Collaboration for Agricul
ture and Rural Development
(CARD)
Program
306
DEMONSTRATION OF SNAKEHEAD FISH IN TANKS AS A NEW MODEL OF
THE TRADITIONAL VAC SYSTEM TO REDUCE ORGANIC POLLUTION AND
IMPROVE INCOME FOR FARMERS IN THE CENTRAL COASTAL VIE
TNAM
Project title:
Improving traditional integrated farming systems (VAC)
-
a new livelihood option for
poor farmers in the coastal communities
Project c
ode
:
CARD
027/07 VIE
Author(s):
Võ V
ăn B
ình
1
, Đào Văn Phú
1
, Nguy
ễ
n Quang Chương
1
, Mai Văn Tài

In this project snakehead
fish (Channa maculatus) cultured in tanks and fed partly on earthworms,
resulted in an increase in income generation for farmers. The results have shown that the fish growth
rate was relatively high, reaching 700 g/fish after 5 months. The FCR for the en
tire production cycle
was 5.22, 4.75 and 6.14 in demonstrations in Thanh Hoa, Ha Tinh and Quang Tri, respectively. Water
quality remained within the acceptable range for fish health with NH3 and NO2 levels in the tanks
being significantly lower than those
in ponds. Economic analysis indicated that there was a high net
profit in all demonstrations with a ROI of 71%, 104% and 41% in Thanh Hoa, Ha Tinh, and Quang
Tri respectively.
The results demonstrate that culture of snakehead fish in tanks fed a partia
l diet of earthworms can
increase income to farmers thus other farmers in the region could benefit from adoption of the model.
1.
Introduction
Integrated farming systems encompassing
gardening, fish pond and livestock pen (under
Vietnamese acronym VAC
) is the most
popular practice in the rural communities of
Vietnam and other countries in Asia including
China (Vincke, 1997). This farming model is
very efficient in terms of recycling of the
materials in the system (Bilard et al., 1990).
However, the pro
ductivity of the aquaculture
(pond) component is quite low ranging from a
few hundred kilograms to an average 1,500
-

VAC, manures from husbandry or by
-
product
of horticulture are used for the c
ulture of
earthworms. The earthworms produced are
then used as food for high value fish species
cultured in tanks and the faeces of the worm
is used as fertilizer.
This article presents the results from
demonstration implementation of the Improved
VAC f
or the project CARD 027/07VIE. It
focuses on the snakehead cultured in tanks fed
with trash fish and earthworms. Examination
of fish growth rate, the water quality in tanks
and economic analysis of the demonstrations
are included.
2.
Materials
and methods
The demonstrations of the Improved VAC
were implemented in three middle provinces of
the country: Quang Xuong
-
Thanh Hoa,
Thach Ha
-
Ha Tinh and Trieu Phong
-

worms and a vegetable garden (Figure 1). The
fish tanks were surrounded with synthetic
polymer nets up to 2 m in height to prevent the
fish “jumping” out of the tanks when it rains.
Indicators
to assess efficiency of an Improved
VAC include culture water quality and profit
generation compared to a traditional VAC.
Water quality is evaluated by using parameters
such as temperature, DO, NH3, NO2, NO3,
BOD, H2S. In traditional VAC these
parameters
are usually at the high end of
acceptable values in the range for growth for
aquatic animals.
Fig 1.
Flow of materials in an Improved VAC:
Manures from animal husbandry are not
directly released into fish ponds. Instead
manure is used for e
arthworm culture.
During the production cycles, samples were
collected for water quality analyses. The
sampling was conducted in different positions
in tanks, that is, close to the water inlet and
outlet and in the centre part of the tank. In the
ponds t
wo samples were taken, that is, near to
the pump and in the centre of the pond.
Samples were then tested for NH

Garden (mainly
vegetables)
Pum
Manures for husbandry
or bypr
oduct of
horticulture
Cattle/pig/chicken
shed (manures
released)
Earth worm to culture
Semi
-
bio
filter
Fish pond
(or well to get
water)
Concret
e tanks
20m
2
Water circulated
after treated
Earthworm shed
(12
–
30 m
2
)

fed a combination of trash fish and earthworm
(with ratio of 50:50). However, the condition
factor K (K = W*100/L3) of the fish fed the
combined feed was higher than the fi
sh fed on
trash fish only (1.20 compared to 1.12). This
indicates that earthworms are suitable food for
snakehead.
Food conversion rate (FCR) was calculated for
the whole culture period in the three
demonstrations in Thanh Hoa, Ha Tinh and
Quang Tri. Thes
e were 5.22, 4.75 and 6.14
respectively. In the beginning of the
production cycle, that is from fingerling to 300
g/fish, the FCRs for the combination feed of
trash fish and earthworm (50:50) were 3.13;
3.66 and 4.11, respectively.
Interestingly, in Ha Tin
h the Improved VAC
system was managed by well educated persons
(both husband and wife were master and
bachelor degrees) and the survival rate in this
province was higher (97%) than in Thanh Hoa
(92%) and Quang Binh (87%) where system
managers had less for
mal education. This
suggests that system knowledge and
understanding could be an important factor in
the success of the operation.

between 0.36
–
0.66 mg/l and 0.004
–
0.03
mg/l, respectively (Figure 3).
Fig 2
. Growth rat
e of snakehead fish in tanks in the
Trieu Phong
–
Quang Tri Improved VAC
demonstrations
Võ V
ăn B
ình,
Đào Văn Phú, Nguy
ễ
n Quang Chương, Mai Văn Tài,
Ravi Fotedar &
Jane Fewtrell
309
Fig 3.
Comparison of
total Ammonium and NO2 in ponds and in
tanks during the production cycle in the Quang Tri demonstration.
For snakehead, the concentration of dissolved
oxygen does not play such an important role as
many for other fish species due to the fact that
they p

original in production cycle are presented in
Table
1.
Table 1.
Non
-
nitrogenous water quality measured during the culture of snakehead in Trieu Phong
–
Quang Tri. (P = Pond, and T = Tank)
Water quality parameters
Sampling months
Apr
May
Jun
Jul
Aug
Sep
P
T
P
T
P
T
P
T
P
T
P
T
Temperature (°C)

31
.
0
27
.
9
pH
7.9
7.8
8.3
7.7
7.8
7.9
8.5
7.6
7.8
7.4
7.7
7.7
DO (mg/l)
5.5
4.2
4.1
3.4
4.0
4.1
3.0
3.4
3.4
4.3

.
6
8
.
6
8
.
3
8
.
2
These parameters we
re well within the
favorable ranges for snakehead growth.
However, it is important to monitor and
control these parameters as they (particularly
temperature and pH) influence the
concentration and availability of the
nitrogenous parameters. Values of DO an
d
hardness were low, ranging between 3.4
–
4.4
mg/l and 6.5
–
8.6 respectively.
3.3
Economic analysis
Economic analyses have shown a good profit
from all demonstrations, regardless of the fact

depreciation (10.3%) and cost of the
fingerlings (8.2%). Earthwo
rms replaced a
large portion of the feed so feed costs would
have been higher using the traditional VAC.
Table 2.
Economic analysis
–
detail of input
and output for the demonstration in Th
ạ
ch Bàn
–
Th
ạ
ch Hà
–
Hà T
ĩnh
Expenditure
Value (VND)
Tank deprecia
tion (2 tanks x
20 m²)
1.000.000
Pump cost
150.000
Pumping cost (for
circulation)
400.000

20
Days of culture
147
139
158
Output (VND million)
8,095
19,851
10,368
Output (VND million)
4,766
9,698
7,334
Net profit (VND million)
3,392
10,153
3,034
Return on Investment (ROI)
0,71
1,04
0,41
3.4
Poten
tial of snakehead culture in
tanks
3.4.1
Advantages and disadvantages
There are several advantages
of culturing
snakehead in tanks:

areas, for example in Quang Tri, water that
meets the standard of quality for
aquaculture is scarce,
therefore effective
recirculating systems would be beneficial in
such areas.
5)
Snakehead can be stocked in tanks at high
density. For example stocking densities of
up to 50
–
70 fish/m² are possible and can
give productivity of 40
–
60 kg/m² without
cr
eating poor water quality in the system.
However, the culture in tanks also has some
disadvantages. The fish are easily harvested
which may lead to problems with theft, which
is common in rural areas. Also, the culture of
snakehead in tanks requires relati
vely
advanced technology, so farmers must be
trained so that the system operates efficiently
an
d costs are kept to a minimum.
3.4.2
Environmental aspect
a.

in Thanh Hoa and Ha Tinh.
b.
Surrounding environment
Culturing snakehead in tanks has three major
advantages over pond aquaculture from an
environmental impact perspective;
1)
Less effluent is released into the
environment and, if release is necessary, it
is generally of a less polluting nature.
2)
Less water is required which is beneficial
in areas
of limited water supply.
3)
Less physical damage to the environment
resulting from construction.
Furthermore, culturing snakehead in tanks is
clean and is not associated with the bad odor
that can accompany animal husbandry.
3.4.3
Economic aspect
The ec
onomic efficiency of snakehead culture
in tanks is assessed based on the margin of the
production cost and production value at
market. Unlike many fish species, the price
gap of snakehead between farm gate and end
users is not very high because snakehead c
an

Water quality parameters tested during
the culture indicated a suitable range for
growth of aquatic animals, including for
snakehead fish.
Võ V
ăn B
ình,
Đào Văn Phú, Nguy
ễ
n Quang Chương, Mai Văn Tài,
Ravi Fotedar &
Jane Fewtrell
312
Võ V
ăn B
ình,
Đào Văn Phú, Nguy
ễ
n Quang Chương, Mai Văn Tài,
Ravi Fotedar &
Jane Fewtrell
313
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ẩn Nh
à Nư
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-

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) to
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