From: http://www.da.gov.ph/tips/tilapia/freshwater.html
The success of freshwater fishpond farming depends on the selection of ideal
fish pond site, proper planning and layout design, proper construction and
appropriate pond management.
Considering the expenses involved in pond construction, freshwater fish ponds
smaller than half a hectare are not commercially viable. This technoguide
is designed for freshwater fish ponds with an area of one-half hectare or
more.
Water supply. Water supply is the foremost factor to consider in selecting a fishpond site. The site must be accessible to adequate water supply throughout the year and free from pesticide contamination and pollution. Sources of water can be a surface runoff, stream, creek or irrigation.
Soil characteristics. Clay, clay loam, and sandy loam soils with deposits of organic matter of about 16% are best for fish ponds. Hard mud of the above types are preferable to the soft and very loose kind. Avoid sandy, rocky or stony soils because these do not retain water in the ponds. Some of the methods to determine if the soil will hold water are:
Avoid areas with thick deposits of organic debris since these are poor materials for diking. Consider also the pH value of the soil in selecting the site. The most desirable range of pH is 7-9.
For liner tanks/ponds: liner must be installed so there are no folds that Tilapia can bite to scrape algae off liner. Biting/scraping can lead to liner failure and loss of water and fish.
Topography. Choose flat terrains for easier
excavation and levelling. If the topography is too undulating, the construction
costs increase greatly and excavation work removes the fertile portion of
the pond bottom. Avoid sites that are frequently flooded.
Other factors to consider are availability of quality fingerlings and cheap
skilled labor, accessibility to market and peace and order condition.
In designing and planning the layout of freshwater fish ponds, give careful consideration to the following:
Pond compartments. There are three compartments
in a complete freshwater fishpond system namely: nursery pond, brood pond
and production or rearing pond. The nursery and brood ponds may comprise
10% of the total area, and 90% for the production pond.
The pond may be rectangular or irregular in shape. The size of the compartment
is governed by the topography of the land. This may vary from less than one
to two hectares for good management. Smaller pond units require greater
construction and maintenance cost.
Water supply. Provide each compartment with
an individual water supply system and drainage outlet. Provide also a mechanical
emergency spillway for the flow of excess water from ordinary rain and to
maintain desired water level in the pond.
Drainage. Construct the pond to facilitate easy drainage when harvesting
fish stock and proper cleaning of the pond bottom.
Elevation. Construct the pond one meter or more lower than the source
of water supply but slightly higher than the drainage area to obtain at least
an average water depth of one meter for maximum production.
Wind direction. Wind plays a role in fishpond design. Strong wind generates wave action that destroys the sides of the dikes. To minimize this, position the longer pond dimensions parallel to the direction of the prevailing wind to lessen the side length of the dike exposed to wave action.
Protection from flood. If the fish pond site is prone to flooding, construct a diversion canal along the perimeter dike to divert runoff water during heavy downpour. Construct a larger and higher perimeter dike to prevent inflow of water.
Designing dikes. Construct dikes with trapezoidal cross section with the top width, the side slopes and the height proportionally designed according to the soil material used. The following are guidelines in designing the dikes:
Relationship among the top width, bottom width and height of dikes with a given side slope
Height
Top width of crown (m)
Bottom, with in m. at given side slope
1:1 ratio
1.5:1 ratio
2:1 ratio
1.5
2
3
4
1
1
2
3
4
5
8
11
5
7
11
15
7
9
14
19
Project programming is undertaken to determine how
and when a project will start and be completed within a given period based
on daily output, or by determining the number of days a piece of work can
be finished based on the available labor in the area.
The program of work is the basis of implementation of the
project. Evaluate and calculate each item realistically so that each job
is properly developed and economically done.
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requirement (8 hr/day) |
(days) |
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Clearing/marking & levelling of dikes |
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plastic hose (1 cm diameter, 50 cm long), meter stick |
Earthwork a. construction of dikes b. construction of canals c. Levelling |
contract labor contract labor contract labor |
20 laborers 10 laborers 5 laborers |
45 20 10 |
digging blades, tractor, rotavator |
Construction &
installation of gates & pipes a. construction b. Installation |
daily daily |
5 laborers 5 laborers |
10 10 |
Carpentry/tools |
Finishing touches |
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Plan fishpond construction carefully and systematically. The system of pond construction is based on the prepared program and schedule of development.
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1. Clearing/marking path & levelling |
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2. Earthwork: a. Construction of dikes b. Construction of canals c. Levelling |
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3. Construction and installation
of gates and pipes a. Construction b. Installation |
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4. Finishing touches | -------------- |
Clearing the area. Clear the entire area of all grasses, roots and stumps. Burn these thoroughly. Strip surface to an adequate depth to remove all objectionable or organic matters.
Dike construction. Clear the dike site of
vegetation, slumps and debris. Clear the strip 2-4 m wider than the base
of the dike. For sites with decaying matters, construct a puddle trench at
the center of the path of the dike. Excavate 0.5 m wide by 0.5 m deep trench
filled with clay soil to prevent excessive seepage on the finished dike.
Dig blocks of mud for construction of dike at least one meter from its base.
Allow each layer to settle firmly before adding another layer until the desired
height is attained. Construct dikes either manually, mechanically or both.
It is very important to have a uniform dike height. To do this, get a 50
m long transparent plastic hose. Fill the hose with water. Hold one end of
the hose at the first station and the other end at the next 40 m away (figure
6). If the water level at both ends are the same, the dike is level. Repeat
the process until the last station has been marked.
Canal construction. Construct the canals simultaneously as the adjacent dikes. Stake markers to serve as guide during the excavation of canals. Slope the canal gently towards the drainage gate of pipe to keep the flow of water sluggish and to avoid excessive erosion.
Water inlet or outlet structures are usually made
of wood or concrete gates, galvanized iron sheets or reinforced concrete
pipes.
Place 3 pairs of grooves on each side of wooden or concrete gates extending
to the top of the dike where they are installed. The middle pair of grooves
allows the removable slabs to regulate the flow of water. The first and third
pairs enable the screens to prevent the escape of cultured fish. These screens
may either be of bamboo splits or nylon attached to a wooden frame.
In freshwater fish ponds, galvanized iron pipes or reinforced concrete pipes
are often used instead of concrete wooden gates. The following is a guide
in determining the proper pipe diameter to be installed.
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6 12 |
Can drain the same in three days Can drain the same in one day |
Source: Site Selection, Design/Layout and Construction
of Fishpond by C.R. dela Cruz
With proper scheduling of draining time, it is adequate
to use 4 to 6 inch pipe for one hectare pond and 6 to 11 inch pipe for larger
ponds.
Construct water supply and drainage system simultaneously with the
dikes.
Mechanical levelling is
cheaper and faster than manual levelling if the pond bottom can support the
equipment used. Use farm tractors or tillers with a back blade. The carabao
and the harrow may be used in small ponds. The pond bottom should slope gently
towards the drainage gate to facilitate complete drainage.
After levelling the pond, plant creeping grasses at the dikes to prevent
erosion. Plant bananas at the outside slope of the perimeter dike to serve
as wind breakers. Do not plant trees along the dikes because the roots will
cause leakage and seepage.
Next: Tilapia Pond Preperation and Management
Comments:
Very useful and instructive but the issue about the "puddle trenches" location is confusing. In one place it places it in the middle of the wall (base?)due to organic matter in the floor and then more towards a side, etc,.
Is there a site that would deal more specifically with earthen walls ponds or a book that wouldn´t cost an arm and a leg.
Thank you
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