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Assessment of Hatching, Survival and Growth Rate of Two New Common Carp Strains (Tata and Szarvas P3) Introduced from Hungary to Vietnam

Nguyen Hai Son, Vo Van Binh, Le Ngoc Khanh, Le Khanh Thuy Linh, Mai Van Tai, Nguyen Thi La

Received: 20-08-2021 / Accepted: 10-01-2022
The objective of the study was to evaluate the hatching rate, the survival rate of fry, fingerling, juvenile and the growth rate for breeding. Experiment on hatching, nursering and rearing of two introduced common carp strains (Tata and Szavas P3) from Hungary to Vietnam was carried out from July 2019 to December 2020 at the National Freshwater Broodstock Center. The results showed that the hatching time was 61.8 and 62.2 hours for Tata and Szavas strain, respectively; the figure of the hatching rate was 91.5% and 93.3%, and the deformity rate was 1.2% and 1.3%, respectively. The survival rate of Tata fingerling was 62.5% and of Szavas P3 was 67.5%. The survival rate of juvenile Tata carp was 48.7%, Szarvas P3 carp was 53.3%. The absolute growth in length and weight of Tata carp was 6.8mm/day and 0.51 gam/day, Szarvas P3 was 6.5 mm/day and 0.49 gam/day. After 12 months of culture, the average weight and length of Tata carp was 1670.5 ± 10.2 g/fish and 50.2 ± 7.1 cm/fish, Szavas P3 carp was 1565.5 ± 10.2 g/fish and 49.3 ± 7.7 cm/fish, the feed conversion ratio values was 2.0 for Tata and 1.9 for Szavas P3 carp. The results of hatching, nursering and rearing showed that Tata carp and Szavas P3 carp can be used as genetic material for selection breeding .
Effects of Stocking Densities, Types of Feed on the Growth and Survival Rateof Yellowcheck (Elopichthys BambusaRichardson, 1844) from fry to Fingerling Stage

Nguyen Hai Son, Vo Van Binh, Nguyen Huu Quan, Dang Thi Lua

Received: 27-08-2021 / Accepted: 01-03-2022
The experiment on nursing the Yellowcheck (Elopichthys bambusa) from larvae to fingerling at different stocking densities and feeds was carried out from July to December 2020 at the National Freshwater Broodstock Center to determine the appropriate stocking densities and suitable feeds used in the nursering and rearing of larvae and fingerlings Yellowcheck. The results showed that the larvae reared at a density of 4-5 fish/liter gave a higher survival rate and growth rate than those nursed at a density of 6-7 fish/liter. The survival rate and growth rate of fish stocked at a density of 0.6 fish/liter were higher than those stocked at a density of 1 fish/liter and 1.2 fish/liter. Using 100% zooplankton and 60% zooplankton feed combined with 40% small worms for rearing fry gave the survival rate and growth rate higher than using feed consisting of 60% zooplankton with 40% fishmeal. In the period of rearing fingerlings, using larvae silver carp, small worms, and 30% small worms combined with 70% larvae silver carp, had a higher survival rate and growth rate than using feed containing 70% of larvae silver carp and 30% of larvae shrimp (45% protein).
Study on Maturation Broodstock Culture and Artificial Reproduction of Yellowcheek (Elopichthys bambusaRichardson, 1844)

Nguyen Hai Son, Vo Van Binh, Dang Thi Lua

Received: 25-03-2021 / Accepted: 22-06-2021
The study on maturation broodstock culture and artificial reproduction of yellowcheek (Elopichthys bambusaRichardson, 1844) was conducted from 12/2019 - 8/2020 at the National Freshwater Broodstocks Center. The aim of this study was to identify suitable foods for culturing maturation broodstocks, optimum hormone dose and appropriate incubation equipment for producing yellowcheek seeds. The results indicated that the use of chopped silver carp as food for culturing yellowcheek broodstock in the pond provided the higher maturation rate of broodstocks than using a food formulation consisting of 50% silver carp + 50% pellet feed and using 100% mixed pellet fish with 40% protein. Hormone dose of 60µg LRH-A + 10mg DOM/kg female gave the highest ovulation rate with the effect of hormones from 5-6 hours at 27-31C. Using Weiss incubators (Cycle tank) for incubating eggs showed a higher hatching rate (84.4%) and survival rate after 13 days (56.7%) in comparison with trays (68.7% hatching rate, survival rate 45.7%).
EFFICACY OF PRAZIQUANTEL AGAINST EXTERNAL PARASITES INFECTING FRESHWATER FISH

Truong Dinh Hoai, Kim Van Van

Received: 04-03-2014 / Accepted: 13-08-2014
Praziquantel has been used to control external parasites on marine fish but there is little data about its effect on treating external parasites infecting freshwater fish. This study examined whether praziquantel was able to control external parasites on freshwater fish in Vietnam. Four external parasites, monogenean trematode (Dactylogyrus sp.), parasitic Crustacea (Lenear sp.) and two ciliated Protozoa (Trichodina sp. and Epistylis sp.) naturally infecting Grass carp (Ctenopharyngodon idella), Common carp (Cyprinus carpio) and Tilapia (Oreochromis niloticus), respectively, were experimentally treated. Infected fish were exposed to praziquantel in baths for periods of 1, 3, 24, 48 and 72 hrs at each of five different concentrations 2.5, 5, 7.5 and 10 mg/l with a control (0 mg/l) treatment. Doses of 7.5-10 mg/l praziquantel administered for 1-3 h for fish infected with two ciliated Protozoa and 24-72h for the other two parasites were effective in eliminating all parasites without killing the fish. Thus, praziquantel of doses at 7.5-10 mg/l immersed within 72h duration is an appropriate therapy for simultaneous treatment of a number of external parasites of freshwater fish. The results have important implications in the management of fish health in current aquaculture systems.
Microalgal Composition in Fish Ponds at the Vietnam National University of Agriculture

Doan Thanh Loan, Nguyen Khanh Linh, Hoang Thi Tam, Le Thi Hoang Hang, Nguyen Cong Thiet, Hoang Dang Dung, Pham Thi Lam Hong

Received: 01-03-2023 / Accepted: 07-03-2024
This study was carried out to build a database of microalgae in fish ponds at the Fisheries Faculty of the Vietnam National University of Agriculture. Water samples were collected to examine the frequency of occurrence and microalgal composition in five aquaculture ponds. A total of 30 microalgal samples (15 from winter and 15 from summer) were analyzed in this study. The results showed that there were 136 microalgae species from 8 classes, 11 orders, 26 families, 49 genera, and 6 phyla (Euglenophyta, Chlorophyta, Cyanobacteriophyta, Bacillariophyta, Pyrophyta, and Xanthophyta). The number of microalgal species was abundant in summer. There were 27 microalgae species that could be used as live food for zooplankton. The occurrence of 12 microalgae species is a bioindicator of organic compound enrichment in water. There were three microalgae species that could cause harmful algal “blooms”.
Microalgal Composition in Fish Ponds at the Vietnam National University of Agriculture

Doan Thanh Loan, Nguyen Khanh Linh, Hoang Thi Tam, Le Thi Hoang Hang, Nguyen Cong Thiet, Hoang Dang Dung, Pham Thi Lam Hong

Received: 01-03-2023 / Accepted: 07-03-2024
This study was carried out to build a database of microalgae in fish ponds at the Fisheries Faculty of the Vietnam National University of Agriculture. Water samples were collected to examine the frequency of occurrence and microalgal composition in five aquaculture ponds. A total of 30 microalgal samples (15 from winter and 15 from summer) were analyzed in this study. The results showed that there were 136 microalgae species from 8 classes, 11 orders, 26 families, 49 genera, and 6 phyla (Euglenophyta, Chlorophyta, Cyanobacteriophyta, Bacillariophyta, Pyrophyta, and Xanthophyta). The number of microalgal species was abundant in summer. There were 27 microalgae species that could be used as live food for zooplankton. The occurrence of 12 microalgae species is a bioindicator of organic compound enrichment in water. There were three microalgae species that could cause harmful algal “blooms”.
Survival and Growth Ratesof White-Leg Shrimp Litopenaeus Vannamei(Boone, 1931) Reared in Freshwater and Saline Brackishwater

Le Viet Dung

Received: 24-09-2018 / Accepted: 07-11-2018
This study compared the growth and survivalratesofwhite-leg shrimp (L. vannamei) which were reared in freshwater at 0 ppt and in saline brackishwater at 30 ppt. PL34 shrimps were reared at the density of 1 individiual/L (200shrimp/m2) for 21 days. Shrimps of each treatment were reared in three 40 L tanks. Results showed that there was no significant difference in survival and growthratesofthe white-leg shrimpshrimpbetween the two treatments during the whole culture period. The survival rates of shrimp reared at 0 ppt and 30 ppt were 62.5 ± 10.9% and 69.17 ± 7.64%, respectively. The weight gain of shrimp reached113.33± 15.28% for shrimp at 0 ppt and 106,67± 11,55% for those at 30 ppt. The specific growth rate of shrimp at 0 ppt and 30 ppt was 3.78 ± 0.36% and 3.63 ± 0.28%, respectively.In conclusion, white-leg shrimp could be reared in freshwater 0 ppt.
Effect of Ecological Zones of Fresh and Brackish Water on Rice Growth and Soil Chemical Characteristics in Rice-Shrimp System in Bac Lieu Province

Le Van Dang, Ngo Ngoc Hung

Received: 18-04-2018 / Accepted: 12-07-2018
The objectives of the study were to evaluate i) effect of ecological zones of fresh and brackish water on rice-shrimp cultivation systems, (ii) chemical characteristics of soil and water of the agro-ecological zones, and (iii) the efficiency of liming on rice growth and yield. Field experiments were conducted during August to December 2013 in Phuoc Long and Hong Dan, Bac Lieu province. Results showed that, after shrimp harvest, Phuoc Long planted rice crop in August when soil salt concentration was high (ECe: 8.0 mS/cm; ESP: 13.8%). Exchange cations in the soil decreased in the descending order: Mg2+>Na+>Ca2+>K+, corresponding to 8.0>3.0>1.5>1.0 meq/100 g, respectively. Due to salt accumulation in the soil in brackish water zone, ECe and ESP were at high levels during December (5,6 mS/cm and 7,8%, respectively), unfavourable for growth and yield of rice in comparison with fresh water zone at Hong Dan. Lime application to the salt-affected soil in Phuoc Long reduced salt damage to rice in terms of panicle number per square meter, filled grain rate, and higher grain yield (by 0.6 t ha-1) as compared to without liming. However, lime application to rice soil in fresh water zone at Hong Dan did not significantly increase the grain yield.
Study on Biological Characteristics of Onychostoma laticepsGunther, 1896

Vo Van Binh, Nguyen Hai Son, Nguyen Quang Huy

Received: 13-05-2019 / Accepted: 17-07-2019
In order to maintain, protect and develop the gene source of Onychostoma laticeps, the study of biological characteristics of O. laticepswas carried out from January 2018 to December 2018 on 300 samples of O. laticepscollected in the Giang River, Mon Son commune, Con Cuong district, Nghe An province. Results showed that all collected fish samples were in the age of ranging from 1+-3+, corresponding to the weight of 22.5-98.8 g/fish. The O. laticepsis an omnivorous species (Li/Lo was 3.08 ± 0.57). The food composition in the fish intestines was diverse, including more than 28 species, representing for 5 different animal and plant sectors, of which the algae sector was dominated (65%) compared to other sectors. There were no much differences between the Fulton fat coefficient and Clark fat coefficient, this was reflected correctly the level of the nutrient that was accumulated in fish. In nature, O. laticepsstarted breeding in early February, the average absolute fertility was 3,113 eggs, the average relative fertility was 231 eggs/g of the female. The gonosomatic index (GSI) was high during the period from February to June (Male fish ranged from 1.81 to 2.12%; Females fish from 4.62-9.80%) and reached the highest value in March (Male fish: 2.64%; Female fish: 9.80%).
The Exploitation Status of Yellowcheek (Elopichthys bambusaRichardson, 1844) Resources inthe Northern and Northern Central Provinces of Vietnam

Vo Van Binh, Nguyen Hai Son

Received: 26-08-2019 / Accepted: 14-10-2019
An evaluation on the exploitation status of Yellowcheek (Elopichthys bambusaRicharson, 1844)was conducted from January to June 2019 in the Northern and Northern Central provinces of Vietnam including Nghe An, Hai Duong, Hoa Binh, Son La, Yen Bai and Tuyen Quang provinces. The data on fishing gear, season and catch area, size of Yellowcheek, Yellowcheekproduction andthe ratio of Yellowcheek production per totalcatchesproductionare collected through, through direct interviews of 120 fishermen catching fish in rivers and reservoirs. The results showed that there were 5 fishing gears mainly used to exploit natural fish in the Northern and Northern central provinces, of which the three-layer gill net and lighting lift net were ofhighest rate of exploitation Yellowcheek. The peakfishing season of Yellowcheekwas from May to September in the surveyed provinces with the size of Yellowcheekvaried in the range of 100-5,000 g/fish depending on the type of fishing gear used and the location of exploitation. Yellowcheekwere exploited mainly in rivers and reservoirs, with an average fish production ranged from 8-20 kg/household/year. The natural resources of Yellowcheekaregradualy reducing due to the construction of hydropower dams and the use of nets with the small mesh size to exploit fish. Currently, catching Yellowcheekhas not been profitable for fishermen in the investigated areas.
Methods of Spawning Induction In Gastropoda -A Review

Le Van Binh, Ngo Thi Thu Thao

Received: 13-12-2021 / Accepted: 27-05-2022
The goal of this article was to summarize some of the mechanisms of spawning induction in gastropoda in the marine and freshwater environment. Nutritional and environmental factors (lighting, temperature, and the tidal cycle-for marine species) affected the changes of the endocrine system in gastropoda. The changes in environmental conditions also affected the change of reproductive structure. Illumination cycle, temperature, change of water source, and hydrogen-peroxide solution (H2O2) affected the central nervous system, stimulating the egg-laying process of most gastropoda. For marine gastropods, using H2O2solution and ultraviolet or heat shock all gave good spawning efficiency. However, other methods such as changing the water depth or combined with rain spraying, pituitary glandinjections, and tentacle cutting were more effective in spawning induction for freshwater gastropoda.
Acute Toxicity Testing of PyrethroidPesticide to Freshwater Snail (Angulyagrapolyzonata)

Nguyen Thi Thu Ha, Hoang Thuy Linh, Dinh Tien Dung, Trinh Quang Huy

Received: 25-01-2016 / Accepted: 06-06-2016
Pyrethroid pesticide toxicity testing onfreshwater snail (Angulyagra polyzonata)wasdone in laboratory scale by artificial exposure to Cypermethrin and Deltamethrin for96 hours period. The results showedthat Angulyagra polyzonatawas more sensitive toDeltamethrin than Cypermethrin.The recovery of freshwater snails was descending whenexposed to pyrethroids for 48 hours and then released into water within 48 hours. Bioaccumulation fator (BCF) with Cypermethrin was0.88and26.29 with exposure time of one day and one month, respectively.
Study on using Cellulase in the Processing of Beverage from Medical Mushrooms

Nguyen Thi Bich Hang, Nguyen Doan Nhat Quynh, Ho Thi Trang, Doan Chi Cuong, Bui Duc Thang, Tran Dinh Chi

Received: 18-08-2023 / Accepted: 12-04-2024
Cellulase was applied to improve the extraction efficiency from medicinal mushroom extracts of Ganoderma lucidumand Trametes versicolor. In addition, the study proposed the process of producing beverages from those medicinal mushrooms and chrysanthemum (Chrysanthemum indicum)flowers. The findings show that, for extracting from Yunzhi’s extract, using 3% cellulasefor 15 minutes attemperature of 70C gained the highest extraction efficiency. Meanwhile, the extraction efficiency from Lingzhi’s extract was highest with 4% cellulasein 25 minutes attemperature of 70C. Mushroom beverage with a mixture of 25% Lingzhi, 50% Yunzhi, 20% Chrysanthemum flowers, and 5% sweet grass (Stevia rebaudiana) had the highest sensory evaluation according to the TCVN3215-79. The processed product meets quality standards on food hygiene and safety according to QCVN 8-2/2011-BYT for permissible limits of heavy metals and Decision 46/2007/QD-BYT for biological and chemical contamination in food.
Polyculture of Whiteleg Shrimp (Litopenaeus vannamei) and Red Tilapia (Oreochromissp.) -A Response to Climate Change inGiao Thuy District, Nam Dinh Province

Kim Van Van, Ngo The An

Received: 05-02-2017 / Accepted: 09-03-2017
This study aimedat examining the model of integrated culture of whiteleg shrimp with red tilapia in the context of climate change (CC), an expectation for a good model for the local farmers to deal with climate change. The experiment was carried out in six ponds, ranging from 2000 to 2500 m2, in 2015 and 2016, in Giao Phong commune, Giao Thuy district, Nam Dinh province. The trials consistedof 6 models designed in six ponds: two integrated farms in freshwater, and four monoculture shrimp farms for control, two in brackish water and two in freshwater. In the integrated culture models, red tilapia was added at a density of 2 fish per m2to a pond stocking 100 white shrimp per m2; the shrimp were stocked twice but red tilapia was stocked only once per year. In the monoculture models, whitelegshrimp was stocked at the same time and the same density as those in the integrated models. Comparingto the monoculture of shrimp in both brackish and fresh water, the polyculture of shrimp with red tilapia where whitelegshrimp was acclimatized to fresh water resulted in lower disease incidence, reduced the cost of drugs and chemicals by about 30%, and gained more than doubled the economic benefits. Farmers and the local authorities in the district highly appreciated the results of the integrated culture model. This model can be considered as a strategy to increase the adaptive capacity of aquatic production in the study area.
In vitropropagation of Taiwanese Sweet Mulberry

Nguyen Thi Ly Anh, Nguyen Thi Thiet, Tran Thi Luyen, Dang Thi Nhan, Nguyen Thi Han

Received: 26-07-2018 / Accepted: 03-12-2018
In vitropropagation of Taiwanese sweet mulberry was carried out to determine technical parametersinthe production of high quality planting materialsfor expanding cultivated area of the newly introducedfruit tree. One-month-old shoots of two-year-old Taiwanese sweet mulberry plantswere used as initial materialsfor in vitroculture. Results showed that BA at the concentration of 3mg/l in MS medium was suitable for stimulating in vitroshoots from stem nodes with highrate(83.33%). BA at 3 mg/l in combination with0.5 mg/l IBA and 10% coconut water gave the best shoot multiplication rate (2.93 shoots/explant) and the highest shoot quality after 4 weeks of culture. The highest rooting percentage at 96.67% of shoots was observed after 4 weeks onMS medium containing 0.5 mg/l IBA. The plantlets were successfully acclimated in sandy substrate with a survival rate of 80%. The liquid fertilizer “Buffalo Head 502” foliar spary 1 time/weekyielded good quality plantlets suitable for transplanting into pots.This in vitropropagation process is highly effective and easy to apply at production scale.
Epidemiology of Zoonotic Metacercaria in Fingerlings of Common carp (Cyprinus carpioLinnaeus, 1758) in Aquaculture Systems

Kim Van Van, Nguyen Van Tho

Received: 28-09-2012 / Accepted: 25-10-2012
Fingerling fish quality in aquaculture was concerned by the Fisheries Sector, specifically the Common carp, a traditional species raised in fresh water and more likely infected with zoonotic metacercaria. To investigate the epidemiological situation 1536 fingerling samples of common carp at size of 10.55 ± 1.51 g/fish from 54 waterbodies (ponds, canals, rivers, rice-fields) in 6 aquaculture systems (integrated fish-pig; fish-duck, rice-fish, biogas slurry, intensive culture and natural systems) was collected to test metacercaria by tissue digestion method. The result showed that the averaged prevalence was 23.89% and the intensity was 6.9 metacercaria/fish. High intensity occurred in natural and integrated systems, but low prevalence & intensity were found in biogas slurry and intensive culture systems. Three metacercaria species of small intestine flukes (Centrocestus formosanus, Haplorchis pumilio, H.taichui) and one metacercaria species of liver fluke (Clonorchis sinensis) were found in fingerlings of Common carp. Metacercaria of C. formosanus caused opened gill disease in fry and fingerling fish. Two metacercaria species of C. formosanus and H. pumilio were found with high prevalence and intensity (19.47-19.53%; 3.82-3.93 metacercaria/fish).
Gross and Microscopic Morphology of Salt Glands in Sea Duck 15 Dai Xuyen

Vuong Lan Anh, Nguyen Van Duy, Hoang Van Tieu, Nguyen Thi Minh Phuong, Nguyen Ba Tiep

Received: 11-06-2018 / Accepted: 11-03-2019
Gross and histological structures of the salt glands of the sea duck 15 (VB15) and the F1(VB15 x mallards) ducklingswere investigated in this study. The ducks hadbilateral crescent salt glands under the skin in the supraorbital depression of the frontal bone. The measurements of the gland length, width and weight showed that the gland development wasfaster from post-hatching to 6 weeks of age. There were no differences of the three values among three duck groups raised in fresh water. The salt glandsof VB15 raised in sea water had higher weight than that of the counterparts in fresh water. The glands of VB15 consistedof concentric polygonal lobes arranged in rows and separated by interlobular connective tissuesthat contain vasculature system. Each lobe hadbranched striated secretory tubules lining with single layer of cuboidal cells. Connective tissue was underneath the cuboidal cellepithelia. Thebranchedductsopenedinto the central canal that drain in a main duct leads to the anterior of the nasal cavity. This is the first study on salt glands of Vietnam marine animals, especially of VB15breedand can be considered as the basisfor further studies on age-dependent functions of the salt glands and theoptimal age of VB15 for shifting from fresh water to salty water as well as appropriate salinity for VB15.
Experimental Study on all-maleGiant Freshwater Prawn (Macrobranchium rosenbergiiDe man, 1879) Two-phase Culturein Hai Phong

Dang Thi Thanh, Nguyen Trung, Nguyen Thi Tai

Received: 12-10-2021 / Accepted: 05-07-2022
This study was conducted with the aim of providing a farming procedure with appropriate technical criteria applicable to Hai Phong and Northern provinces. Stocking density in phase 1 was 150 juveniles/m2for the period of 50 days. Phase 2 was started with two different stocking densities: 15 prawns/m2and 20 prawns/m2, two replica for each for the same culture time of 134 days. The results show that the water quality in cultured system including water temperature, water pH, transparency, dissolved oxygen, NH3, NO2and H2S, aerobic total bacteria, Aeromonas, Pseudomonas, phytoplankton was in the acceptable limit for the growth of giant freshwater prawn. The survival rate of phases 1 reached 80% after 50 days. In phases 2 after 134 days, the survival rate and harvested size of prawns for the density of 15 and 20 prawns/m2 were 71% and 80.93 g/prawns; 68.5% and 76.96 g/prawns, respectively. Culture of all-male giant freshwater shrimp in two-phase with stocking density of 15-20 prawns/m2obtained high efficiency and could be applied to production.
Experimental Study on all-maleGiant Freshwater Prawn (Macrobranchium rosenbergiiDe man, 1879) Two-phase Culturein Hai Phong

Dang Thi Thanh, Nguyen Trung, Nguyen Thi Tai

Received: 12-10-2021 / Accepted: 05-07-2022
This study was conducted with the aim of providing a farming procedure with appropriate technical criteria applicable to Hai Phong and Northern provinces. Stocking density in phase 1 was 150 juveniles/m2for the period of 50 days. Phase 2 was started with two different stocking densities: 15 prawns/m2and 20 prawns/m2, two replica for each for the same culture time of 134 days. The results show that the water quality in cultured system including water temperature, water pH, transparency, dissolved oxygen, NH3, NO2and H2S, aerobic total bacteria, Aeromonas, Pseudomonas, phytoplankton was in the acceptable limit for the growth of giant freshwater prawn. The survival rate of phases 1 reached 80% after 50 days. In phases 2 after 134 days, the survival rate and harvested size of prawns for the density of 15 and 20 prawns/m2 were 71% and 80.93 g/prawns; 68.5% and 76.96 g/prawns, respectively. Culture of all-male giant freshwater shrimp in two-phase with stocking density of 15-20 prawns/m2obtained high efficiency and could be applied to production.
Simulation ofChanges inAgricultural Land use in the Coastal Area of Nam Dinh Province using the CLUMondo Model

Nguyen Thi Phuong Hoa, Ngo The An, Le Thi Giang

Received: 04-06-2021 / Accepted: 06-07-2021
This study applied the CLUMondo model to predict agricultural land-use changes to 2030 in the coastal area of Nam Dinh province. The predictions weredonebased on the correlations between the probability of changesrelated to each land use typeand its location suitability factors. Model outputs were validated by ROC statistic and Kappa coefficient.Results showedthatchanges inagricultural land use in 2030followed scenario 1 (baseline) with a decrease in rice areabut increase in the aquaculture area. The trend was similar in scenario 2 (as the land use planning) but the rice area was more decreased. In addition, in both scenarios, there was an increase in annual and perennial crops. Under the assumption of scenario 2, freshwater aquaculture tendedto continue expanding to paddies, while a portion of brackish water aquaculture wasconverted to forest land. Therefore, when implementing land use planning, it is necessary to prepare solutions for trading-off between staple food and aquaculture to ensure food security and sustainable development for local communities.
Use of Rotifer as Feed for Striped Catfish (Pangasianodon hypophthalmus) Fry

Huynh Thanh Toi, Huynh Thi Ngoc Hien, Nguyen Thi Hong Van

Received: 28-02-2020 / Accepted: 09-12-2020
The objective of this study was to assess the growth rate of some rotifer species and possibility to use them as live food for nursing of striped catfish (Pangasianodon hypophthalmus) fry. Three species of freshwater rotifers including Brachionus angularis, B. palaand B. calycifloruswas mass-reared and compared to brackish species B. plicatiscurrently used as live food for striped catfish fry in the Mekong delta. Then, these four rotifer species were used as feed for striped catfish fries within the first three days, followed by Moina used until the end of the experiment. The population of B. palaand B. calyciflorusattained its maximum density (increased 03 times) for day 03 and 04, respectively. Meanwhile, B. angularisandB. plicatilisreached its maximum density (increased 06 times) for day 07 and 09, respectively. The results on fish study showed that the highest survival was obtained (24.1%) in B. angularisfed fish, whereas the lowest survival was obtained in B. calyciflorusfed fish. The weight of B. angularis fed fish was significantly higher than B. calyciflorusfed fish, but the difference was not significant compared to B. plicatilisor B. palafed fish. The results of this study indicated that B. angularisis the optimal live food for striped catfish fry.
State Management in Development of Freshwater Aquaculture in Hai Phong City

Nguyen Huu Xuan, Nguyen Thi Minh Hien

Received: 25-09-2019 / Accepted: 11-11-2019
With the aim of evaluating the role of state management in freshwater aquaculture development in Hai Phong city, 136 aquaculture farms and 28 managers involving in freshwater aquaculture in Hai Phong were conducted. Statistical disaggregation, descriptive statistics and comparison were applied to analyze data and information. The results showed that besides some activities such as public service and production process management have been rather well-performed, other activities such as planning, management of input supply services and product markets were still faced with many shortcomings. In the coming years to develop freshwater aquaculture in Hai Phong, it is necessary to focus more on enhancing the role and capacity for local authorities at all levels.
Salinity Tolerance of Black Carp (Mylopharyngodon piceus)at The Fingerling Stage

Kim Van Van, Doan Thi Nhinh, Trinh Thi Trang

Received: 18-08-2015 / Accepted: 22-01-2016
To test the culturability in brackish water the experiment was carried out to evaluate the salinity tolerance of Black carp (Mylopharyngodonpiceus) at the fingerling stage. Fish at size of 45 ± 0,3 gram/individual were stocked in several 120L-buckets with stocking density of 15 fish/bucket. The experiment included in 2 trials: trial 1 was conducted to assess salinity tolerance without acclimation when putting Black carp fingerlings directly from fresh water into treatments with different salinity concentration of 0, 5, 10, 13, 15, 17, 20‰; trial 2 was designed similar to trial 1 but fish was acclimated in brackish water before putting into different salinity concentration treatments. The results showed that non-acclimation black carp have 100% survival rate at the salinity of 13‰, but 100% mortality after 102 hours at 15‰, 12 hours at 17‰ and 4 hours at 20‰. Similarly, in the trial 2 with acclimation condition, Black carp were alive 100% at the salinity 13‰ and died quickly at higher salinity levels. Comparison of trial 1 and trial 2 in both condition revealed that Black carp could adapt and grow well in the arrange of salinity from 0-13‰, but quickly died without acclimation at 15‰ and showed no significant differences at 17 or 20‰. The growth rate of Black carp fingerlings in salinity 0‰ was highest with7,9a ± 0,61(gram/fish/week) and in lowest in 13‰ salinity (5,6c ± 1,12 (gram/fish/week). Histological observation indicated that there was no change in shape and structure of gills and kidney at the salinity of 0, 5, 10, 13‰, but at the 15‰ fish gills were dehydrated and shrinked and the kidney was clustered.
Histopathological features of tilapias cultured in Nothern Vietnamese provinces naturally infected with Streptococcussp.

Truong Dinh Hoai, Nguyen Vu Son, Nguyen Thi Hoai, Nguyen Thi Mai Phuong, Nguyen Thi Hau

Received: 13-05-2014 / Accepted: 30-05-2014
This study was implemented to clarify some histopathological characteristics of tilapia naturally infected with Streptococcus sp. cultured in freshwater ponds in Northern Vietnamese provinces during summer of 2013. Infected tilapias (n=46) showing symptoms of dermal haemorrhage and exophthalmia were collected at 9 fish farms in Hai Duong, Ha Noi and Ha Nam provinces and examined for both gross lesion and histopathological signs. Internally, the most consistent gross findings were haemorrhage and swelling of liver, spleen, kidney, heart and intestine as well as pale coloured liver and splenomegaly. Fish occasionally exhibited the accumulation of fluid within the abdominal cavity, epicarditis, and peritonitis. Histopathological examination revealed systemic bacterial dissemination and infiltration of bacteria-laden macrophages. The cornea was damaged and invaded by bacteria. Haemorrhage, granuloma formation and necrosis were detected in the infected areas of the liver, spleen, kidney and gills. Microscopical examination confirmed the presence of severe congestion in these ograns, especially spleen and kidney. Brain lesions were present occasionally. The results indicated that infected fish exhibited obvious and systemic histopathology.Adverse environmental factors during the hot season played a certain role in the formation of lesions and outbreak of this disease.
Some Biological Characteristics of Scatophagus argus(Linaeus, 1776) collectedin Can Gio District, Ho Chi Minh City

Nguyen Xuan Dong

Received: 02-07-2012 / Accepted: 12-09-2012
A study was carried out from 01/2010 to 06/2012 on 510 specimens of Scatophagus arguscollected in the canal of Can Gio District, Hochiminh City to identify some biological characteristics of this species. The biological characteristics observed included weight and length (120 specimens); age (30 specimens); male to female ration (120 specimens) reproductive characteristics (180 specimens), food composition in the intestine (60 specimens).. The results showed that the mean ofexploitable size was 88.71 ± 4.36 mm; absolute fecundity power was 289,797 ± 23,297eggs;relative fecundity was 2,772 ± 442 egg/g per female. This species is well known because of high exploitation, valuable food supply and economic value in this area. Beside economic value, it is also used asr ornamental fish. The study showed that this species can live in many kind of environment withfood diversity, etc.

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