Collaboration for Agriculture and Rural Development CARD ProgramDEMONSTRATION OF SNAKEHEAD FISH IN TANKS AS A NEW MODEL OF THE TRADITIONAL VAC SYSTEM TO REDUCE ORGANIC POLLUTION AND IMPR
Trang 1Collaboration for Agriculture and Rural Development (CARD) Program
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 VIETNAM
Project title: Improving traditional integrated farming systems (VAC) - a new livelihood option for
poor farmers in the coastal communities
Project code: CARD 027/07 VIE
Author(s): Võ Văn Bình1, Đào Văn Phú1, Nguyễn Quang Chương1, Mai Văn Tài1, Assoc Prof
Ravi Fotedar2, Jane Fewtrell2
Project Implementing organisations:
1 Centre for Environment and Disease Monitoring in Aquaculture (CEDMA) – RIA1 2
Agriculture and Environment - Division of Science and Engineering-Curtin University of Technology, Australia
SUMMARY
In order to overcome the limitation of land available for aquaculture in the central costal region of Vietnam and to reduce organic pollution in traditional integrated fish farming, a new method was developed called the ‘improved VAC’ In traditional VAC systems the manure from farm animals is released into fish ponds whereas in the ‘Improved VAC’ the manure is used for earthworm culture The worm production is then used to feed high value fish species in tanks.
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 entire 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 partial 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 productivity of the aquaculture
(pond) component is quite low ranging from a
few hundred kilograms to an average
1,500-1,700 kg per ha per year (0,015-0,017
kg/m2.year) (Kumar et.al, 2003) Aquatic
species produced in the traditional VAC
systems carry a high risk of contamination with organisms such as E.coli and parasites Acinetobacter spp that were exposed to the high organic load of the VAC system for two months and isolated from composite water-sediment samples were found to have an increased resistance to oxytetracycline and sulfamethoxazole (Andreas Petersen et al., 2002) E.coli , isolated from mothers involved
in integrated fish farming were found to have increased antibiotic resistance compared to those isolated from mothers who were not ( Kalter, 2009)
Therefore, it would be beneficial for the traditional VAC system to be improved to
Trang 2enable increased productivity and reduce
potential organic pollution In the Improved
VAC, manures from husbandry or by-product
of horticulture are used for the culture 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 for 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 - Quang
Tri These sites are representative for three
socio-eco-systems The first site, Thanh Hoa,
is representative of a small household scale
(small garden and ponds with no artificial
aeration) The second site is for households
who have a higher standard of husbandry and
horticulture but no pond The third site was in
Quang Tri and is representative of households
with a large pond/s but poor water quality, and
basic horticulture and husbandry practices
The Improved VAC system includes 30 –
40m3 (height of 60 – 80 cm) of water in
concrete tanks or pond (100 – 300 m2), a
livestock pen with an area of 50-60m2 which
can produce manure for cultivation of earth
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 earthworm 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 two samples were taken, that is, near to the pump and in the centre of the pond Samples were then tested for NH3, NO2, pH,
DO and hardness by using test kits and laboratory analysis The results were interpreted in comparison with the traditional VAC and in accordance with the acceptable range for aquatic animals outlined in the National Standard for Water Quality (TCVN, 1995; 2000)
Snakehead (Channa maculatus) was stocked at density of 10 fish/m² The water level in tanks was maintained at 10 – 40 cm in depth, depending on the size of fish The system pump was switched on for 1 hour, twice a day
A partial water change was performed on the tanks after every four days of culture
Small snakehead were fed a diet that consisted mainly of earthworms, while larger fish were fed a diet that consisted of up to 70% trash fish To meet the system’s quantity requirements, earthworm cultures were initiated 1 month prior to stocking the system with fish
Garden (mainly vegetables) Pum
Manures for husbandry
or byproduct 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 20m2
Water circulated after treated
Earthworm shed (12 – 30 m2)
Trang 3Võ Văn Bình, Đào Văn Phú, Nguyễn Quang Chương, Mai Văn Tài, Ravi Fotedar & Jane Fewtrell
Economic analysis of the Improved VAC was
implemented by value estimation of input
(consisting of tanks depreciation, fingerlings,
feed), operation cost (pumping and labor
costs), and the value of output presented by
total production (from selling in markets, for
family or as gifts for relatives) multiplied by
the price at market
3 Results and discussions
3.1 Fish growth rate
In general, snakehead cultured in tanks in the
Improved VAC have grown fast, reaching 700
g/fish (approximately 40.5 cm in length) from
the initial size of 12 g (10 cm in length) after
about 5 months Fingerlings fed by ground
trash fish grew at the same rate as fingerlings
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 fish 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 These 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 Tinh 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 formal education This suggests that system knowledge and understanding could be an important factor in the success of the operation
3.2 Water quality in tanks and ponds
The results clearly show that the semi-bio filter
operated efficiently, resulting in lower levels
of NO2 and NH3 in tanks than those in ponds
(Figure 3) NO2was lower than 0.1 mg/l in all
demonstration sites; which is within the
acceptable range for normal growth rate of
aquatic species, including snakehead fish
In Quang Tri, for instances, the level of NH4 and NO2were low in tanks while in ponds they were sometimes higher than the acceptable limit The value of NH4 and NO2 fluctuated between 0.36 – 0.66 mg/l and 0.004 – 0.03 mg/l, respectively (Figure 3)
Fig 2 Growth rate of snakehead fish in tanks in the
Trieu Phong – Quang Tri Improved VAC
demonstrations
Trang 4Fig 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 possess an organ for breathing air
However, the concentration of NH4/NH3 and
NO2are critical issues to consider because they
are toxic to fish at low concentrations Both
trash fish and earthworms which were used to
feed the fish in these systems contain high protein levels which are quickly converted into
NH4/NH3 and NO2 within the system Therefore, levels of NH4/NH3 and NO2 must
be monitored and controlled
The parameters which are not content nitrogen 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
Temperature (°C) 25.6 23.4 32.1 27.2 33.7 27.4 33.0 27.0 32.1 28.3 31.0 27.9
dH – Hardness (mg/l) 6.8 6.5 8.0 7.0 7.8 6.8 7.3 9.7 7.6 8.6 8.3 8.2
These parameters were 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 and
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 that, due to the time restrictions of the project, the statistics on which the analyses were based were limited to a one year production cycle From the results obtained from the demonstrations, it can be seen that the Improved VAC system has potential to
Trang 5Võ Văn Bình, Đào Văn Phú, Nguyễn Quang Chương, Mai Văn Tài, Ravi Fotedar & Jane Fewtrell
financially benefit farmers using the integrated
system in Central coastal provinces
The results of analysis have shown that the
average return on investment (ROI) of
snakehead culture in tanks was high,
suggesting that the model can generate income
and benefit to famers The demonstration in Ha
Tinh gave a ROI index of 104% (Table 2)
while in Thanh Hoa and Quang Tri were
lower, at 71% and 41% respectively (Table 3)
The largest proportion of expenditure was for
feed, occupying 47.1%; followed by tanks
depreciation (10.3%) and cost of the
fingerlings (8.2%) Earthworms 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 Thạch Bàn – Thạch Hà – Hà Tĩnh
Tank depreciation (2 tanks x
20 m²)
1.000.000
Pumping cost (for circulation)
400.000
Fingerlings stocked (2000 fish)
800.000
Labor cost (for 4 months) 2.780.000
Table 3 Economic analyses of demonstrations in Thanh Hoa, Ha Tinh and Quang Tri provinces
3.4 Potential of snakehead culture in
tanks
3.4.1 Advantages and disadvantages
There are several advantages of culturing
snakehead in tanks:
1) When compared to pond aquaculture,
culture of fish in tanks requires a relatively
small area, thereby most households in the
middle coastal areas can easily include
aquaculture in their integrated farming
system
2) Trash fish, as feed for snakehead, is readily available in the coastal areas and it is relatively cheap Additionally, in the case of limited supply of trash fish (e.g weather disturbance such as a typhoon) earthworms from the Improved VAC can be used as an alternative feed
3) The culture conditions in tanks can be easily manipulated and therefore the alteration of cycles to suit individual situations and changes in the market is possible
4) Aquaculture in tanks requires relatively little water, thus, the operation cost for
Trang 6recirculation are reduced Also, in some
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
creating 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 relatively
advanced technology, so farmers must be
trained so that the system operates efficiently
and costs are kept to a minimum
3.4.2 Environmental aspect
a Within system
Snakehead are tolerant to low DO levels as
they possess air-breathing organs on sides of
the head (Munshi et al., 1994) However, with
high concentration of BOD and COD as found
in ponds, the fish will be susceptible to
Epizootic Ulcerative Syndrome (G N
Frerichs, 1993) A properly functioning
filtration system (i.e Improved VAC) will
address issues with dissolved organic material
in the water therefore, decreasing the
opportunity for disease to infect the culture
Iron levels are another concern for snakehead
in tanks Past experience and sampling has
shown that high iron levels in culture water
correlated with an increase on snakehead
mortality In addition, results suggest that the
growth rate of fish and FCR has a negative
correlation with increasing iron concentration
This was presented clearly in the Quang Tri
demonstration, where the iron concentration
was relatively high (> 3 mg/l)and the growth
performance and survival of the fish were low
when compared to those found in the systems
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 economic 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 can
be transported and kept very easily without mortality Despite this the economic efficiency
of the culture is very high More profit would
be possible if the farmers were to sell their produce directly to restaurants
The economic analysis of the culture of snakehead in tanks eliminated the notion that aquaculture is only possible in ponds Farmers now have evidence that they can include aquaculture into their integrated farming system with space of just 50 m²
4 Conclusions and recommendations
1 It has been shown that snakeheads have
a high growth rate in tanks, reaching to
700 g/fish after 5 months culture
2 From demonstrations, it can be concluded that the Improved VAC system is suitable for most situations in the central coastal area of Vietnam It would be beneficial for this model to be transferred to other farmers through the extension system
3 Water quality parameters tested during the culture indicated a suitable range for growth of aquatic animals, including for snakehead fish
Trang 7Võ Văn Bình, Đào Văn Phú, Nguyễn Quang Chương, Mai Văn Tài, Ravi Fotedar & Jane Fewtrell
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