Polychaetes (Perinereis sp.) have been used extensively in shrimp broodstock maturation diets because of their nutritional value, being rich in protein, fat and minerals. The aims of this study were to identify the reproduction-related gene in polychaetes, and analyze gene expression levels in polychaetes. Messenger RNA (mRNA) was isolated from mature polychaete samples and used as the template for complementary DNA (cDNA) synthesis. The cDNAwas then subjected to cloning and sequencing. However, no cDNA sequence was found to match the reproductive-related gene. As an alternative procedure, a set of cDNA was synthesized and sequenced by the pyrosequencing method. From 454 Pyrosequencing, 40,402 raw sequences were obtained, covering 14,747,824 nucleotides 200-300 bp inlength andgrouped into 609 isotigs, 712 contigs and 15,975 singletons. In addition, BLASTX analysis showed that 410 sequences (67.3%) matched known genes, whereas, 199 sequences (32.7%) showed no significant homology to known genes. A significant match was found with the vitellogenin structural genes' (yolk protein genes) family member (vit-1)-like gene, which was grouped as the reproduction-related gene in polychaetes. The gene was then used to analyze the expression levels inpolychaetes aged 2, 3, 4, 5, 6, 7, and 8 months by real-time quantitative RT-PCR. The highest vitellogenin gene expression was found in6 -month old polychaetes (P<0.05) and dramatically decreased after reaching 6 months. This result suggested that 6 -month old polychaetes will be suitable as the maturation diet for shrimp broodstock; however, the effect on shrimp reproductive development may need to be analyzed further.
This study considers the variation of catch methods of wrasses for taxonomic study. Since most wrasses live in coral reefs, non-destructive methods are preferred. Four methods of a small spear gun, gill net, scoop net and baited hook were used to collect the fish samples. The gill net was the most successful capture method in terms of specimens and number of individuals caught, followed by the scoop net, baited hook and small spear gun. Given the diversity of sizes caught, the catch was divided into small (4-10cm), medium (11-20 cm) and large (21-100 cm) sizes. The gill net proved to be the most successful capture method for all sizes, while the small spear gun and baited hook were successful only for medium and large fish, respectively. However, the scoop net was suitable for the capture of small and medium sized wrasses, although the quantity and diverity were less than the gill net. Wrasses are usually solitary or occur in pairs, but some form small schools, particularly in the juvenile phase. Accordingly, this study also divided the species caught into those that were solitary or in pairs, and schooling. Again, the gill net proved to be the most successful catch method, following by the scoop net, baited hook and small spear gun. The gill net is suitable equipment for both solitary and schooling wrasses, while the baited hook is effective only for solitary fish.
Themortality rate and histopathology of unilaterally ablated female Pacific white shrimp (Litopenaeus vannamei) broodstock from six commercial hatcheries in Thailand were studied. Hatcheries A, B, and C used shrimp broodstock that were domesticated in Thailand. These shrimp were reared in earthen ponds without proper biosecurity systems. Meanwhile, hatcheries D, E, and F imported shrimp broodstock from the United States of America (USA) and reared them in closed recycling facilities with biosecurity systems in order to investigate the health of shrimp broodstock used inthe Thai shrimp industry. The mortality rate was monitored for two months, and 10 female broodstock with similar lengths (18-21 cm) from each hatchery were sampled for histopathological studies of the hepatopancreas and lymphoid organ. The results revealed that the mortality rate of shrimp domesticated in Thailand was 43.47±9.51%, significantly higher (P>0.05) than that of the imported group, which was 5.93±1.93%. The histopathology of the hepatopancreas revealed that no differences existed in the appearance of the lipid cells in the hepatopancreas of the broodstock from the two studied groups. The number of lipid cells inthe shrimp hepatopancreas ranged from 77 to 93%. For the lymphoid organ, a significant difference (P<0.05) was found between the number of spheroids in the lymphoid organ of the shrimp in the group that was domesticated in Thailand (42.00±18.83%) and in the imported group (0.17±0.91%). We suspect that the presence of numerous spheroids in the lymphoid organ of the shrimp in the domesticated group is probably related to the contamination of the infectious antigens during grow out since these shrimp were cultured in earthen ponds without proper biosecurity systems. The practice of only stocking farms with shrimp that are free of diseases, the implementation of effective disease management, better management of land and water usage, and the treatment of effluents can reduce loss due to diseases.
One hudred and twenty isolates of Bacillus sp. were collected from the intestines of striped catfish ( Pangasianodon hypophthalmus [Sauvage, 1878]) reared in farms in three provinces in the southern part of Vietnam: An Giang, Can Tho and Dong Thap. Isolates were identified by multiplex and single PCR using specific primers designed on gene 16S rRNA for six species of Bacillus ( B.Subtilis,B. amyloliguefaciens, B. cereus, B. megaterium, B. licheniformis and B. pumilus ). The in vitro analysis included inhibition activity against the pathogenic bacterium Edwardsiella ictaluri, protesase activity, stomach acidity and bile tolerance test, and antibiotic susceptibility. Results indicated that the highest number of isolate was B. megaterium and none was identified as B. licheniformis. The strain B. amyloliquefaciens 54A showed high protease activity and B. pumilus 47B showed high ingibition activity against E. ictaluri. These two probiotic candidates were also resistant to stomach acid pH and low bile salt conditions after 3 h and 24 h of exposure. Bacillus sp. candidates displayed varying sensitivities to the tested antibiotics with the exception of spectinomycin.
Evaluation of the possibility of using filter feeder freshwater clam, Pilsbryoconcha exilis compressa, for the improvement of water quality in tilapia closed culture system was evaluated in a 2 month outdoor tank experiment. Tilapia was cultured in a closed system with and without freshwater clam for two months. Average values of turbidity, chlorophyll a, total particulate matter, particulate organic matter, particulate nitrogen and particulate phosphorus in tilapia-freshwater clam treatment were significantly lower (P≤0.05) than those in tilapia only treatment. However, there was no significant difference (P≥0.05) between the average values of total ammonia nitrogen from the two treatments. Average values of turbidity, chlorophyll a, total particulate matter, particulate organic matter, particulate nitrogen, particulate phosphorus and total ammonia nitrogen were 6.0 ±11.6 NTU, 24.3±15.8 μg/L, 7.9±6.1 mg/L, 6.4±5.1 mg/L, 1.419±1.342 mg/L, 0.087± 0.058 mg/L, and 0.473±0.267 mg/L, respectively, in tilapia-freshwater clam treatment. In comparison, tilapia only treatment yielded average values of 22.0±11.6 NTU, 324.1± 222.2 μg/L, 42.5±26.2 mg/L, 34.1±21.1 mg/L, 5.291±5.634 mg/L, 0.305±0.189 mg/L and 0.599±0.752 mg/L, respectively. According to the results of this experiment, P. exilis compressa is effective in removing particulate matter, particulate nitrogen, phytoplankton and particulate phosphorus from water in tilapia culture tanks resulting in the decrease of 72.7% of turbidity, 81.4% of total particulate matter, 81.2% of particulate organic matter, 92.5% of chlorophyll a, 73.2% of particulate nitrogen and 71.5% of particulate phosphorus. There was no significant difference (P≥0.05) between production rate, survival rate and growth rate of tilapia in both treatments.
The gut contents of the Indochinese molluscivorous catfish, Helicophagus leptorhynchus were investigated. The fish were collected from the Mun River, the largest Mekong tributary in Thailand, between February 2008 and February 2009. Two sampling sites with different geographical characteristics, i.e. Tha Ngoi and Khong Chiam, were selected. The first site has a muddy and sandy bottom and the other site has rapids with deep pools. Food items were dominated by mollusks with some other food types occasionally found. Twenty species of mollusks, both gastropods and bivalves, were observed, namely Corbicula moreletiana, Pachydrobia zilchi reducta, Melanoides tuberculata, Lacunopsis munensis and Limnoperna siamensis. The finding is contrary to previous reports on the feeding habits of H. leptorhynchus which said that this fish species feeds exclusively on bivalves. This study showed that food items were manipulated by space and time as well as life stage of the fish. Results also showed that the larger the fish grows, the bigger the mollusks that are being chosen as food.
A 60-day feeding trial was conducted to evaluate the effects of formic acid (Amasil ® NA), β-carotene (Lucarotin ® 10% Feed) and vitamin E (Lutavit ® E 50 S) on growth, survival, prevention of Vibrio infection and immune parameters of Pacific white shrimp. In Experiment 1, postlarvae-12 were randomly distributed into six groups and then fed four times daily with the following diets as treatments: 0.3% formic acid, 50 ppm β-carotene, 50 ppm β-carotene + 0.3% formic acid, 400 ppm vitamin E and no feed additives (positive and negative control groups). After 30 days of the feeding trials, the body weight of shrimp fed with 50 ppm β-carotene was significantly higher than those of the control groups, whereas the survival rate was not different among all treatment groups. In Experiment 2, Vibrio parahaemolyticus was added to all tanks except the positive control to obtain a final concentration of 10 4 colony-forming units/ml. Each treatment group received the aforementioned diets for another 30 days. At the end of the trial, shrimp fed with 50 ppm β-carotene and 400 ppm vitamin E had significantly higher body weight compared to the negative control. Apart from the positive control, the highest survival rate was observed in shrimp fed a diet containing 0.3% formic acid, while immune parameters of shrimp fed a diet containing β-carotene were significantly improved. In summary, dietary formic acid and β-carotene exhibited positive effects on shrimp health.
Concentrations of heavy metals (cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), manganese (Mn) and zinc (Zn)) were determined in the liver, kidney, and muscle of Helicophagus leptorhynchus found in the Mun River, the longest Mekong tributary in Thailand. Sampling was conducted in three sites, covering the area from up- to downstreams. The concentration of Zn in the fish tissues was significantly higher than those of other heavy metals. Variation in concentrations of heavy metals was observed, and they varied according to space and time. The patterns of metal allocation in the studied organs were (a) liver: Zn > Cu > Cr > Cd > Mn > Pb, (b) kidney: Zn > Cr > Cd > Cu > Mn > Pb and (c) muscle: Zn > Cr > Mn> Cu > Cd >Pb.
The freshwater snail, Bithynia siamensis giomphalos, is the first intermediate host of liver fluke (Opisthorchis viverrini) in northeast Thailand. Wild broodstock of the snails from three dams, namely Nong Ham Dam (NH), Lampao Dam (LA), and Ubonrat Dam (UB) were collected and identified by sex. The male and female snails (2:3 sex ratio) were mated in a glass box (10x5x5.5 em) in three replicates. The average number of spawned eggs per day was highly significant in NH population (6.48-13.90 eggs) (P 0.05). The embryonic development composed of 5 stages, namely cleavage, morula, trochophora, veliger, and hippo stages. The breeding performance and embryonic development of snails may be essential for the control of 0. viverrini prevalence.
The partial cDNA sequences of the vitellogenin (VTG) gene were cloned from the liver tissues of Notopterus notopterus and Anematichthys armatus. The expression levels of VTG could not be directly used for investigation of the spawning season of the two fish species, but we can indirectly rely on their expressions as the information indicates relation with spawning season. The gonadosomatic index (GSI) and hepatosomatic index (HSI) were also examined for analysis of the seasonal changes in the two fish species. Fish samples were collected from June 2012 to May 2013. Significant variations of VTG expression levels (f'<0.05) were observed during the spawning season, from January (0.42 + 0.07%) to August (0.97 + 0.15%), and April (0.20 + 0.09%) to September (1.04 + 0.14%) for N. notopterus and A. armatus, respectively. The relationships between VTG genes expression, GSI and HSI values were determined using correlation analysis. The VTG expression levels have a significant (P<0 .01) direct correlation with the mean GSI values. The highest mean GSI values were also observed during the spawning season: August and September for N. notopterus and A. armatus, respectively. The mean HSI value has an inverse trend to the VTG expression and the mean GSI value. Thus, the VTG expression profile and the GSI values reflect the seasonal spawning on an annual basis of two fish species in Kwan Phayao.
The two-part study was conducted to ascertain the effect of climate variation on growth of key aquaculture species, i.e. mud crab raised as soft-shell crab, and phytoplankton, a key food source for shellfish. Data were collected from the districts of Khlung, Laemsing and Thamai, Chanthaburi Province, Thailand, using structured questionnaire, to determine the effect of climate variation on coastal fisheries. The first part of the study showed that sea temperature could significantly alter the growth rates of both mud crab and phytoplankton (p<0.05). The optimal temperature for mud crab growth was between 30 and 33°C, whereas growth rate of phytoplankton was highest with a shortest doubling time at 30°C. However, if the temperature exceeded 32°C, plankton population decreased with the rate declining with cascading effects on shellfish growth. The second part of the study revealed that fishers and aquaculture farmers perceived that climate variation affected their livelihoods including fisheries and aquaculture production. These climate variations included raining during non-rainy season, increased rain fall, severe waves, and changes in monsoon timing. In order to deal with climate variation events, fishing communities should listen to news regarding the weather before making decisions and should exchange information within their communities. Additionally, the government should develop an effective method for forecasting weather, rainfall, and freshwater runoff, and communication channels should be improved.
The microzooplankton community was studied in February, June and November 2008 in Prasae Estuary, Rayong Province, located along the eastern coast of the Inner Gulf of Thailand. Microzooplankton was collected by horizontal hauling with a 125 !Immesh size plankton net. Twelve stations were used for sampling in three study areas of Prasae Estuary, namely the inner riverine, estuarine and marine sections. Several hydrographical parameters were measured. Thirty-two groups of microzooplankton were recorded. The holoplankton was more abundant than meroplankton. The most diverse sample was found in the marine section (32 groups), followed by the estuarine mouth (23 groups), and the inner riverine area (16 groups). The pooled data of all samples showed the highest average abundance in the estuarine area, followed by the inner riverine area, and the marine section (2,679 ± 1,563, 1,755 ± 1,043 and 1,097 ± 877 ind. I11-3, respectively). The dominant group was copepods, comprising between 70-87% of the total microzooplankton abundance. The microzooplankton community showed temporal variation in abundance in the annual cycle. The inner riverine and marine sections had the highest abundance in February while the estuarine mouth showed the highest abundance in June. In this regard, the monsoon season might be the main factor influencing the microzooplankton community in this study area.
Investigation on the efficiency of two water recirculation systems for hybrid catfish were conducted in culture systems using a plate separator + trickling filter and a swirl separator + trickling filter, for water treatment. Hybrid catfish with an average size of 50 g were stocked in 1000 liter-culture tanks at the rate of 400 ind/m 3 . Turnover rate of water in fish culture tank was 2.0 hrs. Culture water flowed through a suspended solid treatment unit at the rate of 8.3 L/min. Culture period was 80 days. Results were compared with a water exchange system in which water in culture tanks were exchanged at 50% daily. Based on the results of this study, both water recirculation systems using either plate separator + trickling filter or swirl separator + trickling filter for water treatment were very effective for controlling total suspended solids (TSS), ammonia and nitrite in culture water. Average values of TSS, ammonia and nitrite in culture water in both water recirculation systems were significantly lower (P<0.05) than average values of these parameters in the water exchange system. Average values of TSS, ammonia and nitrite in culture water were 62.21-111.65 mg/L, 2.01-3.88 mg-N/L, and 1.10-4.50 mg-N/L in water recirculation systems with plate separator + trickling filter, 63.90-90.56 mg/L, 1.55-2.86 mg-N/L, and 1.02-3.50 mg-N/L in water recirculation systems with swirl separator + trickling filter, and 200.73-478.73 mg/L, 5.94-19.46 mg-N/L, and 3.23-20.56 mg-N/L in water exchange culturing system, respectively. Production, final weights, and survival rates of fish in both water recirculation systems were significantly higher (P<0.05) while FCR was significantly lower (P<0.05) than those of fish in the water exchange system.
The effect of Anta ® Qx FlavoSyn, polyphenol-rich feed additive from grapes, on the health and tolerance to Vibrio infection in Pacific white shrimp was studied under laboratory conditions. In experiment 1, postlarvae 12 were stocked in an 18 x 500-L fiberglass tank at a density of 50 PL!tank. Water temperature and salinity were maintained at 29 ± 1°C and 20-25 ppt, respectively. Shrimp were distributed into three groups (with six replicates/treatment), then fed four times/day with normal pelleted feed (control group), or feed mixed with 400 and 800 ppm Anta ® Qx FlavoSyn. After 60 days of feeding trials, the body weights of shrimp fed with 400 and 800 ppm Anta ® Qx FlavoSyn were 3.42 ± 0.22 and 3.48 ± 0.18 g, respectively, both significantly higher than those ofthe control group (2.64 ± 0.43 g). However, there were no differences in the survival rates and FCR from the three experimental groups. In experiment 2, 30 shrimp from experiment 1 were randomly stocked in new 18 x 500-L fiberglass tanks with six replicate tanks per treatment. At the beginning of the trial and 14 days later, Vibrio parahaemolyticus was added into each tank to obtain a final concentration of 104 CFU/ml. Each treatment group was fed the aforementioned diets four times daily for 30 days. All water quality parameters were maintained as in experiment 1. At the end of this experiment, 800 ppm Anta ® Ox FlavoSyn fed shrimp had a survival rate of 78.33 ± 1.92%, significantly higher than that of the control group (64.17 ± 1.67%). The hepatopancreas of the former showed less necrotic cells as well. Nevertheless, weight gain, total intestinal Vibrio spp., and total bacterial count were not significantly different among all experimental groups. The present study indicated that Anta ® Qx FlavoSyn had a positive effect on their growth and survival.
This study aimed to analyze costs and returns including marketing channel and share of salted fish products produced in Pakphayun district, Phatthalung province, Thailand. The study was conducted by interviewing 14 salted fish producers in the study area using questionnaires, and data analyzed by rapid market appraisal (RMA). Results showed that the most common fish species used to produce salted fish products were Gunther's walking catfish (Clarias macrocephalus), croaker (Otolithes ruber), spotted catfish (Arius maculatus) and soldier catfish (Osteogeneiosus militaris). Salted fish produced from Gunther's walking catfish generated the highest total cost per kg at 122.36±6.58 THB followed by croaker, spotted catfish and soldier catfish, with total costs of 95.75±6.28, 86.61±6.80 and 81.70±9.71 THB, respectively. The total revenues per kg of each type of product were 140, 110, 100 and 100 THB, respectively. In terms of profit, salted fish produced from soldier catfish generated the highest profit per kg at 18.30±9.71 THB, followed by Gunther's walking catfish, croaker and spotted catfish, at 17.64±6.58, 14.25±6.28 and 13.39±6.80 THB, respectively. Producers distributed 50% of salted fish products to consumers directly, 40% to retailers, and 10% to wholesalers.
Seaweed is a promising resource for bioethanol production because of its high carbohydrate content. This study utilized the red seaweed, Gracilaria tenuistipitata, as feed stock for the production of ethanol due to its high biomass in cultivation. This work aimed to improve ethanol production from algal species using different concentrations of hydrochloric acid during pretreatment. Samples of Gracilaria species were gathered from earthen ponds. The algal samples were pretreated with 0.5, 1.0, and 2 M HCl at 95°C for 15h. The yeast strain Saccharomyces cerevisiae TISTR No.5339 was used as the ethanol producer. Yield of ethanol was analyzed by gas chromatography. The highest yeast cell mass of2.42x10 8 cells m.L -1 was obtained from fermentation of 1M HCl hydrolysate. Under the fermentation condition, pretreatment of the alga with 1M HCl gave a higher yield of ethanol (0.32 g ethanol g -1 sugarsl than those with 0.5M HCl (0.29 g ethanol g -1 sugars) and 2M HCl (0.22 g ethanol g -1 sugars). Our study suggested that the acid pretreatment improved ethanol yield during algal fermentation.
Comparative assessment of plasma cortisol and expression of Heat Shock Protein 70 gene (HSP70) from gill tissue as indicators of temperature stress in Nile tilapia (Oreochromis niloticus) was investigated. In this study, water temperature at 22, 27 and 32°C was the stressor. Results revealed that the concentration of plasma cortisol responded to temperature stressors at irregular patterns as compared to its response to ambient water temperature. In contrast, fish reared at 22 and 32°C showed significantly higher levels ofHSP70 expression than those exposed at control temperature (27°C), at 3 and 6 hours after stress induction (P<0.05). However, during 12-168 hours, a significant difference in HSP70 expression was observed only in fish exposed at 32°C water. Studies on correlation between temperature and the severity of Streptococcosis infection in Nile tilapia revealed that fish challenged with Streptococcus agalactiae through immersion at 32°C for 21 days had significantly higher mortality than fish challenged at lower temperatures (P<0.05). Accumulative mortality rate of31.67% was observed in 32°C fish while only 8.33±1.53% and 8.33±0.58% were observed in fish reared in 22 and 27°C water, respectively. This study indicated that the expression of HSP70 gene may be an indicator of temperature stress in Nile tilapia. Since the HSP70 is an important molecule of fish that can respond to various stressors in order to regain the homeostasis of the body, results from this study provide valuable information for further research to investigate whether HSP70 expression can be used specifically as a reliable indicator for other stressors.
This study was carried out to produce crude salmon oil from salmon bellies and purified oil by three purification stages: degumming with three different agents (hot water, 85% phosphoric acid, and 0.3% citric acid), neutralization with alkali, and bleaching with activated carbon. The crude and purified oils were analyzed for yield, peroxide value, p-anisidine value, free fatty acid, heavy metal and fatty acid composition. The results showed that yield of refined salmon oil was 33.7% of raw material used. Free fatty acid content, and peroxide and p-anisidine values were within acceptable ranges which indicated that the refined oil produced was of an acceptable quality. The degummed oil using citric acid and phosphoric acid had reduced iron and copper contents when compared to those formed in oil degummed with hot water, and the values were within the standard for edible fish oil. Besides fatty acid composition, refined oil showed a higher percentage of monounsaturated fatty acids and polyunsaturated fatty acids. The ratio of omega-3 to omega-6 fatty acids was about 1.58-2.17.
Effect of dietary astaxanthin and background color on pigmentation and growth of red cherry shrimp ( Neocaridin a heteropoda ) was investigated. A 2x3 factorial in CRD with two types of diets (with astaxanthin supplementation of 200 mg astaxanthin.kg-1 and without supplementation) and three types of background colors (white, red and black) was conducted. After the 8 weeks feeding trial, the results indicated that dietary astaxanthin and background color had no interaction effect on pigmentation and growth performance (P>0.05). Astaxanthin-fed groups had significantly greater pigmentation than that of shrimp fed without astaxanthin (P 0.05) and among background colors. All results indicated that red cherry shrimp fed with astaxanthin and reared in black or red background colors can increase pigmentation, weight gain and SGR.
The blue-spotted mudskipper, Boleophthalmus boddarti, is an important commercial fish species found in coastlines and estuaries in the Mekong Delta. This amphibious, mudflat inhabitant fish can directly respire air at mud surface. Despite its high economic value, information on biology and ecology, especially burrow structure is scarce. This study was carried out in order to understand burrow morphology and utilization purpose. The study was conducted for six months, from February to July 2013 in the Mekong Delta at Cu Lao Dung, Soc Trang province, Vietnam. The structure of the blue-spotted mudskipper burrow was studied by using resin castings on burrows in situ technique. Burrow structure of this species comprised one to two openings with footmarks made by its pectoral fins with one to two bulbous chambers. In general, burrow shapes were I and U types with one to two slightly slanting tunnels attaching the chambers together with some short cul-de-sac side branches. Moreover, the burrow had no mound at the opening. Results revealed that burrow structures have a strong relationship with fish size. The blue-spotted mudskipper uses a burrow as a place for foraging prey, living, refuge from predators, and spawning.
