The study was conducted to determine the effect of extract from chamber bitter (Phyllanthus amarus) on the quality of cobia fillet during ice storage. Cobia fillets (16 pecies; 800-1200 g) were soaked in ice cold water (≤ 4 ) for 30 minutes, drained then packed into PE bags and stored in the insulated box with ice, using as control treatment. In the Phyllanthus amarus treatment, 16 fillets were soaked in extract of chamber bitter 0.02% for 30 minutes and preserved in the same way as control treatment. Sampling was done at 1st, 5th, 10th and 15th day of storage time. Evaluated parameters included pH, temperature, texture, sensory property, total volatile base nitrogen, color, moisture, total aerobic bacteria count, peroxide value and TBARs water holding capacity, the change of color and moisture of fish fillet. Results showed that cobia fillet in both of treatments kept quality and safety for 10 days of ice storage. The use of chamber bitter extract showed the better sensory property (7.96) and significant lower total aerobic bacteria count (4.24 log10 CFU/g) compared to the control treatment (7.00; 4.89 log10 CFU/g) after 10 days of storage. Total aerobic bacteria count at the 15th day exceeded the limit 106CFU/g.

The study was conducted to evaluate the susceptibility of striped catfish (Pangasianodon hypophthalmus) to Edwardsiella ictaluri, a causative agent of Bacillary necrosis disease, at different salinities. Experimental striped catfish (25 ± 0.8 g/fish) were randomly stocked at the density of 20 fish/tank (60L in volume) containing freshwater (0ppt) and constant aeration. Salinities in experimental tanks (by a group of 18 tanks) were adjusted to 3, 5, 8, 11 and 14ppt. Seven days after being acclimated to different salinities, fish were challenged by injecting with E. ictaluri. After 14 days of post challenge, fish in salinities of 11 and 14ppt were more susceptible to E. ictaluri with significantly higher cumulative mortality compared to fish in lower salinities (P

This study was aimed to compare morphological characteristics of striped dwarf catfish (Mystus mysticetus) distributed in U Minh Thuong with other populations in the Mekong Delta. Fish specimens were collected in An Giang, Can Tho, Dong Thap and U Minh Thuong - Kien Giang provinces (47- 70 individuals/ population). Morphological characteristics including meristic traits (number of spines and rays of fins, gill rarkers in the first arch) and morphometric indices (ratios to standard length or head length) were analyzed to test variations among populations and between sexes. Results showed meristic traits are identical among populations. Conversely, 22/23 morphometric indices vary significantly (P

Study on co-culture of the black tiger shrimp (Penaeus monodon) and red seaweed (Gracilaria tenuistipitata) at different densities in the net pen placed in pond was carried out in Bac Lieu province. A two-factor experiment was set up with three stocking densities (2, 4 and 6 ind./m2) in combination with two culture system (i.e. co-culture and mono-culture), each treatment was in triplicate. Shrimp with mean initial weight of 1.07 g was stocked in the net pen (16 m2) without feeding condition. After four months of culture, growth rate, survival and production of shrimp in the co-culture group were significantly higher (p

Studying on fishing status and perception of fishermen on the impact of climate change to near shore bag-net fishing at Soc Trang province was performed from January to June, 2018. Results showed that fishing boat power, length, and tonnage are recorded at 32.7±13.9 CV; 12.09±1.63 m; and 5.46±3.97 tons, respectively. Bag-net length, width, height, and cod-end mesh size are at 23.3±7.97 m; 14.2±5.02 m; 5.35±2.71 m; and 2a=12.7±0.46 mm, respesctively.  The average member of fishermen is 3.63±1.56 people/boat; 47.9±13.7 years old; 80,0% at primary school level in education. The average of fishing time is 6,2±3,1 days/month and the main fishing season is from January to June annually. Fishing yield is at 191.9±152.8 kg/day/household (11.9±10,0 tons/year/household). Total investment cost is at 124.1±54.1 million VND/boat and variable cost at 1.36±0.79 thousand VND/household/day. Turnover is at 2.24±0.88 million VND/day and profit rate 0.53±0.47.  There are 77.5% fishermen only working on fishing. There are 55% fishermen have aware of climate change such as stronger wind rate and increasing storm frequency, and fishing season present unusually and difficult to predict. Only 45% fishermen have some temporary solutions to cope with climate change. Generally, bag-net fishing have low production and unstable income due to extreme weather and banning regulation. Thus, the fishermen suggest suitable and integrated solutions for their better livelihood.

This study was carried out to determine the effects of extracted herbs as anti-fungal agents on Achlya sp. and Saprolegnia sp. The antifungal activity, minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of five herbs including Chromolaena odorata, Achyranthes aspera, Carica papaya, Perilla frutescens and Muntingia calabura were examined for snakehead pathogenic Achlya sp. and Saprolegnia sp. The result indicated that extract of Perilla frutescens showed antifungal activity higher than those of the remaining herbs. MIC and MFC of Perilla frutescens showed the most effective against to both fungal hyphae and zoospore of Achlya sp. and Saprolegnia sp. in 1.6 mg/mL at 24 h exposure. Chromolaena odorata and Achyranthes aspera exhibited antifungal activity to hyphae and zoospores at concentrations of 3.2 mg/mL. The hyphae of Achlya sp. and Saprolegnia sp. were grown when they were exposed to 100, 50, 25, 12.5 and 6.4 mg/mL of Carica papaya solution.

The aim of the study was to investigate the effect of rosemary (Rosmarinus officinalis) extract on the quality changes of fish balls during chilled storage. Rosemary extract were supplemented into fish balls at two different concentrations of 13 mg/kg and 156 mg/kg. The control treatment was the sample without extract. All samples were steamed, vaccum packed in PA bags and stored in refrigerator during three weeks. Sampling was done every week for analysis of pH, total viable count (TVC), sensory properties, peroxide value (PV) and Thiobarbituric acid reactive substances (TBARs). Results showed that adding rosemary extract of 156 mg/kg in fish balls could improve sensory quality, TVC as well as inhibit lipid oxidation when compared to other treatments. The quality of fish balls could be maintained in terms of microorganism and organoleptic until two weeks.

This study was conducted from 12/2017 to 02/2019 to provide the population biological parameters of the many-fingered grenadier anchovy, one of the commercially valuable fish, for sustainable use of the fisheries resources in Cua Lon river, Ca Mau province. The analysis of length-frequency data of 2,196 individuals collected every two months by using push net showed that the von Bertalanffy curve and growth performance were Lt=16.8×(1-e-0.68×(t+0,28)) and F’  = 2.28, respectively. The total mortality (Z), natural mortality (M), fishing mortality (F) of this species was 2.28 yr-1, 1.68 yr-1, 0.60 yr-1, respectively. The exploitation rate (E=0.260) was lower than that of the potential exploitation rate (E50=0.342). The length at first capture was Lc = 7.0 cm; there are two recruitment peaks per year (in July and November). Although this species has high growth rate and its population still has higher potentials for exploitation, the length at first maturity was small. Therefore, mesh sizes of the push net should be increased for sustainable use of the fisheries resources.

The study was conducted to investigate the variation in density of Bacillus spp. bacteria in water and mud in My Thanh river, including the upper stream (Nhu Gia), middle stream (My Thanh 1), and lower stream (My Thanh estuary = Mỹ Thanh2). Samples were collected once a month from July 2017 to June 2018 at low tide. Bacteria density was determined by heating method (80⁰C in 30 minutes) before plate on Bacillus selective medium. The results showed that the density of Bacillus bacteria in water and mud ranged from 7,1×101- 5,4×103 CFU/mL and 8,1×103 -1,6×106 CFU/g respectively. Bacillus density was highest in upper straem and lowest in low stream during sampling period. In general, the trend of Bacillus density in water and mud were ranged in the upper stream and stable at the lower stream. The density of Bacillus in water and mud tends to decrease as salinity increases, this is probably due to the highest upstream organic matter content compared to the other two sampling site, so it may helps to Bacillus bacteria to develop best.

Sand lobster (Thenus orientalis) is one of the lobster species with high commercial values and important seafood product for exporting to the international markets. Specimens were collected monthly from October 2017 to September 2018 at Nam Du island, Kien Giang province to investigate the gonadal development and spawning season. A total of 249 sand lobsters was collected and the results showed that the sexual ratio and the size of this species were high variation, in which the females were always larger size than male. The appearance color and size of ovary were changed during the gonadal development in females, however, those characters were not evident in males. Findings showed that a high proportion of spawning females was presented in February (53.6 %), May (60.0 %) and September (53.8 %). The largest sizes of oocytes were also recorded in those months with corresponding numbers of 113.9 ± 11.8 µm; 146.0± 15.2 µm and 149.6± 12.9 µm.  The results of this study could contribute primary information on the productive biology and spawning season of sand lobster to support resource management and artificial seed production.

The study was conducted to interview 60 whiteleg shrimp farms in Duyen Hai and Cau Ngang districts, Tra Vinh province. The aims of this study were to investigate the drugs, chemical use and common diseases in cultured whiteleg shrimp (Litopenaeus vannamei). Results showed that white feces syndrome occurred in both of shrimp farming systems (earthen ponds and plastic-lined ponds) with the same ratio of 56.6%. Red body syndrome was recorded at the percentage rate of 40% in earthen ponds and 3.3% in plastic-lined ponds. Acute hepatopancreatic necrosis disease appeared differently in earth pond and plastic-lined ponds with ratios of 26.6% and 36.6%, respectively. The common antibiotics were cotrim (23.3%), amoxcillin (20%) and ciprofloxacin (13.3%). Most of the interviewd shrimp farmers applied probiotics in their shrimp ponds with such common microorganism species as Bacillus subtilis, B. licheniformis and B. megaterium. The obtained results showed the need to provide training to shrimp farmers to guarantee for the safety of aquatic products.

Hydroxyapatite (HA) is a calcium phosphate mineral that exists in animal bones and it has good biological compatibility. Therefore, this study was conducted to produce hydroxyapatite (HA) from striped catfish (Pangasianodon hypophthalmus) bone. After pre-treatment in dilute NaOH solution and ethanol, the striped catfish bone was calcined at high temperature to burn all organic compounds and then grinded by ball mill machine to obtain powder of striped catfish bone. The powder was used to react with H3PO4 solution to produce HA. Some important factors affecting HA formation such as concentration of H3PO4, reaction temperature, pH value, calcinating time and temperature were investigated. Experimental results showed that it could be produced HA in crystal size of 100 nm and particle size of 1,100 nm when reaction was carried out in solution of H3PO4 60 mM, reaction temperature 90 ℃, pH 11 and calcinating at 1,000℃ in 2 hours. Hydroxyapatite (HA) là một loại khoáng calcium phosphate tồn tại trong xương động vật và có tính tương hợp sinh học tốt. Vì thế, nghiên cứu được tiến hành nhằm sản xuất hydroxyapatite từ xương cá tra (Pangasianodon hypophthalmus). Sau khi được xử lý với dung dịch NaOH loãng và cồn, xương cá được nung ở nhiệt độ cao nhằm loại bỏ các hợp chất hữu cơ và được nghiền thành bột bằng máy nghiền bi. Bột xương cá sau đó được chuyển hóa thành HA. Các yếu tố ảnh hưởng đến sự hình thành của HA như nồng độ H3PO4, nhiệt độ phản ứng, pH dung dịch phản ứng, nhiệt độ nung và thời gian nung HA được tiến hành khảo sát. Kết quả cho thấy, có thể sản xuất HA dạng hạt với kích thước tinh thể khoảng100 nm và kích thước hạt khoảng 1.100 nm khi phản ứng chuyển hóa bột xương cá được thực hiện ở điều kiện H3PO4 60 mM, nhiệt độ phản ứng 90℃, pH 11 và nung ở 1.000 ℃ trong thời gian 2 giờ.

This study was conducted to evaluate the effects of different temperatures on growth performance, survival rate and digestive enzyme activities of mud crabs (Scylla paramamosain) juvenile (C1). The study was conducted with four temperatures (27-28℃; 30-31℃; 33-34℃ and 36-37℃) in 200-L tankswith water salinity at 25 ppt. The growth performance of crab (carapace wide – CW and body weight - BW) at 27-28℃ treatment was significantly, lowest (p

This study aimed to evaluate the effect of dietary chamber bitter (Phyllanthus urinaria) extract on the resistance to Bacillary Necrosis in Pangasius (BNP) in striped catfish (Pangasianodon hypophthalmus). The experiment was in the completely randomized design with 3 triplicated treatments including 0% (control); 1% and 2% of P. urinaria extract. After 4 weeks of experimentation, fish were injected with Edwardsiella ictaluri. Samples were collected in the week 2nd and 4th of experiment and  day 3rd of challenge test for immune parameter test. Fish mortalities among treatments were also recorded. The results showed that ecrythrocytes, leukocytes, monocytes, lymphocytes and lysozyme activity were significantly increased in supplemented P. urinaria treatments if compared those of the control (p

Density and size of planktonic organisms had significant influenced on survival rate (SR) of striped catfish Pangasianodon hyphophthalmus at first feeding. Maintaining zooplankton density of 5-7 ind./mL and algae density of 0.15-0.3 million cell/mL, the highest SR (30.1±5.7%) achieved at rearing density of 5 fish/L (5 times higher than larval density in earthen ponds). Survival rates were influenced (p

The study was conducted in the estuaries of the Cua Lon and Bay Hap, Ca Mau province, from August 2017 to June 2019 in order to determine the species composition and distribution characteristics of croakers. Samples were collected bimonthly by using push nets (totally 12 sampling times). The salinity in the investuagted areas ranged between 25-28 ‰ (Cua Lon River) and 21-25 ‰ (Bay Hap River). The results showed that ten species of croakers (Sciaenidae) were identified in which the fish species composition in Cua Lon is more diverse than in Bay Hap. The croaker species are widely distributed during rainy and dry seasons at all sampling sites. In Bay Hap river, the CPUE of croaker tends to decrease from inland to the estuarine areas, with 5.2 g.ha-1 to 0.05 g.ha-1, where the most abundant areas are in Cha La (3.3 g.ha-1) and Bay Hap (2.79 g.ha-1) in both seasons. In Cua Lon river, the abundance tends to increase gradually from inland to the estuarine areas (2.89 - 27.66 g.ha-1). In the rainy season, the highest abundance of croakers is at the sampling site Sa Pho with 31.16 g.ha-1and the lowest one is at Ong Trang site (0.12 g.ha-1).

The aim of study was to investigate the seasonal variation of phytoplankton in the estuary of Hau river, Soc Trang province. Phytoplankton samples were collected once a month at high tide and low tide in three sites during for 12 months (form July, 2017 to June, 2018). The results showed that a total of 221 species of phytoplankton were identified, in which 97 species (44%) were diatom (Bacillariophyta), 54 species (24%) were green algae (Chlorophyta), and 16-35 species (7-16%) belonged to other phyla. Species composition of the phytoplankton in the dry season was more diverse than that of in the rainy season. Species number of phytoplankton at high tide was higher than that of at low tide. Diatoms were always the most abundant in all samplings. Mean density of phytoplankton in the rainy season and dry season ranged from 49,595±14,542 to 83,246±29,639 ind/L and from 57,745±37,505 to 109,105±78,261 ind/L, respectively. The diatoms were found to be dominant in all sampling locations. Significant correlation was not observed between temperature or pH and phytoplankton composition in the estuary of Hau river. There were significant positive correlations (p

A study on the nutritional characteristics of Soldier croaker Nibea soldado (Lacepède, 1802) was conducted from January to June 2019 in coastal areas from Soc Trang to Ca Mau provinces. Fish samples were collected monthly by trawl-net (engine capacity of 70 CV) with two  groups of sizes such as juvenile (total length of 114-170 mm- small fish) and adults (total length of 209-370 mm- big fish). The results showed that the fish have wide mouth, long mouth and slanting; the jaw is very developed; gill rakers were sparse, short and hard to hold feed; esophagus was short, thick wall, with many folds; stomach was greatly expanded with the posterior portion, forming as a long sac, thick wall and many folds inside; caeca has 8-9 tubes with a sealed end attached to between the stomach and intestines; intestine was short, thick wall and folded in S-shape. Relative length of the gut (RLG)

A study on rearing spotted scat (Scatophagus argus) in earthen ponds at different stocking densities was aimed to determine appropriate stocking densities for growth performance and survival from fry to fingerling stages. The experiment was randomly desgined in duplicate with three stocking densities including 10, 20 and 30 ind/m2. Each earthen pond had an area of 100 m2 and water salinity was 15‰. The fry were initially recorded at 0.11 ± 0.02 g of body weight and 11.2 ± 0.1 mm of total length. After 56 days of rearing, the length and weight of fish in treatment 10 inds/m2 and 20 inds/m2 were significantly higher than those of fish in treatment 30 inds/m2 (p

The study was conducted to evaluate the antioxidant and antimicrobial of green tea extract on the quality of red tilapia paste under cold storage condition. The experiment consisted of three treatments. green tea extract at different concentrations as 0% (control treatment), 7.63 mg/kg and 625 mg/kg was mixed with mined fish meat. The mixture was minced, paste forming, steamed for 10 minutes and cooled at room temperature. Each treatment included 80 samples (20 g/sample), divided into 4 PE bags and stored in refrigerator (

Acute toxicity and effects of quinalphos insecticide on activity of muscle cholinesterase (ChE) in post larval (Pl34) of giant fresh water prawn (Macrobrachium rosenbergii) were evaluatedin static non-renewable system for determiningLC50of quinalphos for postlarval and effects of sublethal concentrations of quinalphos on ChE of this species. Static non-renewable system was conducted to determine LC50. Effects of quinalphos at concentration of 1%, 10% and 20%LC50-96h on ChE were carried out for 48 hrs. Result showed that quinalphos was very toxic for post larval of Macrobrachium rosenbergii, LC50-96h was 0.69 µg/L. ChE activity in muscle tissue of this species was very sensitive to quinalphos; at the concentration far below the actual concentration in opened water bodies,quinalphos has already caused serious ChE inhibition for this species. ChE inhibition was highest at 24hrs exposure and reached 43.3%, 44.1%and 58.6% for concentrations of 1%, 10%and 20% LC50-96h, respectively. Quinalphos was very high acute toxicity for this stage of the species and muscle ChE is very sensitive to this pesticide.

The experiment was carried out to determine the antimicrobial activity of herbal extracts on the shrimp bacterial pathogens- Vibrio parahaemolyticus and Vibrio harveyi. Antimicrobial activity test, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) on pathogenic bacteria of herbal extracts were determined by disk diffusion methods and broth dillution methods. Results showed that: (i) the extract of Phyllanthus urinaria L., Punica granatum and Camellia sinensis showed the antimicrobial activity for both of V. parahaemolyticus and V. harveyi; (ii) the extracts of Cleome spinosa and Agerantun conyzoides were only inhibition of V. harveyi. Besides, the extracts of Thespesia populnea, Perilla frutescens, Chromlacna odorata, Carica papaya and Moringa oleifera did not show antibacterial activity to V. parahaemolyticus; (iii) The extract of Phyllanthus urinaria is determined to contain alkaloids, flavonoids, steroid and triterpenoids, reducing sugars, tanins and sesquiterpene lactones. In which, polyphenols content is 28.6 ± 0.9 mg GAE/g and flavonoids content is 341 ± 2.4 mg QE/g.

The aim of this study was to identify suitable carbon sources for the growth and survival of larvae of white-leg shrimp nursed in tanks with biofloc technology. The experiment was conducted with five treatments: (i) no carbon supplement (control), (ii) carbon supplement from wheat flour, (iii) carbon supplement from rice bran, (iv) carbon supplement from wheat and rice bran at a ratio of 50:50 and (v) carbon supplement from sugar. Each treatment was triplicated. The experimental tank was 500 liters in volume. Stocking density was 150 larvae/liter and water salinity was 30‰. Results of the experiment showed that the body length of 12-day old postlarvae (PL12) in the sugar treatment (10.18±0.15mm) was the highest and significantly different (p0.05) compared to the other treatments. The survival rate (52±5.1%) and productivity (78±8 larvae/liter) of PL12 in the sugar treatment were also the highest and significantly different (p

This study was conducted from January to December 2018 aiming to describe distribution channels and analyze added-value of fourfinger threadfin product caught by inshore gill nets in Bac Lieu province. The study data was collected by random interviewing of 70 fishermen operating inshore gill nets, 5 traders and 15 wholesalers of seafood products. The results show that fourfinger threadfin was distributed mainly by channel 1: Fishermen to Wholesalers to Export, which made up 67.6% of the total yield of fourfinger threadfin. In this channel, total value-added of the whole chain was 205.800 VND/kg, of which fishermen received 90.3% and wholesalers got 9.7% of total value-added. Fishermen created a profit of 173.800 VND/kg (accounted for 93.0% of the total) and profitability ratio was 3.8 times. Wholesalers made a profit of 13,000 VND/kg (made up 7.0% of the total) and profitability ratio was 0.06 times. In order to improve the efficiency of value chain of fourfinger threadfin caught by gill nets in Bac Lieu province, it is feasible to develop linkage across the chain aiming to share profits and risks in production.

This study was aimed to screen the strains of Lactobacillus spp. from the intestines of whiteleg shrimp, Litopenaeus vannamei that had probiotic properties for feed additives in intensive shrimp farming. One hundred and twenty whiteleg shrimp were collected from 12 ponds in Soc Trang, Tra Vinh, Bac Lieu and Ca Mau. Results showed that 141 strains were isolated from MRS agar. Results of the biochemical tests indicated that 23 selected strains were spherical, short rod shape; gram positive; negative for oxidase and catalase reactions. Ten strains, TV32, TV21, TV17, BL11A, DH5B, CM2B, DH3D, DH7D, DH9C, ST11, were selected based on the results of antagonistic activity and bacteriocin producing tests. These strains showed the inhibitory activity against pathogenic bacteria Vibrio parahaemolyticus with the average inhibition zone in a range of 7-11.5 mm, of which the TV32 strain showed the highest antagonist activity. Among these strains, TV32 was the strongest extracelluar enzyme activity, including protease, leu-aminopeptidase and a-amylase. Therefore, it was suggested that TV32 strain could be used for in vivo evaluations for development of probiotics for whiteleg shrimp culture.

Studying on fishing status and perception of fishermen on the impact of climate change to near-shore trawling net fishing at Soc Trang province was performed from January to June 2018 through interviewing 40 fishermen in three districts: Cu Lao Dung, Tran De and Vinh Chau. Results showed that averaged boat power, length, and tonnage are at 39.9±18.8 CV; 12.16±1.11 m; and 5.63±2.94 tons, respectively. Cod-end mesh size are at 21.2±7.0 mm. The average number of labors on boat is 2.98±0.95 people/boat (70.58% from family);  the average age of fishermen is at 45.7±11.2 years old;  the rate of fisherman education is at 77.5% under secondary school. Fishing season is year-round, but main fishing season is from April to July annually.  The average yield is at 9.3±6.2 tons/year/boat. Total investment cost for boat (including fishing gear) is at 117.62±59.57 million VND/boat. Variable cost is at 1,458.1±542.6 thousand VND/day. Turnover is at 2.14±0.62 million VND/day. Profit rate is at 0.35±0.21 times. Totally 42% fishermen stated that fishing yield decreasing by overfishing; and 40% by climate change. Totally 72.5% fishermen used to learn about climate change, but they have not good solutions to cope with them. They need support from government for better fishing operation and for better livelihood. However, trawling net with small mesh size of cod-end which may destroy coastal fishery resources should be controlled strickly.

This study was aimed to evaluate the growth and survival of bighead catfish  at fingerling stages from intraspecific crossbreeding of three broodstock sources including wild fish in Ca Mau (CM) and Long An (LA) and cultured fish in Can Tho (CT). Eight crosses  were nursed in 500-L tanks in two stages from day 2nd to day 30th (stage 1, 3 individuals/L) and from day 30th to day 75th (stage 2, 1 fish/3 L). Results in stage 1 showed that average length and weight of fish were not significantly different among treatments, ranging from 27.4 to 34.8 mm and 0.22 to 0.46 g, respectively. In stage 2, CMxCT had the highest length (62.0 mm) and weight (2.81 g), significantly different from the other crossbreeds (P 0.05).

Gac seed aril, a well-known natural food colorant, with high nutritional values. This study was conducted to evaluate the effects of pre-treatments on the antioxidant activity of gac (Momordica cochinchinesis Spreng) seed aril extract for further application research in fish oil preservation. Gac seed aril was pre-treated by soaking in ascorbic acid for 96 hours while untreated sample was considered as the control. The samples were then extracted in 96% ethanol to give crude extracts. Antioxidant activity was assessed through DPPH radical scavenging activity test and the total phenolic content in the extracts. The antioxidant capacity of aril extract supplemented in marine fish oil and salmon oil at 60°C were evaluated by determined peroxide value (PV) and Thiobarbituric acid reactive substances (TBARS). Results showed that using ascorbic acid in pre-treatment could preserve antioxidant properties and total phenolic content of gac aril extract. Extract pre-soaked in ascorbic acid indicated its potential application in preservation of marine fish oil and salmon oil.

The purpose of this study was to assess the susceptibility of whiteleg shrimp (Litopenaeus vannamei) to Vibrio parahaemolyticus, a causative agent of acute hepatopancreatic necrosis disease (AHPND), at different culture temperatures. Experimental shrimp (1.5 ± 0.13 g/shrimp) were randomly stocked with the density of 30 shrimp/tank (150L in volume) containing 15ppt seawater and constant aeration. Temperatures in experimental tanks (by a group of 12 tanks) were adjusted to 28°C, 30°C, 32°C and 34°C. Three days after being acclimated to different temperatures, shrimp from three tanks at each temperature were immersion challenged with V. parahaemolyticus. After 14 days post challenge, shrimp at 34°C were more susceptible to V. parahaemolyticus with significantly higher cumulative mortality (96.7 ± 2.9%) compared to thoese at lower temperature (P

U Minh National Parks, which comprises of U Minh Thuong (UMT, Kien Giang province) and U Minh Ha (UMH, Ca Mau province) with the typical Melaleuca forest ecosystem submerged in aluminum soil is a habitat for many freshwater fish species. This study was aimed to identify fish composition distributed in areas around UMT and UMH National Parks. After the sampling period (09/2017 to 08/2019), 54 fish species were found belonging to 40 genera, 23 families and 10 orders in UMT, and 31 fish species belong to 22 genera, 13 families and 6 orders in UMH. Ooders Cypriniformes and Perciformes show high numbers of species in both two areas. Nevertheless, fish in UMT area is more abundant and diverse. Particularly, there were 4 orders, 10 families and 20 genera only appearing in UMT such as Cyclocheilichthys apogon, Clupeichthys aesarnensis, Macrognathus circumcinctus, Parambassis wolffii,… Conversely, two fish species including Amblypharyngodon chulabhornae and Parambassis siamensis were found only in UMH. Differences in fish composition can be explained by levels of water exchange inside and outside of National Park and degrees of alum intrusion in water in these two study areas.

This study was aimed to evaluate effects of different feeding types on growth and survival rates of pompano (Trachinotus blochii) in a recirculating water system. An experiment was conducted at College of Aquaculture Fisheries, Can Tho University from November 2018 to December 2018. The experiment consisted of three different feed treatments, including (1) commercial feed, (2) commercial feed combined with trash fish and (3) trash fish. Pompano (3,96±0,54 g/fish) was stocked in rearing tanks of 500 L of salt water (20 ppt) at 30 fish/tank. Each treatment was repeated four times. After thirty days of rearing, the growth rate of fish fed commercial feed (0,24 gram/day and 0,77 %/day) and the commercial feed combined with trash fish (0,21 gram/day and 0,42 %/day) were significantly higher than that of fish fed trash fish (p

Disk abalone (Haliotis ovina) is one of gastropod species with high commercial values and important seafood products for consumption in domestic and international markets. Specimens were collected monthly from September 2017 to August 2018 at Nam Du Island, Kien Giang province at the south west coast of Vietnam to investigate the gonadal development and spawning season of this species. A total of 222 abalones were analysed and the results showed that the sexual ratio was approximately 1:1 with 52.3% male and 47.7% female. Gonad index of male abalone was highest in November (3.38) and December (3.70), whereas in female, this index was highest in January (3.83) and February (3.21). The highest diameter of eggs was also recorded in January (83.28 µm) and February (81.72 µm). The results of spawning proportions showed that abalone might spawn year-round with the high synchrony occurred in January to March and another in August. The results of this study could provide general information on the process of reproductive biology of disk abalone at the south west coast of Vietnam.

This study aimed to evaluate the effects of Alpinia officinarum and Punica granatum extracts as feed additives on immune system of red tilapia (Oreochromis sp.). Experiment was set up with 5 treatments in triplicate, including control, 1% and 2% of P. granatum extract; 1% and 2% of A. officinarum extract. The feeding experiment lasted for 4 weeks. Results revealed that the number of erythrocytes (RBC), leucocytes (WBC), lymphocytes, monocytes, neutrophils and thrombocyte of fish fed the additive diets was significantly higher compared to the control, in which the treatment of 2% A. officinarum showed the highest (p < 0.05). Phagocytic and lysozyme activities were significantly increased in additive feed groups compared with those of the control. However, the haematological, phagocytic and lysozyme activities of additive feed fed groups after 4-week feeding were did not significantly differ from those of 2-week feeding.

The study was conducted to determine the effect of green tea leaf extract on the quality of the whole black tiger shrimp during ice storage. Shrimp (25- 30 g) were soaked in green tea extract solution with concentrations of 0; 7.63 and 625 mg/mL at 4°C for 30 minutes. Shrimp after soaking were stored in ice and samples were collected on days 1, 4, 8 and 12. Analytical parameters included temperature, texture, total aerobic bacterial counts, sensory properties, water holding capacity, moisture, total volatile base nitrogen, peroxide value, thiobarbituric acid reactive substances and pH. Results showed that shrimp treated with green tea extract solutions (7.63 mg/mL and 625 mg/mL) showed significantly higher sensory properties, and significantly lower secondary oxidation products and total viable bacterial counts compared to control treatment during ice storage. Shrimp stored for 8 days under three types of treatments remained good quality based on the sensory properties and total aerobic bacterial counts.

A study on the fluctuation of fish stock of A. vachellii was conducted in the West estuarines of Ca Mau province from August 2017 to June 2019. Fish samples were collected twelve times with two-month intervals, by using trawl-net. Length frequency data were analyzed by using FiSAT II software. Results showed that this species was exploited year-round, but concentrated on the rainy season from June to October. The commonly exploited sizes of fish ranged from 3 cm to 5 cm. The analysis of length-frequency data of 6,922 individuals showed that the Von Bertalanffy growth parameters (VBGF) were L∞=7.35 cm and K=0.73/year. The total mortality (Z), natural mortality (M), and fishing mortality (F) of this species were 2.48 yr-1, 2.12 yr-1, 0.36 yr-1, respectively. The exploitation rate (E=0.15) was lower than that of the potential exploitation rate (Emax=0.421). The length at first capture was 3.36 cm with two recruitment peaks in May and October in this species population.

The study was carried out to compare the pathological characteristics of the Edwardsiella ictaluri bacterium causing bacillary necrosis disease in striped catfish (Pangasianodon hypophthalmus) and red tilapia (Oreochromis sp.).  Isolated bacteria which were isolated from striped catfish and red tilapia diseases were identified as Edwardsiella ictaluri based on morphological, physiological, biochemical characteristics, API 20E kit and PCR with specific primers for E. ictaluri. Samples of bacillary necrosis disease have atypical external pathological signs but there are many white spots on the internal organs. Typical histological changes at the location of white spots in liver, spleen and kidney of diseased fish included the formation of granular necrosis and granulomas. The results of pathogenicity experiments showed E. ictaluri strains which were isolated from diseased striped catfish were able to cause bacillary necrosis disease in both striped catfish and red tilapia when injected with lethal dose 50 (LD50). However, injection of E. ictaluri strains which were isolated from diseased red tilapia solely caused bacillary necrosis disease in red tilapia not striped catfish. The LD50 values of E. ictaluri in red tilapia and striped catfish (same size of 7.5 - 10g/fish) were approximately 4.7x103 CFU/mL and 3.6x105 CFU/mL, respectively.

This research was aimed to evaluate levels of genetic diversity and differences among populations of Malayan leaffish in the Mekong Delta. Fish samples were collected from three locations representing two types of habitats, including wetland conservation areas (Lang Sen-Long An and U Minh Ha-Ca Mau) and inland water bodies in Hậu Giang. Six inter-simple sequence repeats (ISSR) markers were used to amplify 95 samples. Results showed that 56 bands (5 to 12 bands per marker) were yielded with the polymorphic rate (P, %) of 86.9% and expected heterozygosity (He) of 0.250. Long An population (n=33) had the highest genetic diversity parameters (P = 98.2%; He=0.289), which were not significantly different (P>0.05) from those of the other two populations in Ca Mau (n=30; P=80.4%; He=0.239) and Hau Giang (n=32; P=80.4%; He=0.245). The three populations had high levels of genetic identity and a large number of migrant per generation (Nm=9.3). Analyses of Nei’s genetic distance and phylogenetic tree indicated Ca Mau and Hau Giang had a genetically closed relatonship, smaller than those between these two populations and Long An population.

The study was conducted to assess combined effects of red seaweed (Gracillaria tenuistipitata) densities and aeration regimes on nitrogen (N) and phosphorus (P) compound absorption of red seaweed in effluent from the intensive black tiger shrimp ponds. A two-factor experiment consisted of eight treatments, which was set up with four seaweed densities (0, 1, 2 and 3 kg/m3) in combination with two aeration regimes (aeration and non-aeration). Each treatment was randomly designed in triplicate tank for seven days. Results showed that the highest treatment efficiency of nitrogen (TAN, NO3- and TN) and phosphorus (PO43- và TP) compounds in wastewater was observed in the treatment of 3 kg/m3 combined with aeration, which can meet the standard of QCVN 02-19: 2014/BNNPTNT. Proximate composition of red seaweed after seven days of experiment such as moisture, lipid and fiber contents showed a minor change. Particularly, the protein content of red seaweed in all treatments was significantly higher as compared to the original material while carbohydrate levels were statistically lower than the initial samples.

Studying was performed through interviewing 40 fishermen. Results showed that boat power: 26.30±14.54 CV; gillnet length, height and mesh size are at 3,613.10±2,269.31 m, 3.59±1.86 m, and 2a=53.4±15.5 mm, respectively. Average labor 3.65±1.42 people/boat (51.42% from family); Average fishermen age: 40.08±11.13 years old; Fishing experience: 18.10±11.31 years; Educated rate: 75% for primary school. Ratio of operated boats: 60-87.5% per month; number of operated months: 9.3±3.11 months/year; fishing yield: 4.44±2.21 tons/year. Reasons for decreasing yield: overfishing (100%); climate change (47.5%); fishing gears (22.5%); polluted (20.0%). Total investment cost: 130.8±74.1 VND millions/boat. Depreciation rate: 3.2±2.3 VND millions/month. Variable cost: 1,014.8±392.9 VND thousands/day. Profit rate: 0.64±0.49 times. Having 45% fishermen used to hear about climate change; 62.5% fishermen showed some of climate change manifesting. 47.5% fishermen having temporary solutions.

Herbal plants are used to improve health, prevent and treat aquatic animal diseases, especially in marine shrimp farms in the Mekong Delta. However, detailed information on the use of herbal plants in shrimp farming in the Mekong delta is limited. This kind of information is important in the assessment of the characteristics, needs and potential use of herbal plants for the marine shrimp industry. The current study reports on a survey conducted in 2018 into the current use of herbal plants in shrimp farming. Ninety shrimp farmers in Ca Mau and Soc Trang provinces participated in the survey. Results showed: (i) herbal plants were used in both intensive shrimp farming in earthen ponds and super-intensive shrimp farming in plastic-lined ponds. The percentages of farmers using herbal plants in Ca Mau and Soc Trang were 58% and 51%, respectively; (ii) 18 herbal plant species were used in the shrimp farming process. (iii) the enhancement of shrimp immune system was the reason for application of herbal plants by most of shrimp farmers, followed by antibacterial activity of herbal plants; (iv) in Ca Mau, the group of farmers using herbs reported differences in the size of the harvested shrimp, costs and profits compared to those in the herb-nonuse group. It can be concluded that the use of herbal plants in marine shrimp farming in the Mekong Delta has demonstrated positive effects and has the potential to become widespread in a near future.

The aims of this study were to evaluate the effect of temperature on physiology and growth of striped catfish (Pangasianodon hypophthalmus) from fry to small fingerling stage. The study consisted of two experiments including (i) determination of temperature threshold; and (ii) effects of temperatures (24, 27, 30, 33 and 36°C) on physiological parameters, digestive enzyme activities and growth of fry reared in tanks for 60 days. The upper and lower temperature thresholds striped catfish fry were 35 and 21°C, respectively. Hematological parameters increased at 30°C treatment. The fish was stressed at the temperatures of 24°C and 36°C, which are indicated by the increase of glucose and cortisol levels and lower growth, i.e. 2.09±0.14 g and 2.47±0.16 g, respectively (p

Studying on species composition and distribution channel of fishing products from trawler and gill net activities were conducted from January to September, 2019 in Soc Trang province with the aim to provide information for sustainable development of these activities. Trawler fishermen (44 households) and gill net fishermen (43 households) were interviewed about technical and financial aspects. The catch of five gill nets and five trawlers were collected to determine the species composition, and five buying agents were interviewed on the trading activities of fishing products. The results showed that trawlers and gill nets could provide caught products whole year round. The yield and trash fish of gill nets and trawler were 14.1 tons/year, 7.8% and  17.7 tons/year, 45.2%, respectively. The harvested products of the trawlers were mainly sold to the buying agents (79.3%); then the buying agents sold  to the processing factories (73.4%). For the gill nets, the products were mainly sold (97%) to buying agents and buying agents, then sold to retailers (77%). The remaining products were for export (15%) and for drying fish production (5%). The annual profit of buying agents was 4.26 VND billion/ year with benefit ratio of 0.16 fold. Most of the buying agents encountered the greatest difficulties including declining in catches and unstable buying season which have affected the their business.

The study was conducted to investigate the effect of salinity on the density of Vibrio spp. in water and sediment in the upper part (Nhu Gia), middle part (My Thanh 1) and lower part (My Thanh 2) of My Thanh river. Samples were collected once a month from July 2017 to June 2018 at low and high tides. Bacterial density was determined by colony plate counting. Results showed that Vibrio density was highest in the sediment at the lower part (2.6 × 105 CFU/mL) and lowest at the upper part (5.5 × 102 CFU/mL). Total Vibrio spp. tended to increase with salinity. The density of Vibrio harveyi and V. parahaemolyticus in sediment in My Thanh 2 was the highest. When salinity was higher, the total density of Vibrio spp. and V. parahaemolyticus increased with a positive correlation. In water, V. harveyi density had a negative correlation with salinity. In sediment, V. harveyi density had a positive correlation with salinity.

The study investigated morphology of largescale tonguesole (Cynoglossus arel) in Kien Giang sea from September 2017 to August 2018. Samples after were collected and washed, put in ice box storage tanks and transferred to the laboratory at College of aquaculture & fisheries, Can Tho University. Results show that Cynoglossus arel is long, flat on both sides of the body. The eyes are small, located on one side of the head. Lateral line scales 56-70, and in the middle of the side line of the body 7-9. Cynoglossus arel is a benthic fish. The digestive tract of the fish consists of a small mouth with a hook-shaped shape, an asymmetrical jaw, no gill-comb, a small stomach (not distinguishable) and small intestine with a thin intestinal wall.

Research on using feed for giant freshwater prawn (Macrobrachium rosenbergii) nursing in rice fields was conducted at Thoi Binh district, Ca Mau province. There were two treatments of with (1) and without (2) supplementary feed. Post larvae were stocked at 3 ind./m2. Water quality parameters, the phytoplankton and zooplankton abundance in the field were examed twice a month. Results showed that water quality (temperature, pH, salinity, DO, alkalinity, N-NH4+ and N-NO2-), number of planktons, zoobenthos did not adversely affect the growth and development of giant freshwater prawn. After 2.5 months of rearing, the final mean weight of prawn in treatments 1 and 2 were 4.47 ± 0.05 g and 3.78 ± 0.13 g, respectively. The daily weight gain ranged 0.059 ± 0.059 g/day and 0.050 ± 0.046 g/day. The survival rate and yield of prawn in treatment 1 (56.4% and 7.56 ± 0.58 g/m2, respectively) were significantly higher (P

The aim of this study was to determine factors affecting the quality of black tiger shrimp (Penaeus monodon) floss. The study was conducted with four experiments: (i) the effect of glycerol and fish sauce proportion, (ii) the influence of stir-frying tiger shrimp floss condition, (iii) the effect of storage conditions on the quality of shrimp floss product. The results showed that the product achieved good sensory properties when shrimp floss was added with glycerol and fish sauce at the concentrations of 2% and 6%, respectively. Stir-frying as following to method 2 (stir-frying to moisture of 29,95%, stirring product and incubating for 1 hour before stir-frying to moisture 19,95% of shrimp floss product) could allow the appropriate water activity (0,547) and recovery rate of product (19,94%). The shrimp floss product vacuum-packed in polyamide (PA) plastic bags and stored at cool temperature (4±1⁰C) could be maintained a good quality up to 3 weeks, ensuring microbiological safety for the product.

The study was conducted to evaluate the effects of salinity on physiological parameters, digestive enzyme activities and growth performance of snakehead fish at fry to fingerling stages. Snakehead fish were acclimated and reared in tank condition at 5 salinity levels of 0, 3, 6, 9 and 12‰. After 90 days of rearing in different salinities, the number of red blood cells, white blood cells, hemoglobin, glucose, Na+, Cl- and osmolality were not significantly changed, however, hematocrit level decreased significantly at 9‰ treatment. The cortisol concentration was highest in 9‰ treatment. The activity of amylase, chymotrypsin and pepsin enzymes were not affected by salinity but the trypsin activity significantly decreased at 6‰ and 9‰ treatments. In treatments of 0 and 3‰, the fish growth was higher than the other treatments; the survival rate was highest at 3‰. The results suggested that the fry of snakehead can be reared at the salinity from 0 to 3‰.

The study was conducted to evaluate the effects of Punica granatum extract on growth performance and immune response of catfish (Pangasianodon hypophthalmus). The experiment was in the completely randomized design with three treatments including 0% (control); 1.5% and 3% supplemented P. granatum extract for 4 weeks. After four weeks, fish were infected with Edwardsiella ictaluri. The parameters including the erythrocytes, leukocytes, lymphocytes, monocytes, neutrophils, thrombocytes and lysozyme activity were examined in the week 2nd, 4th of experiment and day 3rd post challenge test. Results showed that supplemented P. granatum extract enhanced the growth performance of striped catfish. In addition, total leukocytes, monocytes, lymphocytes and lysozyme activity significantly increased in treatment of supplemented P. granatum extracts compare to the control (p

The study was carried out with bighead catfish (Clarias macrocephalus) reared in a recirculating aquaculture system (RAS) that consisting of 100-L culture tank, 30-L swirl separator, 60-L sump tank and 70-L moving bed biofilm reactor. Four different sizes (10 g, 30 g, 70 g and 100 g) of fish was stocked at density of 100 fish/tank then fed to ad libitum rate by floating pellets (41% crude protein) for 15 days. In the total of feed supply, retention in fish accounted by 25.4-32.7% in dry matter (DM) and 28.6-42.7%  in nitrogen (N); waste production by fecal loss made up 8.8-23.1% of DM and 14.7-40.0% of N; and non-fecal loss accounting for 12.8-15.3% of DM and 36.7-38.4% of N. The remaining was consumed by bacteria and lost by evaporation and seepage. Results also revealed that to produce 1 kg of fish, it was necessary to provide 780.6-1,033.7 g DM containing of 48.5-64.3 g N. Of which, nutrient accumulation in fish was 255.2-262.3 g DM and 20.0-21.1 g N; released in waste production of 525.4-771.5 g DM and 27.5-44.3 g N.

The objective of this research was to assess the diversity of zooplankton composition and using them as indicators in water quality monitoring on the Hau river. Zooplankton samples were collected at 19 sites on the Hau river starting from An Giang province to Can Tho city in March, 2019. The results revealed that total of 106 zooplankton species were found on Hau river, in which, Rotifera was the most abundant group with 39 species (accounting for 43%), followed by Protozoa, 28 species (28%), and others from 10-14 species (9-13%). Species composition and density of zooplankton in tributaries were higher than that in the main river. Significant positive correlations (P

The research aimed to assess the effect of salinity variation on composition of zooplankton. The study consisted of 8 triplicated treatments of salinities (0, 5, 10, 15, 20, 25, 30‰ and natural seawater. Salinity was gradually increased from 0 to 5‰ within 6 hours in 5, 10, 15, 20, 25 and 30‰ treatments and maintained for 1 week. Similarly, salinity in the treatments was increased continuously in the following weeks until the desired salinity was reached in every treatment. All experimental tanks had in bottom a mud layer of 10 cm. The experiment was randomly designed in 1.000 L composite tanks in outdoor condition. The results showed that a total of 84 zooplankton species were recorded during the experiment. Rotifera was the most abundant group with 35 species (42%), followed by Protozoa with 28 species (33%), others from 2-14 species (2-17%). Cladocera was not recorded any species at higher salinities of 5‰. Freshwater zooplankton species belonging to Protozoa, Rotifera and Copepoda gradually disappeared and replaced by the others when salinity increasing. There was significantly negative correlation (P

Study on the reproductive biology of largescale tonguesole (Cynoglossus arel) was conducted for one-year round from September 2017 to August 2018. Fishes were collected once a month in Kien Giang sea area, total of 780 fishes were collected during study period. The samples were washed with fresh water, then were refrigerated and transferred to the laboratory at College of aquaculture & fisheries, Can Tho university  to store in the freezer (-20oC) and conduct analysis. The study focused on reproductive biology such as sex ratio, ovarian development stages, gonadosomatic index, spawning season, fecundity. The results of research show that largescale tonguesole spawned mainly in April and October. The absolute fertility averages 11,938±1,523 eggs/female, the relative fertility averages about 112±15 eggs/g female with body weight 88.03-154.23 g/fish.

The study aimed to evaluate effects of different broodstock sources on reproductive traits and larval development of bighead catfish. Three broodstock sources including two wild populations (Ca Mau, CM and Long An, LA) and one cultured population (Can Tho, CT) were conditioning cultured for three months. When the fish got the maturation stage, six to nine pairs of breeders from each source were artificially produced in nine reciprocal crosses. CM females had the lowest relative fecundity (25,700 eggs/kg) with the highest egg diamter (1.77 mm), significantly different from those of LA and CT sources (57,000 to 60,800 eggs/kg and 1.68 mm, respectively). Fertilization rates (FR, 71.2±20.7%) and hatching rates (HR, 67.3±23.6%) were affected by females sources (P0.05). The highest FR and HR were found in CM female crosses. Yolk sac absorption lasted for 54 to 60 hrs. post hatch. Larval sizes at hatch and in five days differed among male and females sources and nine crosses (P0.05).

The research was conducted to investigate the effect of technological factors on glucosamine hydrochlorua quality extracted from black tiger shrimp (Penaeus monodon) shell through demineralization and deproteinzation process to obtain chitin. After that, the crude chitin was hydrolyzed by using HCl with various concentrations to produce glucosamine hydrochlorua. The results showed that demineralization by HCl 8% for 9 hours, the lowest mineral content was 0.89%. The protein content accounted for 6.43% by deproteinzation in NaOH 10% for 16 hours. The recovery yield of glucosamine hydrochlorua was highest (57.30%) when HCl concentration of 12 M was used to convert chitin to glucosamine hydrochlorua. The FTIR spectrum analysis revealed that glucosamine hydrochlorua product was similar to commercial products. The final product dried at 50 °C for 10 hours had moisture content, the highest recovery yield and solubility of 3.93%, 60.83%, 84.0%, respectively.

Research on the survival rate, growth, feed conversion ratio, nutrients (protein, lipid) utilization efficiency and retention of red tilapia (Oreochromis sp.) 7.06 g was conducted on two environmental cultured conditions: normal (28oC-0‰) and high temperature and salinity (34oC-12‰) with six diet treatments consisting three  levels of protein (25, 30 and 35%) and two levels of lipid (6 and 9%) corresponding to the energy level is 13.42, 15.76, 17.99, 12.90, 15.26, and 17.84  KJ/g; and the dietary energy ratios originated from protein/lipid 2.59, 3.08, 3.67, 1.71, 2.01 and 2.33, respectively over a 25-day period. The results showed that the high temperature and salinity (34oC-12‰) of cultured environment significantly increased the survival rate; growth; feed intake; and retention of nutrients (protein and lipid), but did not affect HSI (hepatopancreas volume) of red tilapia. The dietary ratio of energy originated from protein and lipids only influenced the retention of protein (NPU). The optimal dietary ratio of energy (protein: lipid) for red tilapia is 2.8 at normal cultured condition (28oC-0‰); 2.6 at high temperature and salinity (34oC-12‰) and this means red tilapia cultured in high temperature-salinity preferred energy from dietary lipid

This study was conducted to investigate drugs and chemicals use in snakehead (Channa striata) intensive cultured system. Interview data, including farming area, fish stocking density, disease outbreak, drugs and chemicals use during culture operation, were collected from 94 households in An Giang and Tra Vinh provinces. According to the feedback of farmers, diseases on snakehead included white spots in internal organs (82 – 88%), pale skin disease (40 – 71%) and epizootic ulcerative syndrome (60 - 75%). Most of the farmers were unknow about antibiotics susceptibility testing in treating fish diseases. The most frequently used antibiotics were florfenicol (21 - 76%), doxycycline (17 - 68%), combination of florfenicol and doxycycline (17 - 40%), combination of sulphonamides and trimethoprim (26 - 33%), amoxicillin (29 - 30%). Banned chemicals (enrofloxacin and malachite green), which do not belong to the approved list by the Ministry of Agriculture & Rural Development, were found during the survey. Our suggestion is that it is necessary to train fish farmers in disease management and drugs and chemicals use.

The technical assessment of Trachinotus blochii in Ninh Thuan and Khanh Hoa from from September to December 2018, this is the basis for proposing solutions to improve the technical efficiency of cage fish farming. Subject directly interviewed 42 farmers prepared form with the contents of the technical aspect, the economic efficiency of animal model. With Trachinotus blochii farming model in Ninh Thuan and Khanh Hoa: average volume of 50.4-60.2 m3 cage with stocking density is 4.5-12.5 /m3; the average size of 5.2-5.4 cm breed; culture period ranged 9-11 months, the size fish harvested from 0.99-1.03 kg/head; survival rate of 76.6-85.7% average fish. The average FCR of 8.3-18.8; average yield of 353.1-1019.4 kg/m3; The average profit of 103.5-152.8 million fish/100m3. The rate of return 41,6-56,4. Overall, farming Trachinotus blochii in cages and in the Ninh Thuan and Khanh Hoa bring high efficiency but not stable. Need planned reorganization farming areas and good looking fish increase and reach a high survival rate.

Studying on the status of fishing and consuming abalone (Haliotis) in Nam Du archipelago was conducted from January to April 2019 by interviews of 40 fishermen. The results showed that fishing season of abalone are all year a round, but the main season is from February to May. Sharp hook was main gear used to exploit abalone. The yield in the rainy season (0.5 kg/fishing trip) was lower than in the dry season (3.0 kg/fishing trip). The income of fishermen depended highly on fishing, in which abalone fishing was 12.5%. The profit from abalone fishing was 1.71 million VND/fishing trip. The erratic change of the weather greatly affected abalone fishing in Nam Du archipelago.

The study aimed to assess water quality in the rivers around the upper parts of My Thanh river and My Thanh, Hau estuary with 10 sites to provide a basic for the management of water resources in areas. Samples were collected for 6 months. The results showed that temperature and pH were in a range of national standard surface water quality. Salinity was highly variable during the sampling duration, reaching the highest value of 21‰ in the estuarine. Alkalinity, DO, BOD5, COD, TAN and NO3- suitable for aquaculture activities. Concentrations of TSS, NO2-, PO43-, density of microorganisms were quite high. Water quality in the upper parts and tributaries of My Thanh River is influenced strongly by domestic wastewater, agriculture and aquaculture activities and high fluctuation if compared to those waters in the estuarine and coastal areas.

The current study was investigated to evaluate the effect of asthma plant (Euphorbia hirta L.) extract on the quality of snakehead (Channa striata) fillets during iced storage. Snakehead fillets were soaked in asthma plant extract solutions at concentration of 14.08 µg/mL (concentration of 50% DPPH exhibition) and 625 µg/mL (minimum inhibitory concentration, MIC) and in cold tap water as a control, for 30 minutes. Fish fillets were packed and stored in ice with fish and ice ratio of 1:1. Fish quality were evaluated after 1, 4, 8 and 12 days of storage through total aerobic bacteria count, chemical and physical parameters (structure, water holding capacity, total volatile base nitrogen, peroxide value, Thiobarbituric acid reactive substances, temperature and pH) and sensory analysis,. Results showed that snakehead fillet treated with asthma plant (14.08 µg/mL and 625 µg/mL) extract solutions showed significantly higher sensory property compared to control treatment during storage. Based on the sensory properties and total aerobic bacteria count, snakehead fillets treated with asthma plant can be used up to 8 days whilst less than 8 days for control treatment.

Technical efficiency of the white leg shrimp farming at household scale in the Mekong Delta in this study was analyzed from the Cobb-Douglas stochastic production frontier function. The data was collected from  two hundred and four white leg shrimp farms in Soc Trang và Ben Tre provinces. The results showed that the average technical efficiency level was 69.0%, of which 31.4% of households reached technical efficiency over 80%. The average yield loss due to technical inefficiency was 2.2 tonnes/ha/crop. The main reason was unreasonable usage of input of famers. There were 94.6% of the inefficiencies caused by the inputs that farmers could control such as stocking density, labor days and cost of veterinary. Educational level, production financial capital and production cycle were found to have effects on the technical efficiency.

The research on effects of Tegalase enzyme concentration on the hydrolysis process as well as the influences of the heating time, drying conditions on the quality of fish protein and calcium powder from Tra Catfish bone was investigated. The results showed that hydrolysed sample at 50°C for 24 hours with the Tegalase enzyme concentration of 0.1% was obtained the formation of peptide bond was the highest (2,935 peptit bonds) and amino acid was 14.8% in fish protein solution. Furthermore, bone which collected after hydrolysis also got the highest mineral content (37.4%) and the lowest protein content (17.5%). The protein solution was heated at 95-100°C within six minutes for the highest axit amin content (17.7%). After which, it was dried at 60 °C for one day to achieve moisture content, recovery yield and protein concentration (4.64, 5.48 and 68.9%, respectively). And fish bone was also treated at the same drying temperature for four hours to get 10.8% moisture and calcium accounts for 22.9%.