This research was conducted to determine the effect of feeds (algae, formulated feed, and combination of Spirulina flakes and formulated feed) and salinity (25‰, 30‰, 35‰) on growth rate and survival rate of dog conch at the veliger larval stage. The experiments were carried out from February to May 2017 in Nha Trang, Khanh Hoa province. The results showed that the growth rate of larvae was highest (46.3 ± 4.41 μm/day) in the treatment fed with combination of Spirulina flakes and formulated feed and significant differences were recorded among treatments. The survival rate of larvae in the treatment fed with algae (76.2 ± 2.3%) was significantly higher than those in the other treatments. The growth rate and survival rate of larvae in the treatment of 30‰ was highest (39.1 ± 4.74 μm/day and 70.4 ± 2.52%, respectively) and significantly different from the treatment of 25‰.

The aims of this study are to determine technical aspects and financial effeciency of mud crab hatcheries in the Mekong Delta. The study was conducted from August to December 2017. Thirty-four mud crab hatcheries were directly interviewed in 3 provinces in the Mekong Delta: Kien Giang, Bac Lieu and Ca Mau. The results showed that the average hatchery area was 516±1,096 m2, total volume of larval rearing tanks was 234±414m3 (average 4±2 m3/tank) and production were averaged at 6 cycles per year. Of 34 mud crab hatcheries interviewed, 32.4% hatcheries cultured broodstock for maturation and spawning, and 67.6% hatcheries bought berried broodstock from other hatcheries. The average stocking density of larvae was 395±141 individuals/L and after 9 days of nursing, larvae were transferred to another tanks for density reduction at average density of 82±31 individuals/L. After 25 days of nursing, average survival rate was 4.6% (ranging from 2.3 to 7.7%), average yield was 5,492±2,500 crablets/m3 and the production was 1.29±2.22 millions crab/cycle/hatchery. There was 91.2% intervied hatcheries gained profit whereas the rest lost their income. For the hatcheries gaining profit, total production cost was averaged of 23.4 milions VND/spawning (228.7±92.9 milions VND/hatchery/cycle) and net profit of 9.5 milions VND/spawning (89.0±167.2 milions VND/hatchery/cycle); the profit margin was 0.41±0.27. For the unsuccessful hatcheries, they lost their investment from 1.9 – 4.2 milions VND/spawning (7.4 – 16.9 milions VND/cycle/ hatchery).

The aim of the study is to identify the reasons and causative agents related to clam mortality at Nam Dinh province in 2016-2017, which mainly focuses on the microorganisms volatility and the changes of some environmental factors. Samples including water, sediment and clams in different areas of low, mid and high tide were collected and analyzed for the presence and density of Vibrio bacteria and common water parameters such as pH, salinity, temperature, ammonia, nitrite and hydrogen sulfide in predetermined periods.  Then, t-test and one-way anova analysis were used to access the impacts of those parameters on the clam health.  The results showed that low mortalities (1-10%) of clams had occurred at high tidal growing area in April 2016 and May 2017. Mortalities were observed only on clams in big size at high density areas of 500-600 individuals/m2. Clams did not show specific clinical signs, and histological results showed minor injuries on their shells and gills. Correlation analysis revealed some biotic components related to clam health status; they were number of Vibrio bacteria in water (2068,2 cfu/ml), in mud (9713,5 cfu/g), in clam (2241,3 cfu/g)) and amount of V. parahaemolyticus (96,8 cfu/g) in clam. In addition, some abiotic factors were also correlated with clam mortality. Clam deaths occurred at low tidal areas due to long exposure to sunlight (5-6 hours), high temperature (23- 260C in 2016 and 32-380C in 2017), and high salinity (19-21‰ in 2016 và 23-27‰ in 2017). However, temperature and salinity parameters measured at the two events were not as high as those in previous mass mortality cases in Nam Dinh province. This might be a reason for no serious clam death occurrence in 2016 and 2017.

The effect of the extracting solvents (distilled water, 70% ethanol and 70% acetone) on the phenolic and flavonoid contents in pandan leaf extracts (Pandanus amaryllifolius) was investigated. The results indicated that pandan leaf extracted in ethanol at the concentration of 70% showed the highest phenolic (163±4.50 mgGAE/g) and flavonoid contents (23.6±0.49 %). This pandan extract was added into tempura black tiger shrimp (Penaeus monodon) product and the quality changes of shrimp was investigated by analyzing Peroxide (PV), Thiobarbituric acid reactive substances (TBARS) values, total volatile base nitrogen (TVB-N), texture, sensory and total viable counts during 18 days of refrigerated storage (4±2ºC). After 9 days of storage, the shrimp treated with 2% of extract showed the lower lipid oxidation with a PV of 6.92 mgMDA/kg and a TBARS value of 6.20 meq/kg and, while PV and TBARS values of the control samples were 8.75 meq/kg and 7.51 mgMDA/kg, respectively. Furthermore, the treated group had better sensory properties, better smell compared with the control sample at the same storage time.

Ảnh hưởng của nhiệt độ cao lên tôm sú (Penaeus monodon) giai đoạn tôm bột (postlarvae) lên giống (juvenile) được tiến hành với 5 nghiệm thức nhiệt độ (27-28, 30-31, 33-34, 36-37 và 28,5-29,5oC (đối chứng). Thí nghiệm bắt đầu từ tôm 0,02 g/con, trong 45 ngày, bể ương 250 lít, mật độ 100 con/bể và mỗi nghiệm thức lập lại 3 lần. Tăng trưởng tôm được xác định mỗi 15 ngày; cuối thí nghiệm thu mẫu máu phân tích glucose, mẫu ruột và dạ dày phân tích enzyme tiêu hóa (trypsin, chymotrypsin, amylase). Tỉ lệ sống giảm theo nhiệt độ tăng, 0% ở nhiệt độ 36-37oC, 65% ở nhiệt độ 27-28oC (cao nhất) và 63,7% ở nhiệt độ đối chứng. Tăng trưởng khối lượng (0.015 g/ngày) cao nhất ở nhiệt độ 30-31oC. Hàm lượng glucose cao nhất ở nghiệm thức 33-34oC (12,11 mg/100 mL) khác có ý nghĩa thống kê (p

The study aims to provide initial data on species composition, taxon structure, fish species of reservation importance in Sao La conservation area, Thua Thien Hue province. Samples were collected directly in the field, shaped with 40% formol solution. Pictures were taken immediately when fresh; measure the outer form according to Pravdin (1961), Nguyen Van Hao (2001). Identify fish species by comparison based on the identification of Mai Dinh Yen (1978), Rainboth (1996), Kottelat (2001a and 2001b), Nguyen Van Hao and colleagues (2001, 2005a and 2005b). Class, order, family, genus, and species according to Eschmeyer, 2017 and other authors. The research results have identified 73 species belonging to 47 genera, 20 families, 08 subclasses of 08 classes. Cypriniformes predominate in families, breeds and species with 9 families (45% of total families), 10 genera (21.27% of total genera), 49 species (67.12% species). Two species of conservation value have also been identified in the Red Data Book of Vietnam (2007), 07 species named in Decision No. 82/2008/QD-BNNPTNT and Circular No. 01/2011/TT-BNNPTNT of the Ministry of Agriculture and Rural Development; 59 species are listed in the IUCN Red List (2017) and 01 species is listed in Appendix II of CITES (2017), and four species are endemic in the central area of Vietnam.

This study was carried out to determine the antimicrobial activity of seven herbal extracts (Ricinus communis L., Hedyotis corymbosa L., Vernonia amygdalina del., Moringa oleifera, Callisia fragrans, Acanthus ilicifolius L. and Wedelia calendulacea (L) Less) which were collected in the Mekong Delta. Antimicrobial activity, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) of the seven herbal extracts were screened for two common shrimp pathogens (Vibrio harveyi and Vibrio parahaemolyticus). The results showed that (i) seven herbal extracts have different antimicrobial activity; the extract of R. communis showed the highest diameter of the inhibition zone from 17 -18 mm, followed by the extracts of V. amygdalina del., M. oleifera, A. ilicifolius L. and W. calendulacea (L) Less. with the inhibition zone range of 10 - 11 mm. Similarly, the smallest inhibition zone was recorded for the extracts of H. corymbosa L. and C. fragrans) at 7 and 8 mm, respectively; (ii)  The results suggested that were also found to be effective at the extract of R. communis L for against V. harveyi, V. parahaemolyticus, with MIC and MBC values were 1.25 mg ml-1 and 2.5 mg ml-1; 2.5 mg ml-1 và 5.0 mg ml-1, respectively.

This study is aimed to estimate the reproductive performance of domesticated female black tiger shrimp in the fourth generation G4 indoor- rearing which is produced from the project “Study of bio-technological application to select black tiger shrimp (Penaeus monodon) broodstock with fast growth characteristic”. The maturation ratio of the shrimp G4 was 100%. At the 1st spawning, the spawner was 73,3±6,6g in average body weight, 50% in spawning ratio, 283.556±75.801eggs each spawner in the practical reproduction, 84,9% ±7,5% in fertilized ratio and 96,3% ±3,4% in hatched ratio; At the 2nd spawning the data were:  78±2,5 g, 75,9%, 265.600±97.240 eggs per spawner, 91,8%±3,4% and 92,1%±4,4% respectively; and at the 3rd spawning the data were 75±7,5 g, 18,2%, 204.444±34.667 eggs per spawner, 72,4%±16,2% and 60,5%±45,4%. The results indicated that the practical reproduction, fertilized ratio and hatched ratio of the shrimp at the 3rd spawning significantly declined (p

The study was conducted to assess the technical and financial status of hard clam/ white clam (Meretrix lyrata) farming in the context that the habitat in Tien Giang has faced climate change and increasing pollution. The research results determined technical status as follows: average farming area/household (6.4 ± 1.09 ha), stocking size (2,604 ± 527.5 inds./kg), the amount of stocking  (2.3 ± 0.29 tons/ha), stocking density (387.9 ± 71.7 inds./m2), farming  period (17.5 ± 1.23 months), harvesting size (56.6 ± 1.04 units/kg), and survival rate (34.1 ± 1.12%). The average productivity (13 ± 1.28 tons/ha) was correlated to ground condition, area, density and farming period. Economic status includes selling price (15.6 ± 0.77 thousand VND/kg), production cost (103.6 ± 12.42 million VND/ha/crop), and turnover (198.4 ± 19.1 million VND/ha/crop). The average profit (94.8 ± 15.9 million VND/ha/crop) was closely correlated to the farming area, yield, stocking density, and farming period. In addition, several difficulties and challenges that hard clam farmers in Go Cong Dong are facing including complete dependence on nature, scarcity of natural stocks, disease, and lack of capital for production. However, 90% farmers insist on continuing local hard clam production.

The shrimp production in Vietnam is threaten by the outbreak of many diseases, especially Acute Hepatopancreatic Necrosis Disease caused by Vibrio parahaemolyticus leading up to 100% mortality rate in a short period in shrimp farms. Applying fungal mycelium can be a new potential approach to counteract the disease with advantages of low cost and environmental friendly. In this study, mycelia system of Schizophyllum commune, Pleurotus ostreatus and Pycnoporus sanguineus were used in the small-scale aquaculture system to examine the potential of applying fungal mycelium in controlling the pathogen Vibrio parahaemolyticus. Penaeus vannamei were challenged by adding Vibrio parahaemolyticus suspension at the concentration of 105 CFU/mL. The mycelia were applied into each Penaeus vannamei PL30-35 culture tanks with about 5 grams of substrate covered by fungal mycelium. The results shown that the Pycnoporus sanguineus mycelium can remove 99% of V. parahaemolyticus despite having low survival rate of the white leg shrimp, approximately 65% survived after challenging. Modifications needed to be applied to this design in order to maximize the potential and improve its performance in future researches.

The aim of this study was to investigate the antioxidant property of Spirulina (Anthrospira platensis) powder extracts which could be applied in aquatic product preservation. The extracts of Spirulina powder were prepared by two solvents such as hot water at 100○C in 3 hours and 90% ethanol extraction in 12 hours. This study included two experiments: (i) to investigate the antioxidant activity of Spirulina extracts through evaluating the capacity of elimination free radicals DPPH and the total phenolic compounds presented in the extract, (ii) to assess the antioxidative efficiency of Spirulina extract supplemented in soybean oil, marine fish oil and catfish oil at 60○C. Results showed that the extract obtained from ethanol had higher DPPH free radical scavenging at 67.1% (IC50 = 0,66 mg/mL) compared to hot water extracted sample, which possessed higher total phenolic compounds at 7,47 mgGAE/g of dry matter. These indicated the potential application of Spirulina extract from ethanol in preservation of soybean oil and marine fish oil.

Probiotic is extensively used in aquaculture for enhancement of water quality, disease control, and immune system of aquatic organisms. This study was carried out to determine the effectiveness of the probiotic (Bacillus subtilis) as a water additive in mud crab (Scylla paramamosain) larviculture. Bacillus subtilis was weekly added at 106 CFU/mL and control treatment without probiotic. The result showed that probiotic could help to improve the water quality as TAN, nitrite, and Vibrio density were significantly lower compared to the control treatment (p

The objective of this study was to determine the composition of the natural food uptaken by black tiger shrimp (Penaeus monodon) in improved extensive ponds. The study was conducted with 14 sampling periods in three shrimp ponds in An Bien district, Kien Giang province, where shrimp were stocked at density of 1-3 inds/m2. The average pond area was ​​1.5-1.7 ha with a depth of 1.2 m. Water was exchanged once a month. A certain number of shrimps was suplemented in the ponds once a month, and no feed provided during the culture period. Thirty shrimps were collected each time for analysis of feed composition in their digestive tract. Water parameters including temperature, pH, salinity, TSS, TN and TP were also recorded. The results showed that the water parameters are suitable for the development of natural food and growth of shrimp in ponds. Variation of natural food depended on nutrient content and salinity in the water environment. Besides detritus with high proportion, the study identified a total of 10 natural food groups in the digestive tract (DT) of shrimp. The composition and quantity of natural food of shrimp were recorded from 8-23 genera and 6-6,289 individuals/DT, respectively. Shrimp with an average length of 1.5±0.4cm to 3.6±0.6cm utilized mainly Bacillariophyta, Rotifera, Copepoda, Polychaeta and detritus. Adult shrimps with a size of 12.3±0.7cm consumed a lot of detritus and Polychaeta. In general, as shrimps grow up from 4.8±0.5 cm to 5.3±0.8 cm, their feeding spectrum changes from planktonic to benthic organisms.

Investigating species composition of green seaweed belonging to Cladophoraceae family in brackish water bodies of Bac Lieu and Ca Mau provinces was conducted monthly from May 2015 to April 2016. Sampling was done at different water body types including the improved extensive shrimp ponds, abandoned ponds, and discharged canals. Results showed that 15 species of green seaweed found belong to three genera, including Cladophora (seven species) Rhizoclonium (five species) and Chaetomorpha (three species). The occurrence frequency of green seaweed species in the improved extensive shrimp ponds was higher than that in the abandoned ponds and other water bodies, and the number of green seaweed species was observed from 5-11 species in each month. Green seaweeds developed year-round, and their species composition was controlled by seasonal variation especially salinity. Their species’ number was highest in May (11 species) and lowest in October (five species). The species composition of green seaweed was affected by dominance of other seaweed species and aquatic plants co-existing in the water bodies.

Feeding trial was conducted to evaluate the effects of hot water-extract from the Sargassum microcystum supplementation in diet of black tiger shrimp (Penaeus monodon). Shrimps were fed the diets supplemented with different levels of S. microcystum hot-water extract (0%, 0.5%, 1%, 2% of hot-water extract)  for 30 days. The challenge experiment was conducted in 60 L plastic container with 30 shrimps for each treatment. Immune parameters including total haemocyte counts (THC), total granular cells (including semi-granular cells) (LGC), total hyaline cells (HC), phenoloxidase activity (PO) and resistance to Vibrio harveyi were evaluated. Results showed that (i) THC, LGC, HC, PO activities were significantly increased in the shrimps fed with 1% hot-water extract supplemented diet; (ii) the highest survival rate (80%) was significantly recorded in the group that was fed with 1% of hot-water-extract. The results suggested that feeding 1% hot-water extract from S. microcystum could enhance immune responses and resistance against V. harveyi in black tiger shrimp P. monodon.

Different feeding rates were applied to determine the growth rate and biomass increase of juvenile black apple snail, Pila polita, in rearing stage. The experiment included 4 feeding treatments as follows: 1). Feeding 3% of snail biomass (SB) in 5 weeks of experiment (F3-3); 2). Feeding 3% SB in week 1 and increasing to 5% from week 2 onward (F3-5); 3). Feeding similar to treatment 2 in first two weeks and increasing to 7% from week 3 onward (F3-7) and 4). Feeding similar to treatment 3 in first 3 weeks and increasing to 10% from week 4 onward (F3-10). Juvenile snails (initial weight at 0.10 - 0.13 g and shell height from 7.05 - 8.03 mm) were reared in PVC tanks (40 × 80 cm) at the stocking density of 300 ind./m2 and fed with commercial pellet (18% protein). After 5 weeks, the survival rate was not significant difference among treatments (p>0.05). However, snail weight and height (1.66 g and 20.2 mm) in F3-10 was significantly higher than in others (p

Study on the current status of single trawler (vessel> 90CV) of offshore areas in the Ca Mau province was conducted from January to April 2018 in Tran Van Thoi and Phu Tan districts, Ca Mau province. Forty five offshore single trawler households were interviewed with main contents such as fishing gears, fishing boats, fishing grounds, fishing crops, exploited species, yields, trash fish ratio, financial performance, advantages and disadvantages. Results showed that the number of offshore trawlers in Ca Mau province was 295 fishing boats. Offshore trawlers with average capacity of 295 CV/vessel and average tonnage 18.6 tons/vessel. The offshore trawlers can capture whole year round, the months of high production were from November to February of the following year. The average of yield was 88.7 tons/vessel/year, which accounted for 24.3% of trash fish. The total average cost of a fishing trip was 50.45 million VND and net return was 35.39 million VND/fishing trip, benefit ratio was 0.72 times. For the sustainable development of offshore trawlers, supporting fishermen to access low interest rates to invest in production, the development and management of fisheries resources should be promoted, and training fishermen to use fishing equipment to increase their fishing efficiency.

Extended-spectrum beta-lactamases (ESBLs)-producing Escherichia coli causes serious diseases in human. The aim of this study was to characterize genotypic of 40 ESBL-producing E. coli isolates which were isolated from 18 wild fish samples (Pangasianodon bocourti, Pangasianodon conchophilus) and 54 farmed fish (Pangasianodon hypophthalmus and Oreochromis sp.) collected from An Giang, Vinh Long, and Dong Thap provinces. The results significantly indicated that: (i) ESBL-producing E. coli isolates collected from those provinces contain common beta-lactamase genes including blaTEM (6 isolates), blaCTX-M-1 (6 isolates), bla­CTX-M-9 (7 isolates) and some isolates contained both blaTEM+CTX-M-1 and blaTEM+CTX-M-9 genes; (ii) collected ESBL-producing E. coli isolates belong mainly to group A (17 isolates) and B1 (17 isolates). Specially, our study found the six remaining isolates belong to group B2 (three) and group D (three) which have virulence factor.

The study was conducted to deterimne the suitable supplementation level of lecithin in formulated feeds for larvae of mud crab, Scylla paramamosain consisting of two rearing phases. (1) From zoea 3 to megalopal stage, (2) From megalopal stage to crablet 1. The experiment was completely randomized with 5 replications of five feeding treatments. The test diets had isonitrogenous (53%), isolipid (12%), were supplemented with different lecithin levels of 0% (control diet), 1%, 2%, 3% and 4%. Crab larvae were co-fed Artemia and experimental feeds during larval rearing period. The results showed that when rearing from zoea 3 to megalop stage, which received the diet supplemented with 3% lecithin gave significantly higher larval stage index, survival, length and weight) of megalopa than those in the control diet. When rearing from megalopal stage, the carapace width, weight and survival of crablet1 inthe 3% lecithin group were highest and significantly different from other feeding treatments except the 2% and 4% lecithin treatments for survival. These results suggested that formulated feeds supplemented with 3% lecithin could be considered the suitable level for larval rearing of mud crab S. paramamosain.

Polychaeta are generally recognized as major group of segmented worms with no common morphological features. They spend most of their life burrowing underground in the U-shape burrow. They were firstly known as the bailt in the fisheries industry all over the world. Through deeper studies, this group has been known with many roles in environmental bioremediation and has been playing important roles in the biodegradable processes. Moreover, they are significant feed in aquaculture and are also applied as a substantial sector in the sustainable aquaculture system – the multi-trophic aquaculture system. This article is to summarize some biological features of polychaeta and their important roles in the aquaculture industry.

Morphometric parameters are especially important in morphometric analyses in fish. However, the measuring is extremely time-consuming and often difficult to be repeated. Image analysis approach has been applied widely in measuring mophometrics of different species. The study was aimed to test the feasibility of image analysis approach in conducting morphological characters of two morphological groups of fish (1) Cylintrical-bodied fish (Clarias macrocephalus and Clarias gracilentus) and (2) compressed-bodied fish (Cyclocheilichys apogon). The principle of this approach is to convert the measure unit in image pixel to a length unit in reality through a length factor SCALE determined by a unit scale on the image. The data from two methods were then compared using correlation analyses. The results revealed high correlation values (r>0.85) on most of morphometric parameters (17 out of 25 parameters), indicating the high accuracy of the image analysis approach on both fish morphological types. The image analysis approach is time effective, accurate, repeatable, and thus suitable in application for fish morphological research.

The aim of this study was to investigate the antimicrobial activity and to find suitable consentration of false daisy (Eclipta alba) and guava (Psidium guajava) extracts against Aeromonas schubertii causing the internal white-spot disease in snakehead (Channa striata). The diameter of clear rings in the antimicrobial testing both extracts false daisy and guava leaves at the same concentration 250mg/mL, 125mg/mL, 62,5 mg/mL were showed 20,83±0,76 mm, 16,00±0,00 mm, 14,00±1,00 mm and 23,17±0,29 mm, 16,67±0,58 mm, 15,00±1,00 mm, respectively. Both herbal extracts were suplemented into two groups of snakehead feed at the same concentrations of 1, 5, 10 g/kg and continuously feeding  for 45 days. The results of growth rate and FCR  of the herbal supplement groups were significantly higher (at p

The asiatic painted frogs were collected in Tien Giang and Ben Tre provinces in two seasons (sunny and rainy seasons). There were 400 individuals, including 202 small frogs (

The study was conducted from January to December 2016. Data was randomly collected by interviewing of 60 fishing households, who was internal living and 60 external living of irrigation works systems by using questionnaire. The objective of this research is to provide information on the income, living cost and consumption needs of the fishing households internal living and external living of the irrigation works systems in the study area. The results showed that fishing activities in sub-area of O Mon-Xa No Irrigation Project is one of the activities aimed at improving household incomes. Households external living of the irrigation works systems have an income of 93.4 million VND/year, which is higher than that of household internal living of 79.2 million VND/year. The average cost of households internal living is 3.43 million VND/month and the households external living is 3.86 million VND/month. The cost of buying fishery products ranges from 44.3 to 45% of total cost of living of the household. Consumer food of fishing households is quite diverse in types. In particular, fishery products are used by households more frequently than meat, poultry and eggs. Households external living of irrigation works systems was consumed more aquatic food than those internal living of irrigation works systems (4.2 kg/person/month compared to 3.5 kg/person/month). The average pork was consumed 1.1 kg/person/month and livestock products was consumed very little. consumption need for self-sufficient food groups of fishing households was predicted unchanging in the future.

The study was carried out to determine the viability of Kabatana sp. spores in artificial environment and the ability of drugs inhibiting Microsporidia infected in kidney and muscle cells of catfish. The results showed that kidney and muscle cells grew well in L-15 medium. The results of spore experimental challenges showed that, after 2 hours of challenge, kidney and muscle cells were invaded by spores, accounted for 11.68±2.60% of total kidney cells and 7.49±3.02% of total muscle fibers. After 12 hours, 100% of kidney cells and muscle cell fibers were invaded. Besides that, the results of drug experiments showed that Albendazole and Fumagillin, at concentration 5 µg/mL, had ability to inhibit Kabatana sp. infection in kidney and muscles cells, and can be applied to treat infection of spores caused by Kabatana sp. in catfish muscles.

The study aimed to investigate effect in light intensities on survival rate and growth performance of giant freshwater prawn under biofloc technology. The experiment included four treatments, (1) without shading, (2) one layer of shading net, (3) two layers of shading net, and (4) three layers of shading net. Nursing tank volume was 500 L. Shrimp fingerlings of 0.006 g/individual were stocked at 1,000 individual/m3, at salinity of 5‰. Rice flour was used at C/N ratio of 15 for biofloc production. After 30 days of nursing, treatment without surface covering yielded significantly (p

The research is aimed to define effective method to preserve single cell detritus (SCD) from green seaweed (Enteromorpha intestinalis) and assess the impact of using as feed for Artemia franciscana. Harvesting and preservation procedure of SCD included three stages: 1) Dried seaweed was ground into fine particles, and then sieved with mesh size 200 µm; 2) Seaweed powder was soaked in fresh water for 2 hours; then fermentation with yeast for 48 hours; 3) After that, the SCD product was sieved by mesh size 50 µm and centrifuged to obtain condense product and then separate into two parts. Part 1 was fresh (SCD-T) and was preserved at the temperature of 4°C, and part 2 was dried in oven for 48 hours at 60oC to obtain SCD powder (SCD-K). The results showed that the preservative time of SCD-T was shorter than 15 days at4°C. During preservative time, the density of SCD tended to decrease whereas SCD-K can be stored for more than 30 days. Artemia was fed by five different experimental diets while the control diet was shrimp feed No.0; the other diets included SCD-K, SCD-T with the replacement level of 100% and 50%, respectively. The diet with 100% shrimp food gave the best result of survival rate and reproduction of Artemia. However, replacement of SCD-K at 50% showed the positive results in survival rate (54.67 %) and fecundity of Artemia (34.1 offsprings/female). The findings showed that the diet with SCD-K proportion less than 50% should be studied more to apply for feeding Artemia.

This study is aimed to determine some common bacterial diseases on cage-cultured cobia (Rachycentron canadum) in Kien Giang province. A total of 34 bacteria isolates on 75 diseased samples were collected and isolated from 36 cobia cage-cultured  in 4 islands: Phu Quoc, Kien Hai (Nam Du), Kien Luong (Hon Nghe) and Tien Hai. All isolates were tested biochemical and biophysical characteristics by rapid testing systems, like using API 20E to identify Vibrio sp. and Photobacterium sp.; API 20 Strep combined with 16S rRNA gene partial sequencing to identify Streptococcus sp. Specifically, 14 isolates of Vibrio alginolyticus and 9 strains of Photobacterium damselae were obtained from hemorrhaged and ulcerative skin lesions. Whereas, 11 Streptococcus iniae isolates were isolated from cobia with pop-eye. Twenty-four isolates (8 trains of each isolated bacteria group) which were tested antimicrobial susceptibility showed high susceptibility to doxycycline and florfenicol. While, most V. alginolyticus isolates were resistant to ampicillin, streptomycin, and erythromycin. S. iniae was resistant to streptomycin, gentamicin; and 5/8 (62,5%) of this species was resistant to rifampicin. P. damselae showed the sensitivity to tetracycline, ampicillin, flumequine, cefotaxime, erythromycin, and rifampicin (50-90%).

The study was to investigate the changes of counts of coliforms and E. coli in Nile tilapia inoculated with E. coli during storage at 5 low temperature regimes (1, 4, 9, 15, and 19 ± 1°C). In order to have E. coli in all the samples, E. coli was injected into the fish at a known level (≤ 90 cfu/g) at the beginning of each storage. The initial counts of coliforms ranged from 5.6.102 cfu/g to 1.44.104 cfu/g. At the end of the fish shelf-life based on the total viable counts (≥ 106 cfu/g), coliforms in tilapia after 144 hours at 1 ± 1 oC, 120 hours at 4 ± 1°C, 120 hours at 9 ± 1°C, 24 hours at 15 ± 1°C, and 20 hours at 19 ± 1°C were 6.6.106, 4.17.106, 2.22.106, 1.15.106, and 7.64.106 cfu/g, respectively. The results showed that coliforms increased faster at higher storage temperatures, while the growth of E. coli was delayed at 1 ± 1°C and 4 ± 1°C.

This study is aims to evaluate suitable water salinity for Thai frog culture under saline water intrusion conditions in Tien Giang province and the Mekong Delta. The experiment is completely randomized with 4 replications of 5 treatments which are different level of salinity (0‰ – control, 2‰, 4‰, 6‰, and 8‰) for comparision of growth performance, survival rate and FCR.  After 60 days of experiment, Weight Gain (WG), Daily Weight Gain (DWG) of frogs were highest at treatment 0‰ (75 g and 1.25 g/day respectively), followed by treatment 2‰ (67.3 g and 1.12 g/day), and treatment 8‰ gave the lowest WG and DWG (49.5 g and 0.82 g/day). The survival rate was highest in the treatment of 4 ‰ (90%), followed by the treatment of 0‰ (88.8%) and lowest in the treatment of 6‰ (81.3%). However, there was no significant difference (p>0.05) among treatments. FCR was highest in treatment 8‰ (1.17) and lowest in the treatment of 0‰ (0.99), but the significant difference was not found (p>0.05). The results indicated that Thai frog can grow well in water salinity up to 6 ‰.

The objective of this study is to determine the diversity of zooplankton on Cai Lon river of U Minh Thuong district, Kien Giang province. The study was conducted in the period from February, 2017 to August, 2017. Zooplankton samples were collected at 6 times, of which 3 times were in the dry season, and 3 times were in the rainy season at six sites along the main river. The results showed that recorded 105 zooplankton species. The number of zooplankton species was highly variable according to the sampling season, from 71 in the rainy season to 95 in the dry season. Among them, Rotifera was the most abundant group with 47 species (44.8 %), followed by Copepoda with 23 species (21.9 %). In the study period, zooplankton density in Cai Lon river was at high levels, ranging from 14,167 to 62,000 individuals/m3.

Psidium guajava and Phyllanthus amarus are well-known as herbs that have been widely used in Vietnamese traditional medicines. However, studies on the effects of these plants in improving immune system of striped catfish (Pangasianodon hypophthalmus) have received less attention. Therefore, this study aimed to investigate the effect of ethanolic leave extracts from  P. guajava, P. amarus, and their mixtures (1: 1, v/v) on leukocytes of striped catfish (P. hypophthalmus). Leukocytes (5×106 cells/mL) collected from peripheral blood and head kidney were treated with P. guajava, P. amarus and their extracts combination at 2 different concentrations (10 and 100 mg/mL) for 24 hrs. The results showed that P. guajava, P. amarus and their extracts combination could stimulate positively to increased immune parameters. Specifically, lysozyme activity and total cellular Ig in treatments treated with extracts increased remarkably compared to the control (p

This study was to evaluate the effects of feed on growth and survival rate of scallop (Comptopallium radula Linnaeus, 1758) in planktonic larval stage, then to find algae replacement diet or artificial feed together algae to be more actively in feeding management in the hatchery. Veliger lavae were reared for 10 days to Umbo stage, with three different feed treatments (1):100% algae mixture of Pavlova sp., Chromonas sp. and Dicrateria sp. with ratio 1:1:1; (2): 50% algae mixture of Pavlova sp., Chromonas sp., Dicrateria sp. with ratio 1:1:1 + 50% artificial feed (Frippack, Lansy, dry algae Spirulina with ratio 1:1:1), and (3): 100% artificial feed (Frippack, Lansy, dry algae Spirulina with ratio 1:1:1). The results showed that the larvae in treatment 2 had the greatest shell height (189.3 µm) and shell length (192.3 µm). Day growth rate of length and height in treatment 2 are the highest but there was no significant difference with treatment 1. Larvae in treatment 1 had the highest survival rate, followed by treatment 2, whereas, treatment 3 had the lowest growth and survival rate and had significant difference with treatment 1 and treatment 2. Therefore, veliger larvae can be fed with fresh algae mixture or combined artificial feed at 50% to get good growth and survival rate.

The study was done through interviewing 110 nursing households and 38 trading households of hybrid catfish seed in Tien Giang province from February to October 2017 to assess the effectiveness such activities. The results of the survey of hybrids catfish seed nursing showed that the households groups with average nursing pond area 1,000-2,000 m2/pond (group I) and 2,001-3,000 m2/pond (group II) have higher productivity and profitability than the average nursing pond area 3,001-6,000 m2/pond (group III). The average nursing yields of the groups I, II, III were 939.0; 901.5 and 779.2 kg/1,000 m2/crop, respectively; the average profit of the three groups were 9.30; 8.93 and 6.79 million VND/1,000 m2/crop, respectively. Analyzing factors affecting yield showed that survival rates had the most significant effect on yield, while the average survival rate was gradually decreased in three groups I, II and III (28.3%, 25.5% and 21.7%, respectively). This suggests that appropriate management of nursing pond area is an important initial factor for the development of effective nursing practice. The results of the survey of hybrid catfish seed trading showed that the average profit of group A (retail) was 16.72 million VND/household/month, lower than group B (wholesale and retail) was 51.16 million VND/household/month, but the rate of profit of group A (20.89%) was higher than group B (7.66%). This shows that in order to achieve a large scale of business and profit, hybrid catfish seed traders need a large capital cost and accept a reasonable profit margin to develop the market. Title: Assessment the effectiveness of hydrid catfish seed (Clarias macrocephalus x C. gariepinus) nursing and trading in Tien Giang province.

The study was carried out to examine the pathogens on white clams (Meretrix lyrata) in Ben Tre province from February to December 2016. The results showed that clam in mortality events revealed pale digestive gland, yellow meat and trapped sand in body cavity. The environmental parameters such as pH, NO2, NH3, H2S showed no difference between the dry and rainy seasons, whereas, significant differences in temperature and salinities between these two seasons were recorded (p

The study is aimed to investigate the analytical methods for total volatile bases nitrogen (TVB-N) determination applied for seafood products freshness evaluation. The investigated methods included (1) the use of perchloric acid for TVB-N extraction followed by distillation with sodium hydroxide, ammonia absorption by boric acid and titration by hydrochloric acid (TCVN 9215 - 2012) and (2) the use of hot water and magnesium oxide during distillation, ammonia absorption by boric acid and titration by sulfuric acid (Velho, 2001). Freshness of fish was evaluated under cool storage. Marine fish samples in local markets and super markets were also collected for freshness evaluation. Results showed that both methods are applicable for freshness determination, represented through high recovery, good repeatability and the low coefficient of variation. Striped catfish and round scad were still fresh after three days of storage in ice. Marine fish (round scad and mackerel) collected in local market and super market in Can Tho city showed the premium freshness quality. Thus, the TVB-N determination method using hot water and magnesium oxide during distillation, absorption by boric acid and titration by sulfuric acid (Velho, 2001) can be used for routine analysis of the fish freshness due to less use of toxic chemicals compared to standard method TCVN 9215 – 2012.

Effects of stocking density on water quality, growth and survival of bighead catfish (Clarias marcocephalus) reared in a recirculating system were studied for 12 weeks. Fish with initial body weight of 10.01±1.01g were stocked at 4 densities of 40, 60, 80 and 100 fish/100-L tank. Fish were fed twice a day at adlibitum rate with 41% protein pellet. During the experiment, pH of all treatments ranged from 6.03 to 8.67 and tended to decrease with the increase of feed amount and densities. TAN, NO2- increased in a first few weeks and decreased in following weeks. NO2- ranged from 0.02 to 1.28 mg/L. Generally, water quality parameters were in suitable ranges for fish growth. Treatment 100 fish/100L gave the best results with specific growth rate of 2.56 %/day, survival rate of 83%, productivity of 97.39kg/m3, and feed conversion rate of 1.2. Further studies on higher stocking densities and larger scale were recommended for detemining optimal density and financial efficiency for application to commercial production.

The study was conducted during one-year cycle, with six sampling periods in January, March, July, September and November 2015 to identify the phytoplankton and dissolved oxyen (DO) fluctuations at the Nhieu Loc - Thi Nghe (NL-TN) canal in spatial, temporal and tidal scales, thereby proposing solutions to manage the fish stock in the canal. The NL-TN canal is devided into three sections including downstream, midstream and upstream, with nine sampling stations. The collected samples represented the highest and lowest tide periods of the month. The results showed that the phytoplankton biomass reached highest value in upstream (5,2-6,1 gDW/m3) and lowest in downstream (4,4-4,9 gDW/m3); however, there is no correlation between high biomass phytoplankton and low DO in early morning in spatial scale. In terms of temporal aspect, phytoplankton biomass reached the highest in July (6.9 gDW/m3) and the lowest in September (3.5 gDW/m3); however, there is no correlation between phytoplankton and DO biomass over time. Therefore, the monitoring of phytoplankton biomass with the frequency of 2 months/time is not effective in predicting correlative fluctuations of phytoplankton indicator with DO deficiency for fish stock management. Considering tidal fluctuations, high and low tide levels had significant influence on the annual average phytoplankton biomass difference. Considering the DO aspect, DO shows the lowest level in the early morning of May at the low tide period, which coincides with the high mortality of fish stock in the canal at the beginning of the rainy season, posing a requirement for DO monitoring and management at the risky times with DO deficiency for fish stock management.

The sakae naa (Combretum quadrangulare) which has long been regarded as a precious herb, can cure many diseases in human and aquatic animals. The extracts from its leaves and seeds using cold soaking in ethanol and heated extract method, were evaluated on anti-microbial activities in vitro against pathogenic bacteria such as Aeromonas hydrophyla, Edwardsiella ictaluri and Vibrio parahaemolyticus. The results showed that the three pathogens were inhibited by sakae naa extracts with the diameter of bacteria-free halos of 5.3 mm, 8.98 mm, and 6.25 mm, respectively. The extracts obtained by heated method showed higher anti-bacterial activity compared to those obtained by ethanol solvents. The MIC (minimum inhibitory concentration) of leaves and seeds extracts against E. ictaluri was similar (16 μL/mL). The MIC of the seed extracts against A. hydrophila (12 ± 2.5 μL/mL) was lower than that of leaf extracts (28.8 ± 3.2 μL/mL). In the case of V. parahaemolyticus, MIC of the seed extracts (14.4 ± 1.4 μL/mL) was also lower than that of leaf extracts (21.6 ± 6.4 μL/mL). The findings from this study would provide essential elements in planning strategies for future sustainability of aquaculture by using herbs replacing antibiotics in treatment for aquatic animal diseases.

This study was carried out to determine the effects of three types of feeds (formulated feed, Spirulina flakes and combination of formulated feed and Spirulina flakes) on the breeding and three induced methods (temperature, H2O2, ultraviolet light) on reproductive capacities of dog conch (S. canarium) bloodstocks in Khanh Hoa province. The results showed that the survival rate of the bloodstocks was highest at 92.11 ± 7.42 % in the treatment fed Spirulina flakes with no statistically significant difference found. The combinations of formulated feed and Spirulina flakes caused real fecundity (total egg weight) of bloodstocks that was the highest at 4.5 ± 0.27 g/female with the statistical significance higher than that in the treatment of formulated feed (2.9 ± 0.17 g/female), but non-significant difference was found in comparison with the treatments using Spirulina flakes as feed sources (4.16 ± 0.26 g/female). The feed type of combination of formulated feed and Spirulina flakes resulted that the hatching rate was the significantly highest at 94.1 ± 1.34 % in this experiment (p

This study was conducted from August 2017 to April 2018 through interviewing 90 eel culture households (45 households of VietGAP standard and 45 households of normal culture model) using prepared structured questionnaire with randomly sampling method. The aims of this study are to compare technical and financial efficiency between VietGAP model and normal culture model and to propose solutions to improve the efficiency of eel culture in An Giang province. The statistical description and mean comparison of quantitative variables (between these two models) using the Independent-Samples T-Test were applied to analyze the data. The results showed that the average culture area of VietGAP model is 104.2 m2/household and period culture of 274 days/crop, stocking density of 65.2 inds./m2 and yield of 7.9 kg/m2/crop. The corresponding figures of normal model are 97.5 m2/household, 243 days/crop, 58.7 inds./m2 and 6.6 kg/m2/crop, respectively. The total production cost of VietGAP standard model is 509.9 thousand VND/m2/crop, profit of 572.9 thousand VND/m2/crop and the gross profit ratio of 1.2 times. Whereas the production total cost of normal model was 525.5 thousand VND/m2/crop, profit of 470.6 thousand VND/m2/crop and the gross profit ratio of 1.3 times. The results show that eel culture VietGAP standard model was effective more than eel normal culture model but the difference was not statistically significant (p>0.05). Difficulties in eel production are unstable market price and high investment cost.

Acute hepatopancreatic necrosis disease (AHPND), also called early mortality syndrome (EMS), is a recently emergent shrimp bacterial disease. The causative agent of AHPND is specific strain Vibrio parahaemolyticus, and it severely damaged the intensive and semi-intensive shrimp farming systems. The bacterial strain Bacillus licheniformis (B1) isolated from the intestine of Mugil Cephalus in nature showed the antagonistic properties against pathogenic strain of V. parahaemolytics with 15 mm inhibition zone during 24 hours. In addition, the anti-V. parahaemolytics activity tested by co-cultured method demonstrated that the concentrations of strain B1(105 CFU/mL, 106 CFU/mL, 107 CFU/mL) might completely inhibit V. parahaemolytics (104, 105, 106, 107 CFU/mL) after nine hours of co-culture and this inhibition activity of the strain B1 was stable up to 24 hours.

In this study, gelatin has been successfully extracted from Tra catfish skin in different storage conditions (fresh, frozen one month and three months) to evaluate the effect of frozen storage condition of raw material on the quality of gelatin product. All the three skin samples of Tra catfish were soaked in NaOH solution with the concentration of 0.1M for 30 minutes and CH3COOH solution with the content of 0.07M for 3 hours to remove the noncollagenous protein and demineralization, respectively. Gelatin extracted in water at 70°C for 1.5 hours was obtained the highest viscosity and extracted yield with values of 6.55 mPas, 13.5%, respectively for the sample fresh skin, 6.57 mPas, 16.6% for the sample frozen one month and 5.39 mPas, 16.2% for the sample three months. Optimum condition for drying gelatin of the three samples skin of fish is 55-60°C for 22h. The gel strength of gelatin was extracted from fresh, frozen one month and three months of Tra catfish skin is 166; 154 and 151 g and higher than 2 times when compared with commercial gelatin (75.3 g). The results from this study showed that quality of gelatin products is not affected by storage time.

The study is aimed to determine the stocking densities for the growth and survival rate in mud crab larvae nursing from zoae1 to crab 1 (C1). The study included two experiments: (1) the mud crab larvae nursing from zoae1 to zoae4 at different of stocking densities (300, 350, 400 và 450 inds/L) and (2) the mud crab larvae nursing from zoae4 to crab1 (C1) at different of stocking densities (40, 50, 60, 70, 80, 90 and 100 inds/L). The experiments were completely randomized with 3 replications. The tank volume was 100 L and salinity water was 30‰. The result of the first experiment showed that, after 10 days of nursing, the metamorphic rate of zoae4 stage were 100% in all treatments. The larvae stage index (LSI) and growth in length were not significant difference between treatments (p>0.05). The survival rate of zoae4 ranged from 57.2 to 64.4% and no significant difference (p>0.05) was found among treatments. The result of the second experiment showed that after 16 days of rearing, the growth in the length and LSI were not significant difference between density treatments (p>0.05). The survival rate of C1 in treatments ranged from 4.8 to 9.4%, and they were significant difference among treatments (p0.05), but it was significant difference with higher stocking densities (80, 90 and 100 inds/L). These results indicated that nursing from zoae1 to zoae4 stage at stocking density 450 inds/L and from zoae4 to C1 at 70 inds/L showed the best growth performance and survival rate in mud crab larvae rearing.

The study was aimed to determine the effect of salinity, density and suitable partial harvesting strategy to obtain high and stable Artemia franciscana biomass production that could contribute to actively providing Artemia biomass for aquafeed in hatcheries. The combined effects of salinity and stocking density on growth, survival and Artemia biomass production were assessed in tank conditions. The experiment consisted of nine treatments with two factors (salinity and stocking density), the combinations of three salinity levels (15; 30 và 45‰) and three stocking densities (500; 1,000 and 1,500 Ind./L), each treatment had three replicates (Experiment 1). This experiment was using formulated feed with 30% of protein and 9% of lipid  for 14 days. The best results were obtained that total length (6.2 mm) and biomass (1.31 kg/m3) at salinity of 30‰ and stocking density of 500 Ind./L. Based on such results, the experiment 2 on partial harvesting strategy was setup with three replications of nine treatments combining three harvest intervals (1, 3 and 5 day interval) and three different harvesting percentage of Artemia biomass (Artemia adult) (10, 20 and 30%). The results of the experiment 2 indicated that the application of everyday partial harvesting of Artemia biomass with different fractions obtained higher yields than that of other harvesting treatments, of which harvesting at 30% every day gave highest biomass productivity (2.20 kg/m3) after five weeks of culture.

Species of the genus Moina (Baird, 1850) often dominate the freshwater crustacean communities. Some species of Moina are used as food for fish larvae in aquaculture and as biological indicators in toxicological studies in aquatic environments. This study is aimed to investigate the species diversity of Moina spp. in the Mekong Delta region (An Giang, Dong Thap, Can Tho, Ben Tre and Long An province) by morphological analysis method and DNA barcoding method based on the mitochondrial cytochrome coxidase subunit I (mtCOI) gene sequence. Fourty eight Moina sp. specimens from this study were successfully sequenced their mtCOI genes. Five groups of Moina sp. were identified in 48 specimens examined, and the occurrence frequency of M. micrura was higher than that of M. macrocopa. The results revealed that 4/48 Moina sp. specimens belonging to group V showed 99% nucleotide similarity with M. macrocopa, whereas 31/48 specimens of group I exhibited 99% nucleotide similarity with M. micrura. Meanwhile, the mtCOI gene sequence divergence of group II (8/48 specimens), group III (4/48 specimens) and group IV (1/48 specimen) were more than 10% in comparison with the Moina mtCOI sequences published on National Center for Biotechnology Information (NCBI) Genbank®.

This study aimed to evaluate the effect of supplemented garlic on the immune system and disease resistance of Red tilapia (Oreochromis sp.). Experiment was randomly designed with 5 treatments and triplications for each treatment. The treatments were 0.5 and 1% garlic; 0.25 and 0.5% garlic powder and control treatment. After 14 days of feeding garlic, fish were challenged with bacteria (Streptococcus agalactiae). Sampling was conducted after the fish were fed feed containing garlic for 7 days, 14 days and after 3 days of infection with Streptococcus agalactiae. Several immune parameters including the total erythrocyte cells, leukocyte cells, each type of leukocyte and lysozyme activity were observed.. The results showed that hematology parameters and lysozyme activity in garlic supplemented treatments were significantly higher than those of control treatment (p

The study determined the effects of the Apex Aqua on growth and survival of spotted scat to find the appropriate rate of Apex Aqua supplements to enhance growth and survival of spotted, scat contributing to improving effective culturing procedures and reducing production costs.. The experiment was designed randomly with four treatments with different ratios of Apex Aqua, including (1) no fertilize, (2) fertilize at the rate of Apex Aqua = 2 g/m3, (3) fertilize at the rate of Apex Aqua = 4 g/m3, (4) fertilize at the rate of Apex Aqua = 6 g/m3. Each treatment, was repeated three times. Spotted scat was 0,15 g in average weight, and was cultured at  salinity of 5‰; Apex Aqua was supplemented every 3 days. After 45 days of experiment, water factors were suitable for the development of spotted scat. Spotted scat in the treatment of Apex Aqua = 2 g/m3 (the everage weight gain of 1,267 (g), daily weight gain of 0,025 g/day and relative growth rate of 4,613 %/day) showed the highest figures, and difference was statistically significant (p0,05) compared with the other treatments. Thus, spotted scat can be cultured with fertilize at the rate of Apex Aqua = 2 g/m3.

The study was conducted from August to December 2017 through interviewing 30 inshore gill net households (

This study was conducted to investigate the susceptivity of bacterial pathogens Aeromonas schubertii causing white spot disease on snakehead fish (Channa striata) in intensive ponds in Tra Vinh province. All 24 isolates were tested for physiological, biochemical indicators before proceeding antibiotic susceptibility with 15 antimicrobial agents. Then 4 representative isolates were chosen to determine the minimal inhibitory concentration (MIC) with 4 antibiotics (colistin, doxycycline, erythromycin, amoxicillin) by method with broth dilution. The results showed that A. schubertii was highly susceptible with doxycycline (83,33%) and colistin (79,17%), highly resistance to oxytetracycline (79,17%), florfenicol (79,17%), erythromycin (70,83%) and novobiocin (62,5%). A. schubertii isolates showed fully resistant to ampicillin, amoxicillin and rifampicin. The results from determining the MIC values showed that 4 isolates were highly susceptible to colistin (MIC = 0,25-0,5 μg/mL) and doxycycline (MIC = 4 μg/mL), resistant to erythromycin (MIC = 8 μg/mL) and fully resistant to amoxicillin (MIC = 512 μg/mL).

The study is aimed to find the suitable period of adding carbohydrate from molasses for growth and survival of black tiger shrimp larvae and postlarvae. The experiment included four treatments (i) Carbohydrate supplementation from Mysis-1, (ii) carbohydrate supplementation from Mysis-3, (iii) carbohydrate supplementation from Postlarvae-2, and (iv) carbohydrate supplementation from Postlarvae-4. Density of 150 larvae/litters was stocked in 500-litter experimental tanks with salinity of 30‰, and molasses were applied to the tank with C/N ratio of 25. The results of the experiment showed that the environmental factors, bacterial density, bioflocs during rearing were appropriate for the development of larval and postlarval tiger shrimp. The better growth in length of Postlarvae-15 was obtained in the treatment where carbohydrate was added to the culture from Mysis-3 as compared to the rest treatments (p>0.05). The survival rate (68,25±11,19%) and productivity (88,7± 14,45 inds/L) of Postlarvae-15 were highest in the culture where carbohydrate was added, no significant was found (p>0.05) when compared to the culture where carbohydrate was added from Postlarvae-2, but there was significant difference (p

The study is on using Supa-stock® to stimulate growth of live food of phytoplankton and zooplankton rearing ponds and increase feed catching ability and growth of pangasius catfish fry. The experiment was conducted with 3 treatments including control (no Supa-stock®), 2 days before stocking, and 4 days before stocking. Three replications were set up for each treatment. Application of Supa-stock® was implemented every day to day 10 after stocking. The area of experimental ponds was 2,500 m2, water level of 1.3 m. Stocking density was 106 fries/1000 m2. Quantitative and qualitative samples of zooplankton were taken every day until day 10 to detemine zooplankton species composition and densities in the ponds. At the same time, fry samples were also collected to determine their feed composition and selection in the gut. The results showed that 65 zooplankton species were found belonging to four groups including Rotifera (27 species), Copepoda (20 species), Cladocera (13 species), and Protozoa (5 species). The zooplankton densities were in a range of 118,148 - 5,777,037 ind./m3 in which Rotifera was the most abundant group with high densities ranging from 50,926 - 3,788,889 ind./m3. Lowest density (0 to 32,593 ind./m3) was recorded for Protozoa. Feed selection of catfish in the treatment with Supa-stock® supplement 2 days before stocking was significantly (P

In this research, the morphological characteristics of “strange” catfish phenotype (Phu Quoc, Kien Giang) were compared with Clarias species, including Clarias cf. batrachus, C. macrocephalus and C. gracilentus to provide information on speices composition of Clariidae in Phu Quoc island. Total 129 samples were collected and analyzed based on ratios of 22 biometric indices with standard length or head length. In external morphology, the four catfish groups can be distingushed by body shape, color, head structure and pectoral spine pattern. The “strange” catfish group is well recognized because the serration of pectoral spine can be observed. All biometric indices are significantly different among four fish groups (p< 0.05). Principal Component Analysis- PCA analysis also shows that the four Clarias groups are divided into four clearly clusters, in which, the “strange” catfish is relatively closer to C. macrocephalus compared to the other groups. The two principal components (PC1 and PC2) explain 46.3% and 22.6%, respectively, of total morphological variation among the four groups. Based on discriminant analysis, all individuals can be classified into their original group with 100% probability of correct assginments. The results from this study support a previous finding that “strange” catfish may not be a hybrid between C. macrocephalus and C. gracilentus.

This study was carried out to determine possible effects on the susceptibility of black tiger shrimp (Penaeus monodon) to Vibrio parahaemolyticus when the shrimp were co-cultured with red seaweed (Gracilaria sp.) and fed withdifferent feeding rates. After a 60-day experiment, experimental shrimp was examined the total haemocyte count (THC), the differential haemocytecount (DHC), phenoloxidase (PO)activity and disease resistance toV. parahaemolyticus. The results showed that (i) THC, DHC and PO significantly increased in the co-culture treatments; and (ii) the cumulative mortality percentage at 14 days post-infection (dpi) was much lower in the co-culturing treatments (23.3%) than that in the control treatment (63.3%). The results demonstrated that co-culturing black tiger shrimp with red seaweed andvariation of feeding rate can induced the immune responses andthe survival of P. monodon that was challenged with V. parahaemolyticus.

The development of digestive system on morphology and histological structure of Clarias gracilentus was investigated from 1st to 30th day after hatching (DAH). The larvae opened buccopahrynx at the second DAH, but they started exogenous feed at the 5th DAH with average buccal size being 0,89±0,05 mm. The digestive tract was devised 4 parts including buccal capacity, oesophagus, stomach, and intestine.  At the 10th DAH, the stomach had digestive function. For histology of digestive structure, the stomach was formed at the 5th DAH but was completely developed at the 10th DAH with the appearance of several gastrics. Clarias gracilentus was nursed with plintery feed from the 10th (10 days after hatching – DAH), but the growth (0.003 g/day) was significantly lower than those  feed with commercial pellet at the artificial from 16th and 19th DAH (0,004 and 0,005 g/day, respectively) (p

The study on the fishing activities of trawlers and gill nets was conducted from March to December 2017 in Soc Trang province. The results showed that the trawlers and gill nets had the highest number of fishing boats. The fishing season of trawlers and gill nets are all year round. There was no significant difference between capacity of gill net boats (37.5 CV) and trawler boats (38.9 CV) (p>0.05). The yield and ratio of trash fish of gill nets (14.1 tons/year; 15.1%) were lower than those of trawlers (17.7 tons/year; 45,2%) (p

This study was conducted to evaluate the effects of inulin and fructooligosaccharides (FOS) on the growth performance and immune system of stripped catfish fingerling (Pangasianodon hypophthalmus). The experiment was randomly designed with 5 treatments (control, 0.5% Inulin, 1% Inulin, 0.5% FOS, and 1% FOS) and triplications for each treatment. After 21 and 28 days, several immune parameters including total erythrocyte cells, total leucocyte cells, number of each type of leucocytes and lysozyme activity were analyzed for evaluating of fish immune response. After 28 days, fish was weighted for estimation of growth performance and was challenged with pathogen (Edwardsiella ictaluri) for evaluating of bacterial resistance. Fish mortality was recorded daily for 14 days. After 3 days of infection with E. ictaluri, 3 fish in each tank were collected for immune assay. The results showed that hematological parameters and lysozyme activity of inulin and FOS supplemented treatments were higher than those of the control treatment after 28 days. The treatment of 1% inulin showed that the total number of leukocyte, monocyte, neutrophil, lymphocyte, thrombocyte and lysozyme activity were significantly higher than those of the control treatment after 28 days and the lowest mortality (42.67%) after challenge with E. ictaluri (p