1

Ministry of Agriculture & Rural Development

Project Progress Report SECOND SIX-MONTHLY REPORT

4
th
July, 2008

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Table of Contents

1. Institute Information ___________________________________________________ 3
2. Project Abstract _______________________________________________________ 4
3. Executive Summary ____________________________________________________ 4
4. Introduction & Background _____________________________________________ 6
5. Progress to Date _______________________________________________________ 8
5.1 Implementation Highlights ________________________________________________ 8
5.2 Smallholder Benefits_____________________________________________________ 19
5.3 Capacity Building _______________________________________________________ 20
5.4 Publicity_______________________________________________________________ 20
5.5 Project Management ____________________________________________________ 20
6. Report on Cross-Cutting Issues__________________________________________ 20
6.1 Environment ___________________________________________________________ 20
6.2 Gender and Social Issues _________________________________________________ 21
7. Implementation & Sustainability Issues ___________________________________ 21

In Australia: Team Leader
Name:
Richard Bell
Telephone:
+61 8 93602370
Position:
Professor
Fax:
+61 8 93104997
Organisation Murdoch University Email: [email protected]

In Australia: Administrative contact
Name:
Richard McCulloch
Telephone:
+61 8 93607566
Position:
General Manager
Fax:

Organisation
Murdoch Link
Email:
[email protected]

In Vietnam
Name: Cao Van Phung Telephone: +84 71 861452
Position:
Head, Soil Science Dept.
Fax:

3. Executive Summary
Questionnaires for the baseline study were formulated in consultation with researchers of
Can Tho University, and with extension officers in Can Tho city and An Giang provinces. In
total 240 questionnaires of stakeholders (rice farmers and fish farmers) were collected (2
districts/site). The results showed that all stakeholders were concerned about surface water
pollution because of its effects on their business sustainability and livelihood. There were
about 15-24 % of the farmers (including both fish and rice farmers) stating that water quality
is bad. There are only 3-8 % of fishpond holders having settling ponds, 15-24 % of them
practice waste recycling on paddies and the rest discharge directly to the waterway. In
Cantho, farmers practicing fish culture are richer, have more formal education and are
younger than those carrying out rice cultivation. However, about 15 % of fishpond holders
are recent migrants who have bought or rented lands from local farmers. In An Giang, fish
farmers had similar age and education profiles to rice farmers suggesting that here fish
farming was carried out as a diversification of farm activities. Impacts reported on water
quality include greenish-black colour, bad smell, high turbidity, causing itching on contact.
Moreover, farmers raising fish recognised that percentages of disease-infected fish were
much higher (about 15%) than before (< 5 %). The demand for effective and economical
solutions for control of water pollution is the first priority of stakeholders. Only 10 % of fish
farmers surveyed in An Giang and 25 % of those in Cantho expressed the intention to
increase production in the future. Notwithstanding their concern about water quality, few
expressed an intention to construct settling ponds (3-7%) in the future.

The survey of farmers’ practices on fishpond waste treatment was completed during the dry
season 2007 at 2 sites (An Giang province and Can Tho city). Most (68-80 %) of the wastes
(liquid and solid) are pumped directly into waterways (rivers or canals). In the case of
fishponds located nearby big rivers (Tien and Hau), waste is apparently diluted by the large
volume of water flow and it is not reported to cause much problem in comparison with
In total, 240 questionnaires of rice and fish farmers were collected (2 districts).
Stakeholders were concerned about surface water pollution because of its effects on their
business sustainability and livelihood. There were about 15-24 % of the farmers

during the wet season 2007 at the experimental farm of Cuu Long Rice Research Institute.
Three dosages of waste at the rate of 1, 2 and 3 tonnes/ha were applied in combination with
1/3 and 2/3 dosages of inorganic fertilisers. The 100 % rate of inorganic fertilisers (60N-
40P
2
O
5
-30K
2
O) served as the control. There were no significant differences in rice yields
over all treatments. This indicated that uses of solid waste from fishpond can save money for
farmers by reducing fertiliser inputs. The experiment was repeated in the dry season 2008,
and produced similar results. That is, 1/3
rd
to 2/3
rd
of the inorganic fertiliser recommended
for rice can be omitted when applying fishpond solid waste at 1-3 t/ha.

Fifteen isolates of Pseudomonas stutzeri were selected from liquid and solid waste of catfish
ponds located along the Tien river, in the Mekong Delta, Vietnam using SW-LB medium
(artificial seawater Luria-Britani medium) supplemented with 10 mM NH
4
and NO
3
. Eleven
isolates were identified as Pseudomonas stutzeri based on similarity of PCR-16S rRNA using
universal primers and specific primers. Four isolates were effective in lowering soluble N
(NH
4

2007 with 17 participants from the provinces of Cantho, Vinh Long, An Giang and Dong
Thap. Participants were from fisheries, agriculture extension and natural resources
management positions.

4. Introduction & Background
Fishpond aquaculture is as a major industry in the Mekong Delta. However, wastewater and
solid waste discharge from fish ponds is causing pollution of canals and rivers harming the
quality of water used for household purposes and threatening the future of the aquaculture
industry itself. There is a clear and urgent need to develop strategies for reducing waste
discharge from fish ponds so that the fishpond aquaculture industry can continue to support
income diversification in the Mekong Delta, while complying with the water quality
discharge standards outlined in Vietnamese law and regulations (Ministry of Fisheries
2006)
1
.
Water in fish ponds is replaced frequently generating large quantities for disposal or re-use.
Currently wastewater is mostly discharged into communal rivers and canals, but this has
caused significant downstream water pollution, such that most of the aquaculture is now
located in the headwaters of catchments. In order to reduce pollution, National
Environmental Law introduced in 2005 prohibits direct wastewater discharge into rivers and
canals. Offenders may either be fined or their operation closed until compliance is achieved.
In addition annual emptying and cleaning of solid waste from the base of fish ponds is
essential to control the spread of diseases among fish. This produces an organic-rich slurry
comprising about 35 % solids. Discharging this slurry into communal waterways is also
prohibited under the law. However, there appears to be poor compliance with the law by
operators of fish ponds. Strict compliance with the law without cost-effective treatment and
recycling strategies would have a crippling effect on the fishpond aquaculture industry. It is
critically important to develop effective strategies for fishpond operators so that they can
treat wastewater and solid wastes to meet discharge standards without large costs.
While there is widespread acceptance that water pollution from fishpond discharge is

producers in the Mekong Delta. In addition, technologies to be developed will improve
natural resources management by decreasing water pollution from uncontrolled discharge of
fishpond waste water and solids into rivers and canals. The overall Project objective is to
improve the sustainability of fishpond aquaculture production and water quality in the
Mekong Delta. Specific Project objectives are:
• Develop effective treatment strategies for wastewater and solids from
fishponds before discharge to reduce water pollution;
• Develop resource recovery and re-use strategies for waste water and solids
from fish ponds including land application and novel end uses;
• Increase stability of household income from fishpond aquaculture through
encouraging diversification of production and markets in the Mekong Delta.
This project targets fishpond aquaculture, not other types of aquaculture such as cage
aquaculture and shrimp aquaculture. Cage aquaculture is declining in importance due to
rising costs and riskiness of the production system compared to pond culture. Other studies
have examined shrimp aquaculture in brackish water environments (Be, 1997). Shrimp
aquaculture is also under threat due to environmental impacts. Hence, there are lessons to be
learnt from other forms of aquaculture, in particular the need to address environmental issues
that can impact on the sustainability of the industry even when economics for it are
favourable.
Fishpond aquaculture is practiced by three main groups in the Mekong Delta: farmers using
the VAC system to recycle waste water and solid wastes from fish ponds; small farmers who
have both fish ponds and crop land but without integration of these components of the farm;
specialist producers who essentially use all of their land for fish ponds. The VAC system
already practices re-cycling of wastewater and solid waste to recover nutrient resources. In so
doing the level of pollution caused by water discharge is probably decreased. However, there
appears to be little evidence to demonstrate the benefits of the VAC system for downstream
water quality. The present project will assess the impact of the VAC system on water quality
in downstream canals, and as necessary examine modifications to the recycling of
wastewater and solid waste in order to meet water quality standards for discharge. The
second group of producers comprises small farmers who have a few fish ponds within a farm

(Table 1, 2). Results showed that all stakeholders were concerned about surface water
pollution because of its impacts on sustainability of production and livelihoods. There were
about 15-24 % of the farmers (including both fish and rice farmers) stating that water quality
is bad. Only 30-55 % of farmers were fully satisfied with the quality of water available for
fish farming. In Cantho, 80 % of farmers accessed household water from public water
supplies and groundwater and in this province 83 % of farmers were satisfied with water
quality for household use. However, in An Giang, where 57 % of farmers used river water
for household purposes, the level of satisfaction with water quality was only 36 %. Most
farmers (91 %) attributed poor water quality for household use to fishpond farming in An
Giang, but to fishponds (37 %), pesticide use in rice fields (15 %) and other causes (48 %) in
Cantho. Most farmers anticipated that water quality improved during the period of flooding
(September- November).

Farmers practicing fish culture are richer, had more formal education and were younger than
those carrying out rice cultivation, based on numbers of concrete houses, living commodities,
pumping machines and incomes. However, about 15 % of fishpond holders are recent
migrants who have bought or rented land from local farmers. Impacts reported on water
quality include greenish-black colour, bad smell, high turbidity, and skin itching on contact.
Moreover, farmers raising fish recognised that percentages of disease-infected fish is much
higher now (about 15%) than before (< 5 %). The demand for effective and economical
solutions for control of water pollution is the first priority of stakeholders. The investment
cost for raising fish is large and most of farmers lend money from either banks or their
neighbours hence they are concerned about threats to the viability of the operation.

Survey of farmers’ practices on fishpond waste treatment
: The survey of farmers’ practices
on fishpond waste treatment was completed during October-November 2007 at Cantho and
January-February, 2008 at An Giang province. Most (68-80 %) of the wastes (liquid and
solid) are pumped directly into waterways (rivers or canals). In the case of fishponds located
nearby large rivers (Tien and Hau), waste is apparently diluted by the large volume of water

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23
73
4

42
39
19

48
44
8
Water quality (%)
- Good
- Medium
- Bad

30
52
18

55
22
23

51
25
24


that one farmer constructed a sand bed filter with activated charcoal for the treatment of
waste water from fishponds by using a water recycling system. However, we have not been
able to inspect this system.

Concerning the use of bio-products for water treatment in catfish culture, nearly 50 % of
farmers at both sites used Vikong, BKC, Bioca, Yulai, Aquapure, Prawbac and some others
(Table 3). They also used antibiotics to control mainly bacterial diseases in the digestive tract
of catfish. Some common antibiotics like Amoxycilline, Cotrim, Penicilline, Kanamycine,
Oxamet, and Tetracylline had been used mainly by mixing into feeds in An Giang (96%) or
putting directly in water (40% of farmers in Cantho follow this method). According to
farmers, these antibiotics were very effective to control catfish diseases. Fortunately, almost
all of farmer used antibotics at recommended dosage. For sanitary purpose and control of
algae in fishpond, 93% of farmers in Cantho and about 66% in An Giang province applied

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copper sulphate, BKC, Vikong, chlorine, Juka and even salt or lime (Table 3). Among these,
BKC and chlorine were the most common chemicals which had been used both in An Giang
and Cantho.

Table 2: Quality of water for irrigation and for household use as a % for 240 respondents.
Items An Giang (%) Can Tho (%)
Water source for household use (cooking
& drinking)

River/ canal 57 17
Tube well 13 57
Public water supply 30 26
Water quality for household purposes
Good 46 80
Medium 18 13

draining out all water during harvesting of fish (Table 4). Dosages of lime and salt varied
from 300-400 kg/ ha/yr. Ponds are kept dried for 3-5 days before refilling with water for the
new crop of fish. More than 95% of farmers changed and/or added water to fish ponds
regularly (about 1/3 volume of pond) and there was about 50% farmers at both sites that
practiced cleaning of the bottom of the fishpond by pumping out sludge during time of
raising catfish. However, most farmers had to pump sludge out of their pond after harvesting

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fish (Table 11). The practice of discharge waste directly to water source caused water
pollution. Most of farmers had handheld pH meter to monitor water quality. Other ways to
detect water quality were by observation of water colour or smelling odour of water. If
oxygen is deficient, most fish will come to the surface of water in the early morning; farmers
will then know oxygen in fishpond is sufficient or not.

Table 4: Water management in catfish culture.
Items Cantho An Giang
Renewed fishpond (%) 100 100
Lime (kg/ha) 425 350
Salt (kg/ha) 325 300
Dried bottom of pond (%) 100 100
Days of drying 3.5 4
Added and/or changed water periodically (%) 98 100
Percentage of added or changed water 33 33
Water quality monitoring

pH 95 90
Color or odour 8 12
Ammonia and oxygen (from fish behaviour and odour) 62 65
Sludge discharged


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sites. In most case, disease can be controlled in Cantho as well as in An Giang at the rate of
92 and 82%, respectively.

During the dry season 2007, we conducted a study on “Effect of waste application on
rice yield in An Giang province”. We selected 32 paddies wherein 16 fields received waste
water through discharge from fishponds while the others did not. Results showed that rice
yields in fields receiving waste water were 0.8-1.0 tonnes/ha higher than those that did not
receive waste (Table 3). This might be due to high nutrient content in waste especially
available nitrogen, phosphorus, potassium as well as secondary and micronutrients (Table 4).
However, organic carbon content in paddies receiving waste was lower suggesting more
rapid decomposition of the organic matter in treated fields.

Table 6. Mean rice yields in paired farmers’ fields at Chau Phu and Phu Tan districts
supplied with fishpond wastewater for irrigation or river water. Values are means from 8
fields.
Treatments Chau Phu Phu Tan
Irrigation with wastewater 7,920 a 7,436 b
Irrigation with riverwater 6,898 b 6,613 c
CV% 6.1 6.1 Table 7: N, P, K and organic carbon in soils after harvesting rice in fields with and without
application of wastewater to crops.
Chau Phu Phu Tan
Soil properties
+ waste
water
- waste
water

% C % N % P % K
NH
4
+
NO
3
-N
(mg/kg)
Olsen P
(mg/kg)
Exch K
(mg/kg) % Fe % Mg % Mn
Cu
(mg/kg)
Zn
(mg/kg)
Ca
(mg/kg)
Cd
(mg/kg)
5 months
Pellet feed 4.64 0.23 1.13 266 49.2 194 3.61 0.06 0.05 35.7 107 162 3.2
SE 0.47 0.02 0.05 37.6 5.24 9.6 0.41 0.00 0.01 1.37 6.5 67.3 0.26
Overall
mean 4.98 0.32

1.13 276 48.1 216 3.90 0.06 0.05 34.6 111 134 3.1

mixing plus
pellets
Some farmers use
liquid waste from
fish ponds for rice
cultures
Phu Tan Large fishponds,
recent
development
Discharging
through gates to
small canal
Own feed
mixing plus
pellets
Controversies on
liquid waste
application on rice
Thot Not Large fishponds,
operating 8
years
Mainly to
canals, some
was discharged
on padi
Pellets and
own feed
mixing
Settling pond, tree
lot irrigation, rice

In addition depths across the canal and flow rate of water in the canal were measured.

Sampling occurred once per month for 5 months. Water samples were collected from
all points before discharge began and then starting 1 hour after discharge commenced.

Water quality measurements:
Chemical properties: pH, EC, BOD, COD, NO
3
, P, S,
Biological properties: E coli, Total coliform, Staphyllococcus, Salmonella.

However, a number of factors will be considered in sampling:
1. Control sites- Most catchments will have background inputs of pollutants to canal
water from rice farming, and human settlements. The background impact of these on

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water quality needs to be determined by water sampling at control sites beyond the
influence of fishponds. The location of the control sites will vary from site to site.
2. Low tide sampling- During low tide water drains out of the catchment and at this
time discharge of wastewater is most likely. Sampling should coincide with such
periods of discharge to capture the peak in pollution events.
3. High tide sampling- During high tide back flow of water from rivers and main
canals to small canals occurs. Refilling of fish ponds is likely during these times.
Sampling should also be planned to coincide with such periods of discharge to capture
the base load in pollution events.
4. Sampling protocols- Protocols should describe sampling locations (depth, distance
from bank), cleaning of sampling bottles, storage conditions for samples after
collection.
5. GPS positioning of sampling sites- To ensure sampling is repeated at the same
positions GPS coordinates should be taken for sites.

O) served as the control. There were no significant differences in
rice yields over all treatments. This indicated that uses of solid waste from fishpond
can save money for farmers by reducing fertiliser inputs. This experiment was
repeated during the dry season 2007-2008 at the same site. Results in the dry season
verified that yields of rice can be maintained with 1/3rd or 2/3rd of the recommended
inorganic fertiliser dose, when combined with 1 to 3 t of aquaculture solid waste/ha. A
third crop of rice has been planted on the plots with additional solids from the
fishponds.

Recycling of waste water for rice irrigation
:
Results of field experiments at Chau Phu indicated that rice yields of all treatments in
the wet season 2007 were not statistically different (Table 9). However, in the dry
season 2008 rice yields of T1 and T2 were highest and were statistically higher than

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the other treatments (T3, T4 and T5) (Table 9). The higher yields in T1 and T2 are
attributed to the acidity of soils in which phosphorus is a key factor for crop growth
(Cong et al. 1995). This explains why yields in T3 were low. Besides that, nitrogen in
T3, T4 and T5 was low and not sufficient to achieve potential yields for the dry
season. Rice yield in the wet season is usually lower than in dry season in the Cuu
Long Delta due to lower solar radiation (Hung et al., 1995). Analysis of soil, straw
and grain samples at harvesting time showed no significant difference among
treatments in concentrations of N, P and K (data not shown).

Results in Table 10 indicated that rice yields in T1 and T2 were the highest yield and
they were significantly greater than others. This suggests that irrigation by wastewater
from fishponds can save 1/3 of recommended N, and 1/2 of the recommended P and
K. By comparison, treatment T2 and T4 showed that further decrease in nitrogen
fertiliser resulted in reducing yield. T3 had the lowest yield because this treatment did


Water quality in fish ponds
: Water was collected from 12 fish ponds in Chau Phu and
Phu Tan districts. Results are still being analysed and will be fully reported in the
MSc thesis of Ms Wang in September 2008. 17
Microbial treatment of wastewater
: Excess soluble NH
4
+
- nitrogen (N) may
accumulate in fish-pond water used to produce catfish in the Mekong Delta and have
harmful effects on fish health as well as water quality after discharge. The aim of this
study was to explore the potential for reducing soluble N load in fishpond wastewater
using naturally occurring denitrifying bacteria. Fifteen isolates were selected from
liquid and solid waste of catfish ponds located along the Tien river, in the Mekong
Delta, Vietnam using SW-LB medium (artificial seawater Luria-Britani medium)
supplemented with 10 mM NH
4
and NO
3
. Eleven isolates were identified as
Pseudomonas stutzeri based on similarity of PCR-16S rRNA using universal primers
and specific primers. Four isolates were effective in lowering soluble N (NH
4
, NO
2


the tanks. Ozone treatment did not raise levels in wastewater above 0.14 mg/L, by
contrast with the higher levels of enrichment achieved in brackish water (0.36 mg/L).
Effects on water quality were mixed. No evidence of mortality of catfish was
observed in the ozone treated water regardless of fish size. Several laboratory-scale
experiments are planned to determine the effectiveness of ozone treatment in
oxidation of organic matter and disinfection of bacteria in wastewater.

Use of aquatic plants to improve water quality
: Aquatic plants in combination with
settling ponds may be an effective means of improving water quality before discharge
to canals. Two experiments were conducted by a BSc student from An Giang
University. In the first experiment, 5 types of aquatic plant (including water hyacinth)
were evaluated in still solutions, while in a second experiment a flow-through system
was used to determine effectiveness of species in improving water quality. Analysis

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of results is still under way but there does appear to be a decrease in soluble N and P
and a decline in total suspended solids in wastewater with aquatic plants growing in it.

Workshop on Land application of Waste 26-29 December 2007

17 participants attended the Workshop at CLRRI from 26-29 December. They were
from the provinces of Cantho, Vinh Long, An Giang and Dong Thap. Participants
were from fisheries, agriculture extension and natural resources management
positions.

The following hand out materials were provided to the participants:
 Application of Wastes to Land. A Literature Review. 81 pages. An
abbreviated version of the following report- McGowan, J., Pullumannapallil, P
and Bell, R.W. (2002). Application of Wastes to Land. A Literature Review.

applications on soil organic matter content and soil physical conditions: a
review. Nutr. Cycl. Agro-ecosystems 51, 123-137.

The workshop was run in Vietnamese, or with translation of English talks into
Vietnamese. In retrospect, it would have been more effective if more of the written
materials had been translated beforehand into Vietnamese. Some activities planned
had to be modified because the level of English reading was not adequate for the task.

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The critical review of journal paper was not feasible as the participants found the
technical English level too difficult to understand. Similarly the exercise on nutrient
budgets would have been improved if the spreadsheet had been in Vietnamese. We
have agreed to revise the spreadsheet to make it more easily understood to a non-
specialist, and translate it into Vietnamese for distribution to the participants.

Feedback from participants

The following comments were made about the workshop.
1. The VAC system seems ideal for treating the fishpond waste. (This was noted, but
it was pointed out that the CARD programme directed us to work mostly on larger
fishponds).
2. The workshop increased awareness of the environmental impact of fishpond waste.
3. Participants learnt a lot about soils and their relevance to land application.
4. The Excel nutrient budget calculator was considered a very useful tool for
providing advice to fishpond operators and farmers on how to manage nutrients when
applying wastewater to padi fields.

During the workshop, participants reported on farmer innovations in waste treatment.
 Some farmers use the compounds: AS3 and ADL. Further investigation will
be carried out to determine the nature and effectiveness of these compounds.

possibly 50 % in the case of P and K. However, omitting N and P fertiliser completely
caused depressed yield, indicating that the wastewater did not supply sufficient N and

20
P for crop requirements without some fertiliser. The technique on irrigating rice with
fishpond wastewater will be disseminated to farmers through the Departments of
Agriculture and Rural Development in Cantho and An Giang provinces.

Fishpond solid waste, when applied at 1-3 t/ha, also contains sufficient nutrients that
fertiliser rates can be decreased by 1/3- 2/3 of present recommendations without loss
of yield.

Capacity Building

Two MSc students from Can Tho University are now completing their theses on
Treating and recycling of solid and liquid waste from fishpond – both are due for
submission in September 2008. Both students are academic staff at An Giang
University and hence are in a position to transfer their knowledge to students of
environmental science at the university.

One BSc student of An Giang University is undertaking a study on the use of aquatic
plants to improve quality of fishpond waste water. Another BSc student of An Giang
University has commenced his thesis entitled “ Effect of waste discharge on water
quality”. A MSc of Canto University will commence shortly on a study designed to
calculate the nutrient budget for fields with fishpond waste application.

The workshop on Land application of Waste, held on 26-29 December 2007, was
attended by 17 participants. They were from the provinces of Cantho, Vinh Long, An
Giang and Dong Thap. Participants were from fisheries, agriculture extension and
natural resources management positions.

pollution because of its impacts on sustainability of production and livelihoods. About
14-25 % of the farmers (including both fish and rice farmers) reported that water
quality for fishpond farming is bad. Farmers practicing fish culture are richer, better
educated and younger than those carrying out rice cultivation, based on numbers of
concrete houses, living commodities, pumping machines and incomes. However,
about 15 % of fishpond holders are recent migrants who have bought or rented lands
from local farmers. Impacts reported on water quality include greenish-black colour,
bad smell, high turbidity, and skin itching on contact. In Cantho, 80 % of farmers
accessed household water from public water supplies and groundwater and in this
province 83 % of farmers were satisfied with water quality for household use.
However, in An Giang, where 57 % of farmers used river water for household
purposes, the level of satisfaction with water quality was only 36 %. Most farmers
(91 %) attributed poor water quality for household use to fishpond farming in An
Giang, but to fishponds (37 %), pesticide use in rice fields (15 %) and other causes
(48 %) in Cantho. Moreover, farmers raising fish recognised that percentages of
diseases infected fish is much higher (about 15%) than before (< 5 %). The demand
for effective and economical solutions for control of water pollution is the first
priority of stakeholders. The investment cost for raising fish is large and most of
farmers lend money from either banks or their neighbours hence they are concerned
about threats to the viability of the operation.
7. Implementation & Sustainability Issues
Issues and Constraints
None to report.

Options

The next priority of research is to demonstrate that improvements in canal water
quality are achieved when wastewater and solid waste is treated by application to rice
padi fields. This would provide the critical evidence that treatment strategies exist and
provide a basis for encouraging wide scale implementation of this treatment means in


Continue experiments on the use of liquid and solid waste for rice cultivation during
wet season 2008. The CLRRI experiment on application of fishpond solid waste will
be continued until crop 6 (it is presently growing crop 3). A new trial will be set up at
CLRRI to quantify the nutrient inputs from fishpond waste water so that a nutrient
budget can be determined for the treatments. Another new trial will be set up in Chau
Phu to more accurately define how much reduction in chemical fertiliser should be
recommended when using wastewater. It is also necessary to define the maximum
rates of solid waste from fishponds that can be safely applied without inducing
excessive vegetative growth and a risk of yield loss from lodging.

Determination of whether ozone treatment of fishpond wastewater can achieve
disinfection and oxidation of organic matter.

Determine the fate of N in wastewater when inoculated with Pseudomonas stutzeri
cultures. This is necessary to establish the mechanism of action of the Pseudomonas
stutzeri isolates.

Identify optimal conditions for vermicomposting of aquaculture solid waste through
Australian Youth Ambassador for Development assignment due for completion late
November 2008.

Conduct a training workshop on waste treatment. CLRRI will host the training course
at CLRRI for 15-20 participants. Professor Ho will visit in November 2008 to jointly
present the course with Dr Phung. Course notes provided by Professor Ho are being
translated into Vietnamese.

9. Conclusion
The investigations support the basis for the project by indicating that water pollution
is perceived to be a widespread problem in the fishpond industry itself. Moreover,