarifer) is an important marine food fish in Southeast Asia. To facilitate a selective breeding program conducted in Indonesia, we genotyped 29 Asian seabass specimens collected from four wild populations in the Wallacea Region originating from coastal waters in two seaways: the Makassar Strait (Bulungan in North Kalimantan and Maros in South Sulawesi) and the Gulf of Bone (Siwa and Bone in South Sulawesi). We used four polymorphic markers with a random amplified polymorphic DNA (RAPD) method. A total of 43 alleles were detected at four loci across the four populations, four of which were shared by all the accessions while 39 were polymorphic. Of these 43 alleles, 34.88% were unique, with 46.67% in the Gulf of Bone and 53.33% in the Makassar Strait. Asian seabass within-population genetic distance was greater in Bone Bay than the Makassar Strait, and an ongoing speciation phenomenon is suspected. The greatest genetic distance (0.291) was between the Asian seabass populations from Bulungan, North Kalimantan and Cenranae River estuary, Bone Regency; the lowest (0.086) was between the Bulungan and Maros populations. In the phylogenetic analysis, Gulf of Bone and Makassar Strait specimens formed separate clades. Commercial scale cross-breeding between Asian seabass from Makassar Strait and the Gulf of Bone may produce highly adaptable seed. These results will be helpful in future Asian seabass breeding programs as well as for optimising management and conservation strategies for wild Asian seabass populations.

Two SNPs in SNX2 are associated with SGIV resistance in Asian seabass

Breeding for disease resistance is an important task for genetic improvement in aquaculture. Identification of DNA markers associated with disease resistance is a critical step towards molecular breeding for disease resistance. Iridovirus causes mass mortality in hatchery of an important food fish Asian seabass (Lates calcarifer). In this study, an SNX2 (Sorting nexin 2) homolog (LcaSNX2) from L. calcarifer was cloned. Its roles in the infection of Singapore grouper iridovirus (SGIV) were characterized. The gene contained an ORF of 1542 bp encoding 513 amino acids, a 5’ UTR of 242 bp and a 3′ UTR of 2650 bp. Two SNPs in the 3’ UTR of the gene were identified, and they were significantly associated with SGIV resistance. Thus, they provide useful DNA markers for selecting Asian seabass juveniles for resistance against SGIV. The SNX2 gene was expressed ubiquitously in healthy fish, and highly expressed in the eye, gill, fin and brain. The expression of the gene was induced after SGIV infection in vitro, suggesting that LcaSNX2 plays a role in virus-host interaction during SGIV infection. Overexpression of LcaSNX2 increased the infection and replication of SGIV. Knockdown of this gene reduced viral gene transcriptional level, cytopathic effect and virus titer, indicating that suppression of the gene reduces SGIV infection. These data indicate that LcaSNX2 gene is essential for efficient replication of SGIV.

Morphological and genetic evaluation of the thumbprint emperor, Lethrinus harak (Forsskål, 1775) in the Pacific and Indian Oceans

Background: The Lethrinidae (emperors) include many important food fish species. Accurate determination of species and stocks is important for fisheries management. The taxonomy of the genus Lethrinus is problematic, for example with regards to the identification of the thumbprint emperor Lethrinus harak. Little research has been done on L. harak diversity in the Pacific and Indian Oceans. This study aimed to evaluate the morphometric and genetic characters of the thumbprint emperor, L. harak (Forsskål, 1775) in the Pacific and Indian Oceans. Methods: This research was conducted in the Marine Biology Laboratory, Faculty of Marine Science and Fisheries, Hasanuddin University, and Division of Fisheries Science, University of Miyazaki. Morphometric character measurements were based on holotype character data, while genetic analysis was performed on cytochrome oxidase subunit I (COI) sequence data. Morphometric data were analysed using principal component analysis (PCA) statistical tests in MINITAB, and genetic data were analysed in MEGA 6. Results: Statistical test results based on morphometric characters revealed groupings largely representative of the Indian and Pacific Oceans. The Seychelles was separated from other Indian Ocean sites and Australian populations were closer to the Pacific than the Indian Ocean group. The genetic distance between the groups was in the low category (0.000 - 0.042). The phylogenetic topology reconstruction accorded well with the morphometric character analysis, with two main L. harak clades representing Indian and Pacific Ocean, and Australia in the Pacific Ocean clade. Conclusions: These results indicate that the morphological character size of L. harak from Makassar and the holotype from Saudi Arabia have changed. Genetic distance and phylogeny reconstruction are closely related to low genetic distance.

Morpho- Functional Observations on Ontogenic development of the Renal excretory system in pre to post flexion stages larvae of Himalaya Snow trout Schizothorax plagiostomus (Heckel)

Schizothorax plagiostomus is one of the most important food fish inhabiting the snow-fed tributaries of the Himalayan region. Due to nutritional value, good growth rate, high economic prospects as well as the decline in the natural habitat its commercial production is desired. Keeping in view this fact, during the present investigation by following the artificial breeding and rearing experiments an attempt has been made to understand the morpho-functional development of the renal excretory system in pre to post-flexion stages larvae. The study reveals that all the essential basic structures of the renal excretory system (pronephros) were established before the initiation of external feeding. During the post-flexion stage when the yolk sac was almost reabsorbed and larvae exclusively depend on exogenous feeding the mesonephric tubules were forming and some of them become functional i.e. presence of glomerulus to maintain the internal environment as well as efficient removal of gradually increasing amount of nitrogenous wastes. The presence of lymphoid tissues was suggesting that cell-mediated immune responses develop progressively in the Himalayan snow trout S. plagiostomus larvae.

Efficacy of some synthetic antibiotics on Streptococcus pneumoniae and Proteus mirabilis isolated from fish tanks

Effects of some synthetic antibiotics on Streptococcus pnemoniae and Proteus mirabilis isolated from cultured Clarias gariepinus, an important food fish raised in a concrete tank was carried out to ascertain their remedies on mortalities of the Clarias gariepinus adult fish. Streptococcus pnemoniae and Proteus mirabilis were isolated from the gill and skin of diseased fish and water samples and identified by standard microbiological methods.The bacteria isolates were tested for sensitivity on ten (10) antibiotics namely Amoxycillin, Gentamicin, Nitrofurantoin, Erythromycine, Augmentin, Tetracycline, Naladoxic acid, Cotrimoxazole, Cloxacillin and Ofloxacin. These organisms reacted differently to the different antibiotics that were used - Ofloxacine, Gentamycin and Erythromycine had highest zones of inhibition of 26mm and 26mm, 24mm and 19mm, 16mm and 17mm respectively around Streptococcus pnemoniae and Proteus mirabilis, but Naladoxic acid, Augmentin, Cloxacillin and Amoxycillin had no inhibition zones around both organisms. It is therefore recommended that Ofloxacine, Gentamycin and Erythromycine can be used to combat S. pnemoniae and P. mirabilis diseases in fish farms because of their high antibacterial potentials against the test organisms.

Modelling and forecasting of catfish species yield from Mangochi artisan fisheries of lake Malawi in Malawi

Most of the wild fish stocks in Malawi either are fully or over exploited. This challenge underpins importance of forecasting using available data to support sustainable fisheries management. The study aimed at modelling and forecasting Catfish (Mlamba) species yield from artisan fishery on Lake Malawi in Mangochi District as they are becoming important food fish due to decline of more important fish species such as Oreochromis(Chambo). The study was based on secondary data on fish catches between1976 and 2012, collected from Fisheries Research Unit of the Department of Fisheries in Malawi. The study considered Autoregressive Integrated Moving Average (ARIMA) processes to select an appropriate stochastic model for forecasting the species yield. Appropriate models were chosen based on ARIMA (p, d, q). Autocorrelation function (ACF), Partial autocorrelation (PACF), Akaike Information Criteria (AIC), Box-Ljung statistics, correlogram of residual errors, distribution of residual errors, ME, RMSE, MAPE and MAE. Selected model was ARIMA (0, 0, 1) for forecasting artisan landings of Catfish from Lake Malawi in Mangochi District from 2013 to 2022. Based on the chosen model, forecast for artisan Catfish landings showed mean of 352 tonnes and mean of actual catches was 362 tonnes. However, catches in year 2022 are projected to be 360 tonnes, slightly below the actual catches mean but above 236 tonnes in 2010, assuming other factors remain constant. Confidence intervals of the forecasts included a zero and as such over exploitation of the species cannot be ruled out. Landings of the fishery will increase to 360 tonnes and remain stable through year 2022 necessitating fisheries management consideration to improve the trend. Policy makers should secure sustainable exploitation of Catfish species, among artisan fishery in the study area by controlling all fishing effort that lands the species such as gillnets, beach seines, open water seines among others.

Biology and Ecology of Grass Carp in China: A Review and Synthesis

AbstractGrass CarpCtenopharyngodon idellawas introduced to the southern United States in the 1960s to control aquatic macrophytes in aquaculture ponds. The accidental release of Grass Carp from some research facilities and aquaculture farms at the start of the introduction, followed by the broad promotion of stocking triploid and diploid fish, helped to facilitate the expansion of the invasive range of the species in North America. Grass Carp have recently been observed to reproduce in Lake Erie. The species has been an important food fish in China for centuries, and Chinese scientists and government agencies have accumulated a great deal of experience, knowledge, and data on Grass Carp. We review Chinese literature and provide a synthesis of the biology and ecology of Grass Carp in China, including the native geographic distribution as well as the factors that determine its reproductive success, growth, and foraging behavior. We also review the impacts of the introduction (or invasion) of Grass Carp on receiving systems and the effects of dams and pollution on Grass Carp. This review fills knowledge gaps in the Western scientific literature about Grass Carp. It provides scientific information that could be used to guide future research and management on ways to control the invasion and propagation of this species.

Perspectives on sustainable management of the Poso Lake (Indonesia) endemic ricefish, Oryzias nigrimas (Actinopterygii: Adrianichthyidae)

Introduction: The endemic fishes of the ancient lakes of Sulawesi are under increasing threat. Objective: To evaluate the data and information available from a holistic management perspective and to formulate measures to conserve the endemic ricefish Oryzias nigrimas in Poso Lake, Indonesia. Methods: Collection of primary data from three stations around Lake Poso and literature study. Results: Threats to O. nigrimas include habitat degradation and loss, introduced alien species, and exploitation as a locally important food fish. Options to promote sustainable fisheries management include spatial and temporal limitations to minimise catch of gravid or brooding fish. Habitat protection should include measures to minimise impacts from activities which can reduce water quality and disturb or kill aquatic vegetation. Conclusion: Measures to prevent further O. nigrimas population decline are considered urgent and further research is recommended to fill identified knowledge gaps. Ex-situ conservation, including the development of captive breeding, could also contribute to a holistic O. nigrimas conservation strategy.

Intraspecific phenotype variations in olive barb Systomus sarana (Hamilton, 1822) population from different rivers is possibly linked to locomotive adaptations in caudal fin

Systomus sarana (Hamilton, 1822) [D1] is an economically important food fish species occurring throughout Indian rivers, which also has ornamental value. This study focused on morphological variations in S. sarana from five river basins across India, viz., Godavari, Mahanadi, Krishna, Middle Ganga and Lower Ganga. A truss network was constructed by interconnecting 12 landmarks to generate 65 morphometric variables extracted from digital images of specimens sampled from the study locations. Transformed truss measurements were subjected to Principal component analysis (PCA), Canonical discriminant function analysis (CDFA), Box plot and Thin plate spline (TPS) analyses. PCA identified eight truss variables with significant loadings, while CDFA designated two truss variables with potential for explaining discrimination between populations. Anterior attachment of dorsal membrane from caudal fin was identified to be the most important variable that presented variations across the river basins studied. Discriminant analysis correctly classified 70.5% of the specimens into their original populations. Thin plate spline for morphometric shape variation analysis indicated highest specimen-shape variations (warping) in Mahanadi basin. TPS-principal strain ratio on principal components (PC-1, PC-2) further revealed significant divergence among the populations in five river basins studied. Results of the study revealed variation in stocks of the species, on the basis of shape morphometry. The four significant parameters, differentiating specimens from different basins, were linked to caudal fin origin at dorsal side and the centre and possibly indicate plasticity in response to locomotive adaptations.

Study of Various Ecological Aspects on Digenetic Trematode Parasites in Important Food Fish Rita rita (Ham.) from Lucknow (India)

Fish fauna is an important component of fresh water ecosystem and considered as gold of water due to their high nutritional and economical value. However, high water pollution and disruption in water ecosystem causes parasite infections in fishes. Fishes bear heaviest burden of helminth parasites because these parasites use the fish for their shelter and food. Digeneans trematodes are important group of parasites which complete their life cycles in vertebrate and invertebrate host. Since, fishes are the important constituent of human food, these parasites readily passed to the human and causes various diseases. Therefore, it is very important to study the impact of various seasonal variations such as temperature, relative humidity and time-period on prevalence, mean intensity and relative density of trematode parasites infection in fishes. In this paper, we have systematically studied all these seasonal variations on the trematode parasites infection in common food fish Rita rita (Ham.) from January, 2009 to December, 2009 in Lucknow region of Uttar Pradesh. Our results suggest that the highest prevalence, mean intensity and relative density of trematode parasites infection occurred in summer season followed by rainy and winter season.

Infection and molecular identification of ascaridoid nematodes from the important marine food fish Japanese threadfin bream Nemipterus japonicus (Bloch) (Perciformes: Nemipteridae) in China.

The Japanese threadfin bream N. japonicus (Bloch) (Perciformes: Nemipteridae) is an important marine food fish in Asia. However, our present knowledge of the occurrence of its nematode parasites is still limited. In the present study, the species composition and infection rate of ascaridoid nematodes in N. japonicus from the South China Sea, were studied for the first time. Five ascaridoid species, namely Anisakis typica (L3), Hysterothylacium amoyense (L3), Hysterothylacium sp. IV-A (L3), adult of H. thalassini and Raphidascaris lophii (L3), were identified using integrative taxonomy. Hysterothylacium amoyense was the most prevalent species (prevalence 47.2%, mean intensity 14.9±17.1). Hysterothylacium thalassini and R. lophii were reported in the Japanese threadfin bream for the first time. Two different genotypes of A. typica (overall prevalence of 3.4%; mean intensity 1.7±0.9) were found in the South China Sea for the first time. The unique restriction polymorphism patterns of three species of Hysterothylacium are provided for rapid diagnosis. Our present results indicate that RFLP analysis of ITS region, using the restriction enzymes HhaI and RsaI, represents a simple and practical method for large-scale surveys of Hysterothylacium for seafood industry.

Skin transcriptome, tissue distribution of mucin genes and discovery of simple sequence repeats in crucian carp (Carassius auratus).

Crucian carp (Carassius auratus) is one of the major freshwater species and important food fish in China. Fish skin acts as the first line of defence against pathogens, yet its molecular and immune mechanism remains unclear. In this study, a de novo transcriptome assembly of C. auratus skin was performed with the Illumina Hiseq 2000 platform. A total of 49,154,776 clean reads were assembled, among which 60,824 (46.86%), 37,103 (28.59%), 43,269 (33.33%) unigenes were annotated against National Center for Biotechnology Information, Gene Onotology and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases, respectively. KEGG Orthology categories were significantly involved in immune system (20.50%), signal transduction (18.04%) and mucosal mucin genes (e.g., muc2, muc5AC, muc5B, muc17, muc18). The high expression of muc18 gene was observed in brain; that of muc2 in intestine; and that of muc5AC in skin, liver, spleen, intestine and muscle. Moreover, the potential 28,928 simple sequence repeats with the three most abundant dinucleotide repeat motifs (AC/GT, AG/CT, AT/AT) were detected in C. auratus. To authors' knowledge, this is the first report to describe the transcriptome analysis of C. auratus skin, and the outcome of this study contributed to the understanding of mucosal immune response of the skin and molecular markers in cyprinid species.

Description of myxosporeans (Cnidaria: Myxozoa) infecting the popular food fish Notopterus notopterus (Pisces: Notopteridae) in Malaysia and India

This study was a co-operative investigation of myxosporean infections of Notopterus notopterus, the bronze featherback, which is a popular food fish in the South Asian region. We examined fish from Lake Kenyir, Malaysia and the River Ganga, Hastinapur, Uttar Pradesh, India, and observed infections with two myxosporeans: Myxidium cf. notopterum (Myxidiidae) and Henneguya ganapatiae (Myxobolidae), respectively. These species were identified by myxospore morphology, morphometry and host tissue affinity, and the original descriptions supplemented with small-subunit ribosomal DNA sequences and phylogenetic analysis. Free myxospores of M. cf. notopterum were found in the gallbladder, and measured 14.7 ± 0.6 μm long and 6.3 ± 0.6 μm wide; host, tissue and myxospore dimensions overlapped with the type, but differed in morphological details (spore shape, valve cell ridges) and locality (Malaysia versus India). Plasmodia and spores of H. ganapatiae were observed in gills, and myxospores had a spore body 9.7 ± 0.4 μm long, 4.5 ± 0.5 μm wide; sample locality, host, tissue, spore morphology and morphometry matched the original description. Small-subunit ribosomal DNA sequences were deposited in GenBank (M. cf. notopterum MT365527, H. ganapatiae MT365528) and both differed by >7% from congeneric species. Although the pathogenicity and clinical manifestation of myxozoan in humans are poorly understood, consumption of raw fish meat with myxozoan infection was reported to be associated with diarrhea. Identification of current parasite fauna from N. notopterus is an essential first step in assessing pathogen risks to stocks of this important food fish.

Effect of sex on hematology, morphology and blood cell characteristics of Schizothorax niger

Study of hematological parameters, blood cell morphology and its characteristics are considered as essential tools to evaluate the health status of fish species. Among snow trout species, Schizothorax niger contribute a significant proportion to the overall fish production in the region, thus considered as an important food fish species. However, the population of this fish species is declining day by day from the natural habitats due to one or another reason. For understanding the health status of the fish an attempt has been made to establish sex wise base line data on hematological parameters, blood cell morphology and its characteristics. Ninety four healthy specimens of S. niger were randomly selected for this study; 48 adult males with an average body length 32.23 ± 1.79 cm; body weight of 290.0 ± 1.79 g, while 46 adult females with average body length 31.8 ± 0.10 cm and body weight 289.0 ± 0.34 g. The hemoglobin and packed cell volume were determined by using cyanmethemoglobin and microhaematocrit method respectively, while total red blood cell and total white blood cell counts were obtained by Neubauer hemocytometer. The blood cell morphological structures and different cell count were studied by using Wright-Giemsa stained blood smears. Erythrocytes, leucocytes (neutrophils, eosinophils, basophils, lymphocytes and monocytes), thrombocytes were distinguished and characterized under light microscopy. The results showed that Hb concentration, total RBC count, Hct value and neutrophils in males were significantly (P 0.05) differences were observed in other hematological parameters and blood cell morphology between male and female S. niger. Hence the data generated in the present study would be useful in monitoring health status of fish.

Morphological and genetic evaluation of the thumbprint emperor, Lethrinus harak (Forsskål, 1775) in the Pacific and Indian Oceans

Background: The Lethrinidae (emperors) include many important food fish species. Accurate determination of species and stocks is important for fisheries management. The taxonomy of the genus Lethrinus is problematic, for example with regards to the identification of the thumbprint emperor Lethrinus harak. Little research has been done on L. harak diversity in the Pacific and Indian Oceans. This study aimed to evaluate the morphometric and genetic characters of the thumbprint emperor, L. harak (Forsskål, 1775) in the Pacific and Indian Oceans. Methods: This research was conducted in the Marine Biology Laboratory, Faculty of Marine Science and Fisheries, Hasanuddin University, and Division of Fisheries Science, University of Miyazaki. Morphometric character measurements were based on holotype character data, while genetic analysis was performed on cytochrome oxidase subunit I (COI) sequence data. Morphometric data were analysed using principal component analysis (PCA) statistical tests in MINITAB, and genetic data were analysed in MEGA 6. Results: Statistical test results based on morphometric characters revealed groupings largely representative of the Indian and Pacific Oceans. The Seychelles was separated from other Indian Ocean sites and Australian populations were closer to the Pacific than the Indian Ocean group. The genetic distance between the groups was in the low category (0.000 - 0.042). The phylogenetic topology reconstruction accorded well with the morphometric character analysis, with two main L. harak clades representing Indian and Pacific Ocean, and Australia in the Pacific Ocean clade. Conclusions: These results indicate that the morphological character size of L. harak from Makassar and the holotype from Saudi Arabia have changed. Genetic distance and phylogeny reconstruction are closely related to low genetic distance.

Growth and gonadal development of female Nile tilapia (Oreochromis niloticus) exposed to sex reversing thermal treatment

Nile tilapia is globally one of the most important food fish in aquaculture. It is a gonochoric species showing an enormous plasticity in sex determination. In response to exposure of genetic female fry to elevated water temperature between 10 and 20 days post hatching, corresponding to 14 to 24 days post fertilization (dpf), 37% were masculinized. Of control fry not exposed to thermal treatment all fish were females. Little is known about the dynamics of gonadal development in females that were thermally treated without getting masculinized. The present study addresses this question and investigates the effect of thermally induced sex conversion on overall growth rate. Beginning 90 dpf and until 240 dpf every 30 days 6 fish were sacrificed to assess growth and gonadal dynamics. Growth rate was highest in masculinized fish; the gonado-somatic-index (GSI) was higher in females, indicating development toward female gonads. Macro- and micromorphological study of the ovaries at various stages of development revealed that there was no difference in ovarian dynamics between temperature-treated and control females. In the present study temperature-induced masculinization was effective in more than one third of genetic females in conjunction with a 45% increase in body mass at close to 8 months of age, without affecting ovarian dynamics in non-masculinized females. The latter may provide for successful production of progeny, while the former may positively impact feeding the world.

Study on Biometric Parameters and Genetic Diversity of Labeo rohita from Harike Wetland-A Ramsar Site

Background: Harike wetland (31°08¢ N to 31°23¢ N latitudes and 74°90¢ E to 75°12¢ E longitudes) is an internationally important Ramsar site, supports rare, vulnerable and endangered plants, fish and other faunal species. Weed infestation, pollution and encroachment are considered as important threats of its biota thus time series data with respect to fish diversity, catch composition and genetic variability has an utter importance to interpret changes over time. Cyprinidae family of freshwater fishes includes carps is the largest fish family found in Harike wetland comprising around 50% of total fish composition by weight basis and among carps, Rohu (Labeo rohita) is one of the commercially important food fish species available throughout the year and preferred by consumers. As river Beas and Sutlej, two major rivers of Indus river system confluence at Harike thus possibility of variation within fish stock is very high. With this background present study was carried out to evaluate the fish biodiversity and catch composition of Harike wetland. Study also emphasized on biometrics, length –weight relationship and genetic diversity based on mitochondrial marker genes of commercially important food fish Labeo rohita. Methods: Assessment of fish catch composition and diversity were conducted in landing centre adjacent to Harike wetland through Rapid Fisheries Assessment by Market Survey (RFAMS) technique. Fin tissue samples were collected for genetic diversity analysis of L. rohita by cytochrome oxidase subunit I (COI) gene sequencing, From the fish genomic DNA a partial fragment of approximately 655bp was PCR amplified by FishF1 (5'-TCAACCAACCACAAAGACATTGGCAC-3') and FishR1 (5'-TCGACTAATCATAAAGATATCGGC AC-3') primer pair. Calculation of intraspecific mean and pairwise distances was performed by MEGA 6.0 software using the K2P parameters Results: Total 30 species of fishes were recorded from Harike wetland and these belong to 14 families and 21 genera. In L. rohita average weight (Wt), total length (TL), standard length (SL) and forked length (FL) were recorded 2600±5.64g (1700-3600 g), 58.2±5.65 cm (51.3-67.6cm), 48.0±8.54 cm (42.5-55.5cm) and 46.0±0.25 cm (38.0-54.5cm), respectively. Biometric study revealed that sufficient numbers of mature L. rohita are available in wetland. L. rohita established negative algometric growth (b= 2.701); thus species became slender as it increased in length. The pairwise distances ranged from 0.00 to 18.49% with a mean ±S.E value of 4.70%±0.40. Total of 9 haplotypes were observed in L. rohita COI sequences. The diversity in haplotype and nucletide values were observed 0.848 and 0.024, respectively. The present study states that L. rohita stocks in Harike wetland are genetically diverse.