Aquaculture Learning Module G10

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Module 4 Fishpond Construction
Content Standards Performance Standards
The learner demonstrates
understanding of the underlying
concepts and principles in
constructing a fishpond.
The learner independently constructs
a fishpond.
Lesson 1. Construct a Fishpond
In the previous modules, you have learned the importance of accurate
layouting of the fishpond as well as the various criteria that have to be
considered in selecting a site for fishpond construction.
This module will provide information about constructing a fishpond. It
will cover the different activities involved in fishpond construction, starting
from clearing the area, installation of water control structures to earthwork.
At the end of the lesson, you are expected to:
1. prepare construction materials and manpower.
2. layout markers and strings based on accessories specifications.
3. construct different pond compartments based on specifications.
4. properly install accessories such as gates and pipes based on
specification.
Introduction
Specific Objectives

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Directions: Analyze the following statements below. In your test notebook,
write;
A – if statement A is true and statement B is false.
B – if statement A is false and statement B is true.
C – if both statements are true.
D – if both statements are false.
1. A. The main gate is usually situated at the corner of the fishpond.
B. The floor elevation of the main gate must be 0.3 meter higher than the
zero datum.
2. A. The ideal opening of the main gate for a 10 – 15 hectare fishpond is
1.0 meter.
B. For fishponds more than 15 hectares, the gate requires a multiple
opening.
2. A. The floor elevation of the gate should be lower than the lowest pond
bottom.
B. The floor of the main gate must be exposed during the lowest tide.
3. A. The dikes are hexagonal in cross-section.
B. The dikes must be of adequate size and shape to hold water as well
as to prevent seepage.
5. A. The minimum recommended width for dikes less than 3.0 meters
high is 2.4 meters.
B. For dikes used as a roadway, a width of at least 4.0 meters is
specified.
6. A. For dikes constructed lower than 4.26 meters, it should have a side
slope of 2:1.
B. For dikes constructed above 4.26 meters, it should have a side slope
of 1:1.
Pre-assessment

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7. A. The best time to construct the main gate is during neap tide.
B. All the materials needed must be prepared prior to the construction of
the main gate.
8. A. Avoid planting creeping grasses on the dike to prevent erosion.
B. Mangrove trees give the best protection to the main dike from
erosion.
9. A. Frequent inspection of the dike must be established.
B. The dike must be checked especially after the typhoon.
10. A. Leakage and seepage must be repaired and patched to avoid
erosion of dikes.
B. Trees and bushes should be allowed to grow on the dikes.
Development of a New Area
When all the requirements needed are at hand, fishpond construction
starts as planned. The system of farm construction will be based on the
prepared program and schedule of development. In cases where capital is
limited, partial construction can be practiced. That is, by developing a portion
of an area and the remaining parts or area shall be constructed or developed
using the income from the constructed fishpond.
Clearing the Area
 Underbrushing – is cutting of grasses, bushes, vines, shrubs and small
trees manually. The work should commence when the foundation of
the main dike and the main gate should have been established.
 Withering – is killing the trees by filling up the pond with water.

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 Falling – is cutting down of big trees left after underbrushing. The
falling operation should commence when the bark of the trees begin to
peel before the leaves and branches fall.
 Burning – is usually carried out when the dead trees have become dry.
 Uprooting of stumps and root system – is completely removing of tree
stumps and root system embedded in the soil.
Water Control Structures
1. Main Gate. The main gate links the pond system to the source of water. It
regulates the exchange of water between the pond system and the tidal
stream or sea. It should be made of concrete for effective control and
durability. The main gate is usually situated at the central side of the
proposed fishpond facing the source of water. Below are some information
needed in the design of the main gate:
 The floor elevation of the main gate should be lower than the lowest
pond bottom elevation desired. It should also be lower than extreme
low tides. The preferred elevation is 0.30 m lower than the zero datum.
 The height of the main gate depends on the top elevation of the main
dike which is dependent on tidal fluctuation, flood, and other factors in
the area.
 The opening of the main gate depends on how large is the area to be
flooded. Experience tells us that a 1.0 m opening of the main concrete
gate will flood a 10 -15 hectare pond system after two to three
successive high tides. Fishponds of more than 15 hectares will require
a multiple opening gate. Each opening should not exceed 1.2 m wide
for easy manipulation of slabs and screens.

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Parts of a Main Gate (Figure 20, See page 53)
a. Floor. The floor serves as the foundation of the structure and its
elevation is lower than the pond bottom elevation. The floor of the main
gate must not be exposed even during extreme low tides.
b. Apron. The apron generally rests on the foundation piles which are
made of seasoned bamboo driven at 0.3 m intervals into the soft soil
with the butt end up. The apron serves as protection against scouring
and seepage of water at the gate’s sides.
c. Cut-off. Walls are provided at both ends of the gate floor to prevent
seepage and undercutting of water over the gate’s foundation. They
extend down to the soil at a minimum depth of 0.60 m and are an
integral part of the gate’s foundation. Wooden sheet piles may be used
as cut-off wall.
d. Side of breast wall side walls. Define the sluiceway in addition to their
being retaining walls for the dike fill. Grooves or double cleats for
flashboards and screens are built on these walls. The top of these
walls are as high as the top of the dike.
e. Wing walls. These provide the transition from the sluiceway into the
main canal in addition to retaining the earth at both sides of the gate.
This transition improves the hydraulics of water flow by controling the
velocities of flow from one bed to another.
f. Bridge (or catwalk). This is a reinforced concrete slab or thick wooden
planks that span the side walls. At least two catwalks are provided,
located at regular intervals near the flashboard grooves.
g. Flashboard slabs or flashboards. Generally wooden pieces with a size
of 1.5 inch x 10 inches inserted into grooves or double cleats to control
the amount of water flowing through the gate.
h. Screens. Usually made of bamboo strips or fine polyethylene mesh
attached to a wooden rectangular frame that fits into the grooves. The

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screens prevent the escape of the cultured fish and the entry of
predators into the pond.
i. Pillars in wooden gates. Vertical supports where wooden walls are
nailed. They are placed at regular intervals to form a frame work.
j. Braces in wooden gates. These wooden frames hold or fasten two or
more pillars together or in place. They control the steady opening of a
gate.
2. Secondary and Tertiary gates (Figure 21, see page 54). Secondary and
tertiary gates control water to and from the main canal and into the pond.
These structures are usually made of wood and can be treated with coal
tar for durability. Secondary and tertiary gates are usually located centrally
at the shorter side of the compartment.
3. Dikes. It is a system of portioning and positioning on area for water control
and stock separation and distribution. They are made of soil materials
found in the area. Dikes are trapezoidal in cross- section. The side slopes
and the height are proportionally designed according to the soil material
used. They must be of adequate size and shape to hold the water as well
as to prevent seepage.
a. Height above the waterline. The top of the dike should extend
sufficiently above the waterline to give a safe margin against
overtopping at high tide and flood, and such allowance should include
wind-driven wave action. The designed height of a perimeter dike
normally has a freeboard, after shrinkage and settlement of 0.6 to 1.0m
above maximum flood water level observed in the locality for past 10 to
15 years. Freeboard for secondary and tertiary dikes is usually 0.30
meter.

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b. Top width. For an earth dike, the minimum recommended width for
dikes less than 3.0 m high is 2.4 m. For dikes used as roadway, a
width of at least 4.0 meter is specified. This width provides vehicular
space for access to ponds which should be at least 3.5 m, but
preferably 4.0 meter.
c. Side slope. The side slope (ratio of horizontal to vertical) is a function of
the type of soil used. The side of the dike inside the pond which is
constantly with water saturated is generally flattened than the outer
side which is always dry. If both sides are saturated, both side slopes
are the same.
Fishpond dikes constructed lower than 4.26 m should have a slope
of 1:1. Dikes constructed above 4.26 m should adopt a 2:1 slope.
d. Design height
1. The height of a main dike is calculated using the following formula:
Hm = ( HAT – GS ) + MF + FB
1 - %S
Where:
Hm = Height of the Main Dike
HAT = Highest Astronomical Tide
GS = Elevation of the Ground Surface
MF = Maximum Flood Level
FB = Allowance for Freeboard
%S = Percent Shrinkage and Settlement

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2. The height of a secondary dike is calculated using the following formula:
HS = ( HST – GS ) + MR + FB
1 - %S
Where:
HS = Height of the secondary dike
HST = Highest Spring Tide in the Locality
GS = Elevation of the Ground Surface
MR = Maximum Rainfall Within 24 hrs.
FB = Allowance for Freeboard
%S = Percent Shrinkage and Settlement
3. The height of a tertiary dike is calculated using the following formula:
Ht = ( DWL – GS ) + MR + FB
1 - %S
Where:
Ht = Height of the Tertiary dike
DWL = Desired Water Level
GS = Elevation of the Ground Surface
MR = Maximum Rainfall within 24 hrs
FB = Allowance for Freeboard
%S = Percent Shrinkage and Settlement
Dpb = Desired Pond Bottom Elevation
Dwd = Desired Water Depth

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Gate Construction and Installation
1. Main concrete gate
The main gate location depends on the layout of the fishpond. Usually,
it is constructed at the central side of the proposed fishpond facing the source
of water.
The main gate is constructed at the same time that the perimeter dike
is constructed to allow the curing of concrete while the main dike is
completed. The best time for construction is during neap tides or “ayaay”,
preferably during the months of February and March. Construction should be
completed before the spring tide comes. All the materials needed should
already be in the area before the construction of the gate is started.
Prior to construction, observe the tidal level in the place where the
main gate is to be constructed. To calculate the elevation of the ground
surface based on the height of the tide observed, set a tide pole and
determine the highest mark the tide has reached for the day. If no tide pole is
available, any permanent structure such as a tree can be used. Locate in the
tide table or tide calendar the time and date the high tide occurred and note
its height, and apply correction to the measurement. This height of tide is
reckoned from the Mean Lowest Low Water (MLLW). From this data, you can
approximate the elevation of the existing ground surface by adding the
differences in elevation (G) to the elevation of the tide observed (T).

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The elevation of the ground surface could also be determined
based on pre established bench mark, if it is available.
After conducting tidal observation, gate construction can begin. Below
are the procedures in constructing a concrete main gate:
1. Measure the area of the proposed concrete gate. Give a space
allowance of about 1-2 meters around for movement as the
markers are placed.
2. Enclose the markers with a temporary dike. Make the temporary
dike high and big enough to withstand the pressure of the incoming
tide. Pump or bail out the water inside the temporary dike.
3. Excavate the enclosed portion to a 0.6 meter deep. Remove the
stumps, roots and soft soil if there are any. Excavation should
include the portion where toes of the gate will be constructed.
4. Drive a 3 m long bamboo pole/culm or wooden posts into the
ground over the entire area of the gate at 1 m intervals. Leave 5 cm
of the piles exposed. Continue removing the soft and displaced soil
Height of tide
G
T River Bed
Ground Level
Ground
Elevation = T + G
MLLW
Figure 34. Calculation of Ground Level from Tide Observations

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as a result of the driving. Drive shorter (one to two meters) piling at
30cm intervals. The driven bamboo pole/culm should be levelled.
5. Insert boulders about 20 cm thick between the piles to form a floor.
Spread the gravel to level and cover the boulders, then compact
the filling materials, leave 5 cms of the bamboo piles exposed.
These piles should be embedded in the concrete mixture for a
stronger foundation.
6. Construct the form for the flooring including the toes. Place the
reinforcement bar and tie with number 16 wire. Check the elevation
of the flooring to be sure it is still within the desired elevation.
7. Install vertical and horizontal reinforcement bars for sidewalls,
wings and collars. Place the reinforcement bars for bridges and tie
them one by one. While installing the reinforcement bars, prepare
forms for the walls, wing, etc.
8. Set the forms for the walls, wings, collars and bridges. Properly
reinforce all the forms with wood so that it can withstand the
pressure of the concrete mixture. Fix the reinforcement bars at the
center of the forms. Pump the water out if there is any. Continue
pumping if necessary. Check if everything is in place and properly
fixed;
9. Prepare a class A concrete mixture (1:2:4) and pour it in the form
continuously until completed. While pouring the mixture, somebody
should compact the concrete with the use of a long stick to prevent
a hollow or void from forming and at the same time move large
stones to the middle of the form in order to insure a smooth finish
when the forms are removed. Prevent salt water from coming in
contact with the concrete mixture while it is still wet;
10. Allow concrete to harden for about 2-4 days, then remove the
forms. Apply finishing touches, especially at portions of the gate not
properly compacted;

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11. Sprinkle freshwater on the curing concrete every day for two weeks
and;
12. Remove the temporary dike after 30 days. Condition the gate by
letting tidal water in and out of the pond.
2. Wooden Gates
Secondary and tertiary gates are usually made of wood to reduce
construction cost. Like the main gate, secondary and tertiary gates are
constructed simultaneously with the construction of partition dikes. Because it
is easier to construct, it may not be necessary to have a temporary dike
enclosure. Keep the pond dry by closing the main gate.
Procedure in Constructing and Installing a Wooden Gate
1. Buy selected lumber and dry it under a shed for at least 15 days.
2. While shed drying the lumber, set a temporary bench mark (BM) near the
site of the gate to be constructed. Determine the elevation of the BM either
by the transit and stadia method or by using a transparent hose filled with
water.
3. Smooth the sides and edges of the lumber by using a plane. Cut the
lumber according to specifications given in the design of the wooden gate.
4. Assemble the pillars and braces with bronze nails. Nail the floor and the
walls to the pillars and braces. Nail the other parts.
5. Mix coal tar with a small amount of cement. Paint the wooden gate with
the mixture with at least two coatings and let it dry under the heat of the
sun.
6. Excavate the site to the desired elevation. Check the elevation from a
temporary BM previously set for such purpose.
7. Install the gate at the excavated foundation. Check if the gate is properly
installed and in the proper direction.
8. Fill the sides of the wooden gate with a layer of mud blocks layer.
9. Condition the gate by allowing tidal water in and out of the pond.

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Earthwork
Dike Construction
Dike construction begins by clearing vegetation, stumps and debris.
The clearing should be about 2 - 4 meters wider than the base of the dike. For
a main dike, a puddle trench (“mitsa”) of about 50 cms wide by 50cm deep
should be dug in the cleared path. For secondary and tertiary dikes, it may
not be necessary to dig a puddle trench, but it is advisable to construct the
dike where the soil substratum is loose and root ridden. The portion of the
dike passing through rivers, creeks or low places, if there are any, should be
constructed first. If possible, blocks of mud used for diking should be dug near
the dike for ease of construction and lower cost. Sandy clay soil makes the
strongest diking material. Whereas sand and root-ridden soils are inferior,
thus, these should be avoided. When filling with mud, the dike should not be
raised at once to its desired height. It should be done in layers allowing each
layer to settle before another layer is laid. Diking may be done either
manually, by machine or both. It is very important to have a uniform dike
height. A ½ in. in diameter hose, 25meters long, can be used to measure
accurately the uniformity of dike height. The hose is first filled with water, one
end should be held at the first station and the other end should be held at the
next station. The levels of water at both ends of the hose should be the same.
Then mark the height of the next station. Station to station should have a
distance of 20 meters. The process is repeated until the last station has been
marked.

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Canal Construction
Canal construction is done at the same time as construction of
adjacent dikes. Markers should be staked before construction starts. These
markers will serve as guide during the excavation of canals. The canal slope
will be the same as the dike. The canal should have a grade sloping towards
the main gate and the bottom should be flat so that the flow of water will be
uniform.
Pond Bottom Levelling
Mechanical levelling is a cheaper and faster means of levelling a pond
bottom than manual levelling if the soil condition will support the equipment
used. Farm tractors or tillers with a back blade may be used. Manual levelling
is done by slicing the soil into cubes using digging blades. The cubes are
loaded onto a sliding board, a bamboo raft or flat boat. The pond bottom
should slope gently towards the gate when levelling is finished. The steps in
levelling pond bottoms are as follows:
1. Bring the water down to the desired pond bottom elevation and place a
wooden mark. Beside the mark, place another stick about 2 meters long
calibrated from 0 to 100cm to serve as levelling guide for cut- fill operation
as well as to indicate the depth of water inside the pond. Set the stick so
that the zero mark is level with the wooden mark. The zero mark is the
required elevation of the pond bottom.
2. Mark area of the pond above and below zero elevation marks, then
increase the depth of water inside the pond to 40 cm for the flatboat to
float.
3. Excavate at a portion of the pond marked above zero elevation. Transport
the excavated soil with a flatboat and unload it at portion of the pond
marked below zero elevation. One to two workers should be at the
receiving end to supervise the dumping of soil in the depth portions. The

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receiver is equipped with a meter stick and from time to time check the
elevation of the pond bottom by the sounding method. If the desired
elevation is attained the receiver transfers to another low area.
4. When all marked portions have been excavated, drain the water to the
zero mark. The remaining soil on the sides can be levelled using a spade.
5. The process is repeated until all lower portions are filled.
6. Excess soil materials are transported to other compartments having low
areas or are utilized as berm for the dike or to increase its height.
Protection, Repair and Maintenance
Creeping grasses should be planted on the top and slope of the dike
for protection from erosion as soon as the construction of dike is completed.
Grass can be maintained by fertilizing and minimizing foot traffic. “Dampalit” is
the most common grass that grows in brackish water ponds and can also be
planted over the dike. Carabao grasses may also be grown on the dikes.
Mangrove trees give the best protection to main dikes, especially if
salvage or buffer zones are required along the river or bay. Vegetation left
undisturbed in a wide belt indicate width of belt of mangrove counteracts the
destructive action of the waves. The salvage zone also serves as an
ecological balance in the area. Erosion of dikes inside a pond is controlled by
placing twigs along the side of the dike. The twigs also serve as protection for
natural fish food. Some fishpond operators construct broken dikes inside the
pond to break and minimize the wave action. Constructing of berm along the
foot of the dike also protects the dike from wave action.

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Dikes which are exposed to open water are at times subject to the
destructive action of waves. Protective measures to safeguard such dikes are
as follows:
a. Riprap. A foundation or sustaining walls of stones, concrete block or
concrete slabs hand placed compactly or irregularly on the dike slope
in order to prevent the scouring action of water. The provision for a
banquette on the seaside slope of the dike is an added protection, as
riprap placed on the banquette is prevented from slipping. The
banquette area is covered with coarse crushed stones with a thickness
of 0.10m to 0.20m before the riprap is placed. The crushed stone fill
form a bedding layer that prevents the erosion of the soil beneath the
riprap.
Stones used for riprap should be dense and hard enough to
withstand exposure to air and water. Rough angular stones are
preferred to smooth rounded stone as rounded stone does not
interlock or resist movement.
b. External Support. Failure due to rotational slipping is quite common in
dikes. This is due to lose sharing resistance of the soil when wet or
saturated as well as its corresponding increase in weight. The dike
slope is stabilized by providing external pile support at the toe or by the
application of heavy loading on the toe. The use of bamboo culms as
piles serves the purpose very well and the use of boulders provides the
external load.
Frequent and scheduled inspection of the dike must be
established as this provides early detection of erosion and allows time
for repair before major damage occurs. The dike must be checked
especially after storms. Leakages and seepages must be thoroughly
inspected as they are the possible causes of failure.

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Burrowing aquatic animals such as crabs can cause serious
damage to a dike. Traps or plastic sheets may be installed to eliminate
or prevent them from boring holes.
Harvesting of oysters, if they grow on the boulders placed at the
dike toe, must be prevented as the harvesting process causes the
rocks to be moved.
Trees and bushes should not be allowed to grow on the dike as
the roots loosen the dike soil.
The top of the dike should be filled with a suitable earth
material. Surface drainage must be done immediately so that no water
will percolate into the dike soil.
Direction: Make a diorama of a main gate and a perimeter dike using your
own dimension. Refer to Figure 28 and use recycled materials as much as
possible.
A. Diorama of a Concrete Main Gate
Materials:
 Card board/illustration board or match box
 Pencil, eraser, ruler
 Pair of scissors or cutter
 Glue
 Coloring materials (crayons, oil pastel coloring material, water color
or paint)
 Marker

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Procedure:
1. Layout the desired dimension of the main gate on an illustration board.
2. Decide on the thickness of the walls of the main gate, height and width.
Layout them on a card board using your pencil and ruler. If you are to
use a match box, its thickness, width and height will automatically be
the dimension of your main gate.
3. After preparing your desired layout, cut out the pieces using a cutter or
pair of scissors.
4. Assemble each piece/part following your desired dimension.
5. After putting all pieces/parts together, paint the diorama using your
coloring material
6. Label each part using your marker.
Figure 29. Sample Diorama of Concrete Main Gate
Front View
Side View

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B. Diorama of a Perimeter Dike
I. Materials:
 Card board/illustration board
 Pencil, eraser, ruler
 Pair of scissors or cutter
 Glue
 Coloring materials (Crayons, Oil pastel coloring material, water color
or paint)
 Marker
II. Procedure:
1. Layout the dimension of the perimeter dike on a card board. Follow the
recommended height, top width, slope, base, puddle trench and berm
of the dike.
2. Cut each piece using a pair of scissors or a cutter.
3. Assemble each part using the glue.
4. After putting all pieces/parts together, color your diorama using your
coloring materials.
5. Label each part using your marker.
Figure 30. Sample Diorama of Perimeter Dike
Front View Top View
Crown
Side Slope
Base
Puddle
trench
Berm

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1. How will you mobilize resources during the construction of a fishpond?
2. Why is it important to have a program of works prior to the construction
of the fishpond system?
3. What measures will you do to ensure the construction of the different
parts of a fishpond in accordance with the program of works and with a
high degree of accuracy and functionality.
Directions: Make a model of your fish farm. Apply the skills that you learned
from the previous modules/lessons. Figure 4 below will give you an idea on
how to do it. Use recycled materials as much as possible.
Figure 31. A model Obando School of Fisheries Fish Farm
Model
Brackish water Fishpond
Hatchery Tanks

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Directions. Analyze the following statements below. In your test notebook,
write;
A – if statement A is true and statement B is false.
B – if statement A is false and statement B is true.
C – if both statements are true.
D – if both statements are false.
1. A. The main gate is usually situated at the corner of the fishpond.
B. The floor elevation of the main gate must be 0.3 meter higher than the
zero datum.
2. B. The ideal opening of the main gate for a 10 – 15 hectare fishpond is
1.0 meter.
B. For fishponds more than 15 hectares, the gate requires a multiple
opening.
4. A. The floor elevation of the gate should be lower than the lowest pond
bottom.
B. The floor of the main gate must be exposed during the lowest tide.
5. A. The dikes are hexagonal in cross-section.
B. The dikes must be of adequate size and shape to hold water as well
as to prevent seepage.
5. A. The minimum recommended width for dikes less than 3.0 meters
high is 2.4 meters.
B. For dikes used as a roadway, a width of at least 4.0 meters is
specified.
6. A. For dikes constructed lower than 4.26 meters, it should have a side
slope of 2:1.
B. For dikes constructed above 4.26 meters, it should have a side slope
of 1:1.
Post Assessment

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7. A. The best time to construct the main gate is during neap tide.
B. All the materials needed must be prepared prior to the construction of
the main gate.
8. A. Avoid planting creeping grasses on the dike to prevent erosion.
B. Mangrove trees give the best protection to the main dike from
erosion.
9. A. Frequent inspection of the dike must be established.
B. The dike must be checked especially after the typhoon.
10. A. Leakage and seepage must be repaired and patched to avoid
erosion of dikes.
B. Trees and bushes should be allowed to grow on the dikes.
Banquette. Sidewalk
Berm. A narrow shelf, path, or ledge typically at the top or bottom of the
slope
Coal tar. A black, sticky, liquid made from coal that is used as a fuel and
used specially as industrial fuel and to make various products (such as soap)
Debris. The remains of something broken down or destroyed; an
accumulation of fragments of rocks
Elevation. The height of a place
Hydraulics. The flow or liquid in pipes, rivers, and channels
Neap tide. Tide of minimum range occurring at the first and third quarter of
the moon
Percolate. To pass slowly through something that has many small holes in it
Glossary

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Riprap. A layer of similar material on an embankment slope to prevent
erosion
Saturated. Full of moisture; made thoroughly wet
Seepage. An occurrence in which a liquid or gas flows or passes slowly
through small openings
Sluice. A device (such as a floodgate) used for controlling the flow of water
Spring tide. A tide of greater-than-average range around the times of new
moon and full moon
Tide. The regular upward and downward movement of the level of the ocean
that is caused by the pull of the Sun and the Moon on the Earth
Velocity. The rate of change of position along a straight line with respect to
time; the derivative of position with respect to time

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Coursepack:
Republic of the Philippines, Department of Education. Public Technical
Vocational High School. Competency- based learning material. Third Year:
Aquaculture NC II.
Toledo, C. (2009). AQUA203: Aquaculture engineering. Lecture manual.
Pangasinan State University, Binmaley Campus.
Website:
Meriam- Webster Online Dictionary. http://www.merriam-webster.com/
Other:
Department of Education. Bureau of Secondary Education. Technical
Vocational Unit. Competency-Based Curriculum Aquaculture NC II. 2012.
34p.
Resources