Silver Barb Research Articles

Dietary fish oil replacement by linseed oil: Effect on growth, nutrient utilization, tissue fatty acid composition and desaturase gene expression in silver barb (Puntius gonionotus) fingerlings.

Silver barb (Puntius gonionotus) is considered a promising medium carp species for freshwater aquaculture in Asia. This study in silver barb was carried out to evaluate the effects of total or partial substitution of dietary fish oil (FO) with linseed oil (LO) on growth, nutrient utilization, whole-body composition, muscle and liver fatty acid composition. Fish (12.1±0.4g of initial body weight) were fed for 60days with five experimental iso-proteinous, iso-lipidic and iso-caloric diets in which FO (control diet) was replaced by 33.3%, 50%, 66.7% and 100% LO. Final weight, weight gain, percent weight gain, SGR decreased linearly (p<0.001) with increasing LO levels in the diets. Dietary LO substitution levels did not significantly (p>0.05) affect the feed conversion ratio (FCR), protein efficiency ratio (PER) and whole body proximate composition. Furthermore, enhanced level of LO increased α-linolenic acid (ALA; 18:3n3) and linoleic acid (LA; 18:2n6) and decreased eicosapentaenoic acid (EPA; 20:5n3) and docosahexaenoic acid (DHA; 22:6n3) in muscle and liver. To understand the molecular mechanism of long chain-polyunsaturated fatty acid (LC-PUFA) biosynthesis, we cloned and characterized the fatty acyl Δ6 desaturase (Δ6 fad) cDNA and investigated its expression in various organs/tissues following replacement of FO with LO in the diet. The full-length Δ6 fad cDNA was 2056bp encoding 444 amino acids and was widely expressed in various organs/tissues. Replacement of FO with LO increased the expression of Δ6 fad mRNA in liver, muscle and intestine but no significant difference was found in the brain.

Acute exposure to a quinalphos containing insecticide (convoy) causes genetic damage and nuclear changes in peripheral erythrocytes of silver barb, Barbonymus gonionotus

The present study was aimed to assess the genotoxic effect in fish caused by convoy, an insecticide commercial formulation containing quinalphos, present in the aquatic waterbody. For this purpose a freshwater teleost, silver barb was exposed to sublethal concentrations (25% and 50% of LC50) of convoy and erythrocytic cellular abnormalities (ECA) and erythrocytic nuclear abnormalities (ENA) tests were performed in addition to the commonly used micronucleus (MN) assay using peripheral erythrocytes and DNA contents in the different tissues after 1, 24, 36, 48, and 72 h of exposures. The obtained results indicated that acute exposure of different sub lethal concentrations of convoy to the fish resulted in significant alterations of erythrocytes as well as significant reduction of DNA contents in blood and vital organs and tissues, such as the brain, liver, kidney and muscle. Compared to each treatment excluding control group, frequencies of ECA, ENA, and MN were found to be elevated with exposure time of the doses. From this study, we conclude that convoy is a hazardous chemical to silver barb. Bioassays can be used as a tool for screening aquatic pollution, especially for insecticides.

Influence of Aeromonas hydrophila and Pseudomonas fluorescens on motility, viability and morphometry of cryostored silver barb (Barbodes gonionotus) sperm

This objective of the study was to evaluate the effects of A. hydrophila subsp. hydrophila and P. fluorescens on sperm motility, sperm viability and sperm morphometry of cryopreserved silver barb (Barbodes gonionotus) semen and survival of tested bacteria after cryostorage. Semen was diluted in a calcium-free Hank's balanced salt solution (Ca-F HBSS) supplemented with or without 0.25% penicillin-streptomycin (PS) after which A. hydrophila subsp. hydrophila or P. fluorescens was immediately added into extended semen prior to freezing. Extended semen and cryostored semen kept for 20 min, 24 h, 7 d, 14 d and 28 d were assessed for sperm motility, sperm viability, sperm morphometry, survival of challenged bacteria and the relationship between bacteria and sperm. Bacterial-exposed semen with or without 0.25% PS supplementation showed a significant reduction (P < 0.05) in sperm motility and viability during a cryostorage of 28 d, compared to semen without bacterial supplementation (control groups). Addition of A. hydrophila subsp. hydrophila and P. fluorescens resulted in a significant (P < 0.05) alteration of sperm morphometry of cryopreserved semen, especially flagellum width. The two pathogens were detected at a level of 105 CFU ml−1 in cryostored semen with or without antibiotic supplementation. There were significant correlations among bacterial number, percentage of sperm motility and viability and flagellum width. In conclusion, the presence of A. hydrophila subsp. hydrophila and P. fluorescens had a deleterious effect on cryopreserved silver barb sperm based on a reduction in sperm motility and viability and alteration of sperm morphometry, especially flagellum width.

Diversity of Fish and Mapping Distribution of Invasive, Banned and Protected Fish at Rawadanau Concervation Area Banten

Rawadanau Conservation Area has main function to take care of biodiversity. The research of fish diversity and Invasive Alien Species has been conducted. The research was conducted in August-September 2015. The aim is to show the value of community structures such as index of fish diversities, the similarities, dominances and alien species. We found nine species contain 198 fish, the details are 63 fish at Muara station, 73 fish at Jamungkal and 62 at Cibungur. The category of Biodiversity index showed low category, as follows 1.7306, 1.1146 and 1.2153. The category of similarity index showed low-middle category between 0.259786 – 0.417703. The details are 0.417703 at Muara Station (middle category and labil community); 0.259786 at Jamungkal Station and 0.294471 at Cibungur Station (Low Category and depressed community), dominancy index is in low category between 0.268-0.353, it is 0.268 at Muara Station, 0.353 at Jamungkal Station and 0.320 at Cibungur Station. The endemic fish are spotted gouramy, common snakehead, climbing gouramy, gondang snail and silver barb fish. Alien species are plecos, pomfret, carp and catfish. The water temperature 26-27 oC, pH between 5.76-6.16,water depth 150 s/d >200 m, brightness 53.3- 66.6 m, current speed 0.12-0.15 (m/s), DO 6-6.3 mg/l and bog sediment.

Morphological and morphometric evaluation of silver barb, Barbodes gonionotus (Bleeker, 1849) sperm supplemented with antibiotics

Aim of this study was to evaluate sperm morphology of silver barb, Barbodes gonionotus, sperm and describe the effect of antibiotics on morphological characteristics of the sperm using an ASMA plug-in. The experiment was done at the room temperature (25°C) and divided into four treatments in three replicates: (i) freshly collected semen, (ii) extended semen (control), (iii) extended semen supplemented with 0.5% penicillin-streptomycin (PS), and (iv) extended semen supplemented with 0.5% penicillin-gentamicin (PG). Silver barb sperm comprised three main compartments: a circular head with no acrosome, a midpiece, and a single flagellum. Addition of 0.5% PS had no detrimental effects on sperm morphometry, except flagellum width. Administration of 0.5% PG affected sperm morphology in two distinct ways: (i) intact sperm (76.92 ± 5.84% of total sperm) except for flagellum width, and (ii) severe morphological damage (23.08 ± 2.67%).

Effect of antibiotic supplementation on the quality of cryopreserved fish sperm of silver barb (Barbodes gonionotus): Sperm motility and viability, bacterial quality and fertilization

Disease prevention is a key aspect in developing cryopreservation procedures for fish sperm and in improving the reproductive biotechnology for commercially important aquatic species. The purpose of this study was to evaluate the effects of an antibiotic supplementation (0.25% penicillin–streptomycin, PS and 0.25% penicillin–gentamicin, PG) on sperm motility and viability, bacterial profile and fertilization capacity of cryopreserved silver barb (Barbodes gonionotus) semen. The experimental protocol involved three treatments: addition of PS alone; addition of PG alone; and no addition of antibiotics (Control). Semen samples were frozen and cryostored for 12-mo. Administration of 0.25% PS significantly (P<0.05) improved sperm motility and viability and reduced (P<0.05) total heterotrophic bacteria, Gram negative bacteria and pseudomonads bacteria in cryopreserved semen. Post-thawed semen treated with 0.25% PS did not contain contaminating bacteria including Bacillus subtilis subsp. inaquosorum, Bacillus safensis, Aeromonas punctata subsp. caviae, Serratia plymuthica, Pseudomonas azotoformans and Pseudomonas sp. Post-thawed semen supplemented with 0.25% PG showed degenerative changes in motility and viability of sperm. Eggs fertilized with 0.25% PS or antibiotic-free cryopreserved semen had similar fertilization rates, lower (P<0.05) than those of fresh semen. Incorporation of 0.25% PS was suitable for cryopreservation of silver barb semen based on the presence of good quality of post-thawed sperm and elimination of bacterial contaminants: B. subtilis subsp. inaquosorum, B. safensis, A. punctata subsp. caviae, Ser. plymuthica, P. azotoformans and Pseudomonas sp. This is the first study to investigate the antibiotic effect on the number of bacteria and their profile in cryopreserved semen of fish.

Semen collection methods affect the bacterial composition of post-thawed semen of silver barb (Barbodes gonionotus)

Biosafety issue associated with the risk of pathogenic contamination of cryopreserved semen is a common concern because of associated declines in sperm quality, storage period and disease transmission. This study was conducted to evaluate the effects of methods of semen collection on sperm quality and bacterial composition of post-thawed semen of silver barb (Barbodes gonionotus). Semen collection methods consisted of four treatments: (1) hand-stripping of abdomen without rinsing of urogenital area with water, (2) hand-stripping of abdomen after rinsing of urogenital area with water, (3) catheterization without rinsing of urogenital area with water and (4) catheterization after rinsing of urogenital area with water. Semen diluted with calcium-free Hank's balanced salt solution containing 10% dimethylsulfoxide (DMSO) was frozen at a freezing rate of −8°Cmin−1 before plunging in liquid nitrogen. Post-thawed semen collected by catheterization after rinsing urogenital area had the lowest bacterial number, about 2-log reduction of total heterotrophic, Gram negative and pseudomonad bacteria, compared with the other three collection treatments. However, percentages of motile and viable sperm were not significantly (P>0.05) different among treatments. This method eliminated Flavobacterium aquatile, Bacillus megaterium, Kocuria varians, Staphylococcus haemolyticus and Aeromonas media in cryopreserved semen. This is the first report demonstrating the effects of semen collection methods on bacteriological quality of frozen-thawed fish semen.

Comparison of infectivity, metacercarial burden and host mortality induced by Opisthorchis viverrini sensu lato cercariae from Lao PDR compared with Thailand in cyprinid fish, Barbonymus gonionotus.

Previous studies indicate that Opisthorchis viverrini sensu lato (s.l.) is a species complex with strong associations to geographical regions, i.e., specific wetlands. The present study was conducted to compare the infectivity, establishment and metacercarial burden and survival of the fish host following exposure to O. viverrini s.l. cercariae isolates from two different river wetlands. Experimental infections were performed by exposing fish (silver barb, Barbonymus gonionotus) individually to 0 (control) and 100 O. viverrini s.l. cercariae originating from the Songkram River wetland in Thailand and the Nam Ngum River wetland, Lao PDR. Metacercarial burden and fish survivals were monitored after infection. Fish exposed to O. viverrini s.l. cercariae from the Nam Ngum River wetland had significantly greater metacercarial burden and more active motility at 28 and 35 days post infection than those from the Songkram River wetland. The mortality of fish infected with O. viverrini s.l. from the Nam Ngum River wetland was greater than that from the Songkram River wetland (log-rank test, p<0.01). The findings in this study provided additional evidence supporting the importance of cryptic species of O. viverrini s.l. and it has implications for parasite transmission dynamics, life cycle success and disease ecology.

Susceptibility, metacercarial burden, and mortality of juvenile silver barb, common carp, mrigal, and tilapia following exposure to Haplorchis taichui.

Fish-borne zoonotic trematodes (FZT) including heterophyids and opisthorchiids are prevalent in native and aquaculture fish in Southeast Asia. FZT are reported highly prevalent in juvenile aquaculture fish that belonged to the family Heterophyidae, particularly Haplorchis taichui. Aquaculture fish are reported to have varying levels of natural infection with H. taichui, but data for their susceptibility as well as resistance to infection are not available. The aim of this study was to determine the susceptibility of five aquaculture fish to H. taichui. Experimental infections were performed by exposing fish individually to 0 (control), 50, 100, or 200 H. taichui cercariae for 12 h. Metacercarial burden was measured at 45 days postinfection. Three out of five fish species, silver barb (Barbonymus gonionotus), common carp (Cyprinus carpio), and mrigal (Cirrhinus mrigala), were highly susceptible to H. taichui infection with percentage ranging from 93.33 to 100%. The Nile and red tilapia were not susceptible to infection. Among the susceptible fish species, silver barb had higher intensity of H. taichui metacercariae than common carp and mrigal (P < 0.001). Metacercarial burden significantly correlated with the dose of cercarial infection (P < 0.001). Our findings that common aquaculture fish species have varying degrees of susceptibility to H. taichui infection provide important information to reduce parasite transmission in aquaculture fish.

Alteration of Blood Parameters and Histoarchitecture of Liver and Kidney of Silver Barb after Chronic Exposure to Quinalphos.

Quinalphos (QP) is commonly used for pest control in the agricultural fields surrounding freshwater reservoirs. This study was conducted to evaluate the chronic toxicity of this pesticide on blood parameters and some organs of silver barb, Barbonymus gonionotus. Fish were exposed to two sublethal concentrations, 0.47 ppm and 0.94 ppm, of QP for a period of 28 days. All the blood parameters (red blood cell, hematocrit, and hemoglobin) and blood glucose except for white blood cells decreased with increasing concentration of toxicant and become significantly lower (p < 0.05) at higher concentration when compared with control. The derived hematological indices of mean corpuscular volume, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration were equally altered compared to control. Histoarchitectural changes of liver and kidney were observed after exposure to the QP. Hypertrophy of hepatocytes, mild to severe necrosis, ruptured central vein, and vacuolation were observed in the liver of treated groups. Highly degenerated kidney tubules and hematopoietic tissue, degeneration of renal corpuscle, vacuolization, and necrosis were evident in the kidney of treated groups. In conclusion, chronic exposure to QP at sublethal concentrations induced hematological and histological alterations in silver barb and offers a simple tool to evaluate toxicity derived alterations.

Evaluation of the potential source of bacterial contamination during cryopreservation process of silver barb (Barbodes gonionotus) sperm

Application of good sanitation practice in cryopreservation process is the key issue to improve the quality of cryopreserved fish sperm. This study implemented standard sanitation protocol with minimal contamination and evaluated the source of bacterial contamination associated with laboratory equipment and related materials across a series of cryopreservation process of silver barb (Barbodes gonionotus) semen. The use of 16s rRNA sequencing and traditional biochemical methods were performed for bacterial identification. Animal origin (anal fin, culture water and semen contaminated with faeces and urine) and non-animal origin (liquid nitrogen from liquid nitrogen dewar, outer surface of straw, air circulation in cryopreservation laboratory and latex gloves used during cryopreservation procedure) were determined for bacterial contamination. Aeromonas punctata subsp. caviae was the most abundant species in anal fin, latex groves and semen contaminated with faeces and urine. Bacillus safensis and Bacillus sp. were found as frequently recovered species from liquid nitrogen dewar. Aeromonas hydrophila subsp. hydrophila and Pseudomonas fluorescens, fish pathogenic bacteria, were isolated from all animal origin samples. This was the first report indicating that standard sanitation and hygiene methodologies are recommended for sperm cryopreservation of B. gonionotus to prevent bacterial contamination.

Low-cost mobile hatchery produced silver barb (Barbodes gonionotus) fingerling: it's growth and economic performance in intensive culture system

Low-cost mobile hatchery produced silver barb (Barbodes gonionotus) fingerling: it's growth and economic performance in intensive culture system

Sperm cryopreservation of silver barb (Barbodes gonionotus): cryoprotectants, cooling rate and storage time on sperm quality

Effectiveness and efficiency of frozen sperm on fertilization and hatching success of eggs from silver barb was examined in relation to cryoprotectants, freezing rate and storage period. Sperm was diluted in calcium-free Hank's balanced salt solution, equilibrated with dimethylsulphoxide (DMSO), propylene glycol, sucrose or methanol at 5%, 10%, 15% or 20% final concentrations, and frozen in 250-μL straws using a one-step freezing procedure (1, 5 and 8°C min−1 from 25 to −40°C). Highest post-thaw sperm motility was found from a treatment using 10% DMSO and 5°C min−1 (82.2 ± 2.1%), similar to that of 10% DMSO and 8°C min−1 (87.8 ± 3.2%). Post-thaw motility of sperm frozen at 5 or 8°C min−1 was significantly higher than 1°C min−1. Relative sperm motility declined significantly after 10 months of cryostorage while viability did not change during a 12-month cryostorage. Average fertilization rates of sperm after 1 and 4 months of storage were 64.5 ± 4.6% and 61.3 ± 3.4%, respectively, similar to those of fresh sperm (69.6–72.3%). Hatching rates of cryopreserved sperm (45.4–51.2%) were similar to those of fresh sperm (51.8–57.8%). This study developed suitable methods for cryopreservation of silver barb sperm that can be used to facilitate hatchery operation.

Evaluation of Medicinal Plants Through Fish Feed Against Bacterial Fish Disease

Experiments were conducted maintaining under aquarium and pond conditions using feed containing medicinal plants/extracts was evaluated on artificially and naturally infected fish with bacterial pathogens. When the fish were exposed to high bacterial pathogens Aeromonas hydrophila Ah-11, Pseudomonas fluorescens Pf-13 and Edwardsiella tarda Et-70, recovery of the infected fish varied with the pathogens challenged and feed treatments. Fish feed containing bulb extract of Allium sativum (3% feeding) showed significantly (p&lt;0.01) high therapeutic effect recovering the infected fish (Thai silver barb, Barbodes gonionotus) with A. hydrophila (100 ± 0% recovery) and P. fluorescens (90±0% recovery). A similar result was observed in the case of pangas fish feed containing decoction of leaves of Calotropis gigantea where 100 ± 0% E. tarda infected Thai pangas (Pangasius hypophthalmus) were found to be cured. These two types of herbal feed offered similar result when applied to the naturally ulcer-affected Thai silver barb and Thai pangas fingerling under aquarium condition. In pond condition, the herbal feed containing bulb extract of A. sativum was applied experimentally to A. hydrophila infected different fish species maintained in different individual ponds where, 91.67 ± 2.35% Thai silver barb, 84.99 ± 2.35% Rui (Labeo rohita) and 74.99 ± 2.35% Mrigal (Cirrhinus cirrhosus) were found to be recovered. In contrast, plants mixed pangas feed containing decoction of leaves of C. gigantea was cured 94.44 ± 3.84% E. tarda infected Thai pangas. The other medicinal plants used in this study showed medium to weak effect recovering the bacterial infected fish.DOI: http://dx.doi.org/10.3329/pa.v19i2.16956 Progress. Agric. 19(2): 151 - 159, 2008

Laboratory Investigation on Salinity Tolerance to &lt;i&gt;Barbodes Gonionotus&lt;/i&gt; (Bleeker)

Salinity tolerance to Thai silver barb, Barbodes gonionotus was investigated under laboratory conditions using common salt (NaCl) and sea water. With a view to determine the median lethal concentrations (LC50 values), the fish were exposed to various concentrations of the salt and sea water for a period of 96. Common salt up to a concentration of 12 ppt and sea water up to a concentration of 10 ppt did not cause mortality to the experimental fish. The LC50 values for 6h, 12h, 24h, 48h, 72h, and 96 hexposure times were 17.91 ppt, 16.91 ppt, 15.35 ppt, 14.51 ppt and 13.92 ppt common salt, respectively. During experiment action with sea water, the LC50 values obtained were 15.02 ppt, 14.18 ppt, 13.48 ppt, 12.61 ppt, 12.35 ppt and 12.25 ppt for 6 h, 12 h, 24 h, 48 h, 72 h and 96 h exposure times, respectively, On the other hand, pre-exposure acclimation in modifying the acute lethal toxicity of the salt showed, a concentration of 18 ppt salt killed all the fish within 4 days, indicating that gradual increases in salinity increases the salt tolerance of B. gonionotus.DOI: http://dx.doi.org/10.3329/pa.v20i1-2.16871 Progress. Agric. 20(1 &amp; 2): 193 – 200, 2009

Comparative Performance between Genetically Improved and Traditional Silver Barb Strain: a Bio-Economic Analysis

Bangladesh Fisheries Research Institute (BFRI) has developed an improved namely, strain silver barb which shows superior performance in terms of growth and production in on-station condition. This paper analyses the comparative performance of improved silver barb strain on an average as well as on an efficient farm. Ordinary least squares regression and tobit models are estimated on an average weight at harvest and the survival rate, respectively to assess the comparative performance of the improved silver barb strain on an average farm. Stochastic frontier functions for weight at harvest are also estimated to assess the comparative performance of the improved strain on an efficient farm. The result shows a superior performance of the genetically improved silver barb strain compared to traditional strain on both average and efficient farms. On an average farm, the improved silver barb strain gives 25% higher body weight at harvest. The breakeven price above variable cost is 4.71% lower for the improved strain. The result shows that the improved silver barb strain has higher potential yield and average yield than the traditional strain.DOI: http://dx.doi.org/10.3329/pa.v23i1-2.16577Progress. Agric. 23(1 &amp; 2): 133 – 142, 2012

Performance of different fish species for controlling weeds in rainfed lowland rice field

A field experiment was conducted during wet season to evaluate the performance of different fish species for biocontrol of weeds in rainfed waterlogged rice fields with fingerlings of three exotic carps – grass carp, Ctenopharyngodon idella (Val.) (Cyprinidae, Cypriniformes), silver barb, Puntius gonionotus (Bleeker) (Cyprinidae, Cypriniformes) and common carp, Cyprinus carpio (L.) (Cyprinidae, Cypriniformes) – and three Indian major carps – rohu, Labeo rohita (Ham.) (Cyprinidae, Cypriniformes), catla, Catla catla (Ham.) (Cyprinidae, Cypriniformes), mrigal, Cirrhinus mrigala (Ham.) (Cyprinidae, Cypriniformes). A total of 13 major weeds under the categories of grassy, sedges, broadleaf and aquatic weeds were observed in the rice fields. Grass carp reduced maximum weed biomass (weed control efficiency [WCE] 63% at 60 days after transplanting [DAT] and 62% at 100 DAT) followed by silver barb and common carp. Among the Indian carps, only rohu was effective in control of weeds (WCE, 23% at 60 DAT). The grain yield of rice (variety Varshadhan) slightly increased (4.2–4.5 t/ha), but straw yield was significantly higher (10.2–10.7 t/ha) under rice-fish farming. Fish yield was significantly higher in exotic carps (270–288 kg/ha/90days) due to higher specific growth rates (1.8–2% body weight/day). The study indicated that exotic carps (grass carp, silver barb and common carp in order) were more effective than Indian carps for control of weed in rainfed lowland rice fields and among the Indian carps, rohu showed potential for weed control.

Identification of novel and zoonotic Cryptosporidium species in fish from Papua New Guinea

There is still limited information on the distribution of Cryptosporidium species and genotypes in fish. The present study investigated the prevalence of Cryptosporidium species in cultured freshwater (n=132), wild freshwater (n=206) and wild marine (n=276) fish in Papua New Guinea (PNG) by PCR screening at the 18S rRNA locus. A total of seven fish (2 cultured freshwater, 1 wild freshwater and 4 wild marine fish) were identified as positive for Cryptosporidium. Specifically, Cryptosporidium was found in four different host species (Nile tilapia, Oreochromis niloticus; silver barb, Puntius gonionotus; mackerel scad, Decapterus maracellus and oblong silver biddy, Gerres oblongus), giving an overall prevalence of 1.14% (95% CI: 0.3–2%, n=7/614). Of the seven positive isolates, five were identified as C. parvum and two were a novel piscine genotype, which we have named piscine genotype 8. Piscine genotype 8 was identified in two marine oblong silver biddies and exhibited 4.3% genetic distance from piscine genotype 3 at the 18S locus. Further subtyping of C. parvum isolates at the 60kDa glycoprotein (gp60) locus identified 3 C. parvum subtypes (IIaA14G2R1, IIaA15G2R1 and IIaA19G4R1) all of which are zoonotic and a C. hominis subtype (IdA15G1). The zoonotic Cryptosporidium were identified in fish samples from all three groups; cultured and wild freshwater and wild marine fish. Detection of Cryptosporidium among aquaculture fingerlings warrants further research to gain a better understanding of the epidemiology of Cryptosporidium infection in cultured fish. The identification of zoonotic Cryptosporidium genotypes in fish from PNG has important public health implications and should be investigated further.

Use of low-cost chemotherapeutic and medicinal plants against Thai silver barb (Barbonymus gonionotus)

Studies were conducted to select and apply the effective low-cost chemotherapeutic and medicinal plants against diseased fish under laboratory and field condition. Thai silver barbs (Barbonymus gonionotus) weighing 20-25 gm were experimentally infected with a virulent bacterial pathogen (Aeromonas hydrophila) and a fungal pathogen (Aphanomyces invadans). Based on the previous studies, four chemotherapeutics, viz., salt + lime, alum, doxycycline and oxytetracycline were selected and applied to observe the therapeutic effects under laboratory and field condition. In the case of medicinal plants, leaves/ bulb / seeds/ rhizome of neem (Azadirachta indica), akand (Calotropis gigantea), garlic (Allium sativum), turmeric (Curcuma longa), shoti (Curcuma zedoaria), Indian sorrel (Oxalis corniculata), guava (Psidum guajava) and kalijira (Nigella sativa) were screened out and applied to the infected fish in laboratory and field condition to determine their efficacies. The antibiotics, both oxytetracycline and doxycycline were found to be very efficient followed by salt + lime and alum. For fungal infection, alum was excellent followed by salt + lime both under laboratory and field condition. Even in the pond trial, alum and salt + lime successfully checked the occurrence of epizootic ulcerative syndrome (EUS) and similar diseases. In the case of medicinal plants, neem and akand together reduced the occurrence bacterial and fungal disease. Garlic was very efficient to check bacterial infection but weak against fungal disease. Turmeric and arrowroot were found to be highly effective against fungal disease but moderately effective against bacterial disease. Field trial revealed that Indian sorrel and guava were highly efficient against bacterial disease but poorly efficient against fungal disease. On the other hand, arrowroot and black cumin were highly efficient against fungal disease but moderately efficient against bacterial disease. The results would be useful to the all concerned for proper health management of cultured fishes.DOI: http://dx.doi.org/10.3329/jbau.v10i2.14932 J. Bangladesh Agril. Univ. 10(2): 385-390, 2012

A Cross-Sectional Study on the Potential Transmission of the Carcinogenic Liver Fluke Opisthorchis viverrini and Other Fishborne Zoonotic Trematodes by Aquaculture Fish

Throughout Southeast Asia and China, eating raw and or partially cooked cyprinid fish causes liver (hepatobiliary) disease and cancer (cholangiocarcinoma) due to fishborne zoonotic trematodes (FZT), in particular Clonorchis sinensis and Opisthorchis viverrini. The primary source of transmission is by native fish, but aquaculture fish are also reported to have high infective potential. Here, a cross-sectional survey of FZT in fish farms was conducted in an endemic area in Khon Kaen Province, Thailand. By using conventional and polymerase chain reaction (PCR) methods, we detected O. viverrini and FZT metacercariae (Centrocestus formosanus and Haplorchis taichui) in two popular fish species, Barbonymus gonionotus (silver barb) and Cirrhinus mrigala (mrigal), from aquaculture farms. Both species were infected in five of six farms examined by PCR but not by conventional methods, yet the prevalence of FZT metacercariae in aquaculture fish was high (46.9%). In addition to O. viverrini (17.1%), the native fish Cyclocheilichthys armatus and Hampala dispar had a prevalence of FZT of 81.4%, which included 5.7% for C. formosanus and 17.1% for H. taichui by conventional method. To our knowledge, this is the first discovery of O. viverrini in aquaculture fish in Thailand. More comprehensive studies are required to determine if human-induced disease transmission coupled with natural transmission cycle occurs throughout the aquaculture industry in the region. This has significant impact on food quality and safety, and provides the basis for the development of an effective strategy for the prevention and control of foodborne diseases.