Ministry of Agriculture and Rural Development

COLLABORATION FOR AGRICULTURE AND
RURAL DEVELOPMENT (CARD)

002/05 VIE
Technical and economic feasibility of applying the
Better Management Practices (BMP) to household
aquaculture in Vietnam MS 6: BMP training manual
ENVIRONMENT MANAGEMENT IN AQUACULTURE

Mai Van Ha
Nguyen Duc Binh
Research Institute for Aquaculture No.1
Bac Ninh, 2007
INTRODUCTION 4
1. ENVIRONEMNT MANAGEMENT IN POND AQUACULTURE 4
1.1. Why environment management 4
1.1. What influences water quality 4
1.2. Environment management of culture area and ponds 5

2+
, Fe
3+
) 10
3. MEDTHODS AND ENVIRONMENTAL STANDARDS 11
3.1. Methods of water quality analysis and measurement 11
3.2. Environmental standard/norm in aquaculture 11
4. SAMPLING STRATEGY AND PRESERVATION METHOD 12
4.1. Critical rules of sampling method 12
4.2. Sampling procedure 12
5. EFFECTS OF ENVIRONMENTAL FACTORS TO SHRIMP HEALTH 13
5.1. Weather and climate condition 13
5.2. Pond characteristic 14
5.3. Effects of weather condition on environment of shrimp ponds 14
6. ATTENTIONS ON SHRIMP CULTURE MANAGEMENT 14
6.1. Geographical location and environment 14

2
6.2. Culture management 15
7. POND PREPARATION 15
7.1. Lime utilization 15
7.2. Use of algicide 16
7.3. Treatment of in-pond produced substances 16
7.4. Disinfection 17
7.5. Removal of Plankton and benthic organism 17
7.6. Water color induction fertilization 18
8. REFERENCES 193

agents
+ Poor water quality results in poor growth of culture and more disease germs.
Water quality management is to minimize risk of water pollution (limited toxic
subtances and disease germ)
1.1. What influences water quality
+ Weather condition (rainy, sunny, stormy)
+ Bottom soil property: sand/dy, mud/dy.
+ Human- origined influences

4
1.2. Environment management of culture area and ponds
* What water parameters needs monitoring
+ Pond area, water deapth
+ Transpearency (by algae density)
+ pH, alkalinity, salinity
+ Dissolved oxygen (DO)
+ Toxic gases: NH
3
, NO
2
, H
2
S, CH
4
+ Organic sediments: assessed via content of COD and BOD
+ Nutritional form: NH
4
, PO
4
* Where to monitor within culture area


+ Algal community
+ Light panitration
In shrimp ponds suitable algal density of more than 2 mil.
cells/l, equavilant to transparency of 10 - 40 cm.
Secchi disc
In natural water body, less algal community obsered,
normally less than 1 mil. cells/l, if no alluvium and colloid
present water clearness up to 100 cm. Suitable transparency in aquaculture is of 25-40 cm.
Secchi dics is used to measure water transparency
2.4. Water color
Water colour experienced from:
+ Sand, alluvivum, colloid, .
+ Plankton organism: mainly algae
- Cyannophyta causes water greeny,
- Euglenophyta cause brownish yellow,
- Dinophyta/ Pyrophyta causes brown or blackish brown colour.
- Chrophyta, bacillariophyta experience blue colour
- Organic ditritus: blackish and stenchy.
What water colour influences water quality
+ It really depends on what is the constitution of warter colour. Water with greater alluvium,
organic sediment, phytoplankton has higher nutrient level.
+ If scum of any form and colour appears on the water surface there shoule be a need to
remove or water exchanged.
Giving a frequent observation on water color as it is an indication of positive or negative
message resulting to a further right remediation and treatment.
2.5. pH
pH of of any water falls into 1- 14
+ Acidic water: pH < 6,5
+ Neutral water: pH from 6,5 – 8,5

The role of DO to aquatic animals
+ Consumed in all organic oxidation and toxic gases degeneration
+ DO should maintained at more than 5,0 mg/l.
+ A suggested algal density of 2 – 5 mil./l could balance DO at a right level in water.
+ Phytonsynthesis by aquatic plant and alage causes significant diual fluctuation of DO,
minimum level of pH falls at 4 – 5 AM while highest value can be recorded at 1-2 PM.
2.7. Salinity
Salinity, mainly known as NaCl, gives suitable concentration for many aquaculture species at
15-25‰
2.8. Alkalinity

What constitutes alkalinity
+ Alkalinity measured as mg CaCO
3
/l indicates concentration of ions HCO
3
, CO
3
2-
, OH
-

present in water.
+ Hardness as mg CaCO
3
/l is measured by ion level of Ca
2+
và Mg
2+.


Nitrogen nutrient can be of: NH
4
, NO
2
, NO
3
-
+ NO
2
can be easily transformed to NH
4
or NO
3
depending on DO level and microoganism.
+ NH
4
and NO
3
-
can be directly uptaken by phytoplankton community, especially by
microalgae
Where they comes from:
Nitrogen fixation bacteria (symbiosis to phytoplankton or water hyacinth)
Biological decomposition of organic mater including detritus and dead aquatic organisms
to produce inorganic nitrogen as following: Organic nitrogen- > NH
4
Æ NO
2
Æ NO
3

2.12. Amonia (NH
3
)
+ NH
3
is generated during decomposition of rich
nitrogen compound.
+ In alkaline water, all NH
4
will be converted into
NH
3

NH
3
+ H
2
O <===> NH
4
+
+ OH
-
Possible impacts by NH
3
+ NH
3
is really toxic to aquatic organisms, while
NH
4
+

3
-
will be reduced to NO
2
-
.
+ Pond of well- management and aeration, NO
3
-
level is normally high and low NO2; and vi-
versa.
What influences
+ NO
2
-
level is an indicates of pond condition: poor water quality. Low DO and pollution.
+ NO
2
-
can even be toxic to culture species at quite low concentration of 0,1 mg/l.
+ NO
3
-
is harmfulless to aquatic anaimals
2.14. Hydrosunfure (H
2
S)
Where it comes
+ Mainly from decomposition of dead aquatic organisms
+ Anoxic organic decomposition

3

+ Coastal soil and tidal zone of high FeSO
4
.
Influence in water environment
+ Water dissolved ferrous compounds to release ion Fe
2+
, Fe
3+
+ Solvency of iron compound is higher in acidic environemnt (low pH)
+ In alkaline environment iron ions will form precipitated hydroxyte.
Remediation to discard iron
+ Water aeration for precipitation forming on bottom that required to remove in the and of
production cycle.
+ Liming will lead to precipitation down to pond bottom 10
3. METHODS AND ENVIRONMENTAL STANDARDS
3.1. Methods of water quality analysis and measurement

3.2. Environmental standard/norm in aquaculture
Or. Water parameter Unit Norm
1 Water temperature
o
C 25 – 33
2 Transparency cm 25 – 40
3 Water depth m 1,2 - 2,0
4 Water colour Green/Yellow/Greenish
yellow
5 pH 7,5 - 8,5
6 DO mg/l > 5,0
7 Alkalinity mg/l 80 – 120
8 Satlinity
‰
15 – 25
9 COD mg/l 10 – 20
10 BOD mg/l 5 – 10
11 NH
4
+
mg/l 0,5 - 1,0
12 PO
4
3-
mg/l 0,3 - 0,8
13 NH
3
mg/l < 0,10
14 NO
2
4.2. Sampling procedure
Preparation step
+ Sampling tools preparation (tools, chemical substances, machines, test-kit, sample botle
container).
+ Books and pens are necessary
Sampling step (on- field)
+ Taking a view and sellect presented position for sampling
+ Collecting water samples, fix these samples and measure parameters which can be done on-

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field (DO, temperature, pH, transparency ).
+ Making notes any ponds- related information (name, location, name of sampling position
and characters of the position). Recording weather condition (sunny or rainny, wind
direction, clouds ). All in one a well-designed data recording book.
Sample analyzing.
+ Depend on distance, if it is not far form laboratory, the samples should be taken to the lab
for analyzing as soon as possible.
+ Samples can be analyzed on-field if it is far from Lab, in this case included appropriate
devices required.
+ If it is not done immediately, the samples should be fixed carefully and kept in cool
condition before taking to the laboratory.
Sample preservation

Effect of hot weather
+ Hot weather causes of high water temperature, anerobic disitegration process of organic
substances in pond, especially at the bottom of pond, happens quickly. This process produces
toxic in the bottom (20 cm in sediment layer) such as: H
2
S, CH
4
NH
3
, NO
2
, these gases are
harmful for shrimp health.
To NH
3
: Level of NH
3
is directly proposional to temperature and pH
To H
2
S: Level of H
2
S is inversely proposional to temperature and pH.
+ Greater development rate of microorganism: WSSV, MBV, YHV
Effects of heavy rain in the early stage of crop
+ Rain in early stage has serious effects on crop, it deteriorates environemental quality:
chaning pH, salinity,, temperature causing stress on culture species, more susceptibile to
disease infection. Toxic H
2
S releases from sediment to water column, DO level decrease and

7.1. Lime utilization
Lime is used in the purpose of decontamination,disinffection and increasing pH and making
pH stable (buffering. L systembased on Carbonic - Bicarbonate – Carbonate balance). Liming
dose is as following: calculated base on pH of soil bottom
Table 1: Ralationship between liming amount and pH of soil bottom (kg/ha)
Soil pH CaO Ca(OH)
2
CaCO
3
CaMg(CO
3
)
2
7,0 - - 500 500
6,0 500 700 1000 1000
5,0 750 1000 1500 1500
4,0 1000 1200 - -
Table 1: Lime using between two crops following pH level
CaO or Ca(OH)
2
pH
kg/ha
4,0 - 4,5 1500
4,5 - 5,0 1250
5,1 - 5,5 1000
5,6 - 6,0 700
6,0 - 6,5 600
6,5 - 7,5 500
Some kinds of lime used aquaculture
1. CaCO

dead organism, detritus), anoxic decomposition of these will produce toxic substaneces such
as H
2
S, NH
3
, CO
2
, NO
2
to aquaculture species
Economic and simple way to improve water quality is to exchange with clean water, and
experience oxygenation.
Use of Zeolite: It is mineral compound of differnet mental oxide that can absorb toxic
substance. Application can follow:
Table 2: Zeolite amount used in shrimp pond
Used rate Zeolite (Daimentin)
Parameter
(mg/l) (kg/ha/week)
Fe total 0,20 - 2,00 200 - 2000
H
2
S 0,50 - 2,00 500 - 2000
NH
3
, NH
4
0,02 - 2,00 20 - 200
NO
2
, NO

liters of water, spreading evently on pond bttom
surface at late afternoon.
Disinffesion of storage pond/reservoir
Use of following treatment:
+ Chlorine (Cl2) 10 - 15 kg (ot liter)/1000 m
3

+ Formol 20 - 30 liters/1000 m
3

+ BKC (Benzalkonium Chloride) 0,5 - 0,7/1000 m
3
in three consecutive days.
+ Mizuphor 100/1000 m
3
in three consecutive days.
It is critical that applied chemical need to totally decompose, so after treatment wait for some
time before getting water into ponds. Practically putting some fish/shrimp in to pond water-
filled bucket in 24 hours if they still keep alive, so free toxic water recognized.
For Saponine (with Cyanua) can be used to kill trash fish/predator at a dose of 100 – 200
kg/ha. The product of TeaSeed Cake or Tea Seed Powder containing up to 7% of Saponine is
being popularly used world-wide.
7.5. Removal of Plankton and benthic organism
Plankton and benthic organism are ubiqutous available regarding time and spaces. In the
favourable condition they can even develop bloomly (rich in nutrients, ligh attenuation, water
temperature and salinity). Unwanted organism will compete nutrient leading poor growth of
algal fauna as natural food for culture species, interfere locomotion. Moreover, biofouling
can be really a problem for culture species’s health. Decomposition of dead plankton and
benthic community will generate toxci gases in water.
General application


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8. REFERENCES
ASEAN - Canada, 1993. Marine Environmen Quality, Perspectives on ASEAN
Criteria and Monitoring, Vol I, EVS Environment Consultants Ltd. and Indonesian
Institute of Science
Boyd, C. E. (1990). Water Quality in Ponds for Aquaculture. Alabama Agricultural
Experiment Station, Auburn University, 114 Birmingham Publishing, 482 p.
Nguyễn Đức Hội, 2002. Bài giảng “Quản lý chất lượng nước trong nuôi trồng thuỷ
sản”. Xuất bản nội bộ của Viện nghiên cứu nuôi trồng thuỷ sản 1.
TCVN 6774: 2000 Chất lượng nước - Chất lượng nước ngọt bảo vệ đời sống thủy
sinh.
TCVN 5942: 1995 Chất lượng nước - Tiêu chuẩn chất lượng nước mặt.
Standard Methods for the Analysis of Water and Waste water. American Public
Health Associatin- APHA, 1998. New York.

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