Depending on the exact species, the water temperature needs to be kept at
around 85' for Tilapia to
thrive.
From The Perfect Fish http://www.aquanet.com/features/tilapia/perfectfish.htm
Since "everyone knows" that female tilapia grow slower than male tilapia, scientists came up with a method of treating all of the tilapia fingerlings with male hormones so those fish that would have been female now turn out to be male. Then all of the fish in the growing tanks or ponds will be male, and the average growth rate will be higher than it would have been with half males and half females.Now even the US government supports the use of reversal techniques by allowing all of the tilapia hatcheries who wish it to participate in what is known as an INAD. This basically means they have the right to put chemicals into the food of the fish that are not yet cleared as being safe, as long as they send results in to the government.
Almost every tilapia grower now uses hormone-treated fingerling tilapia. This basically reduces the time it takes to get the tilapia through the growing stage and hopefully allows for slightly higher profits from the sale of the fish since a farmer can grow more each year.
The truth is, however, that the only tilapia that grow faster if they are treated with methyl testosterone are the of the "pure line" species. These are produced by breeding, say, males of tilapia nilotica to female tilapia nilotica. If hybrids are produced using t. nilotica and T. aurea or T. mozambique and T. hornorum, any females that are produced will tend to grow as fast as the original male tilapia in the pure line species.

Scientific American article by C.F. Hickling, "The Cultivation of Tilapia,"
Studies 1 with some species of talipa show that "monoculture" (male only) ponds do not produce significantly higher yelds than "mixed" (male and female) ponds.
Also, while it may be that overpopulation will reduce the growth of the older fish, there are many non-chemical methods of reducing "recruitment" (the production of offspring) and some may even provide additional benifits. Fry numbers decline substantially at 10 ppt salinity. One method, which mimics nature, is the use of very low quantities of preditory fish to "pick off" excess fingerlings and sick adults. Possible preditors include:
While the production and consumtion of the fingerlings by the preditors does reduce the yeild of the crop fish, the preditors may also be used as food fish or to feed other producing stock such as Chickens.
Ocean Rich, Tilapia hatchery and farm in Thermal, California, ph (760)397-7302, fax (760)397-6101
Also:
See also:
From: http://www.da.gov.ph/tips/tilapia/freshwater.html
FARMING TIPS |
TILAPIA FRESHWATER FISHPOND
| Site Selection and Engineering | |
| Management of Freshwater Fishpond | |
| Pond Care and Maintenance | |
| Harvesting and Marketing |
Site Selection and
Engineering
The
success of freshwater fishpond farming depends on the selection of ideal
fishpon site, proper planning and layout design, proper construction and
appropriate pond management.
Considering the expenses involved in pond
construction, freshwater fishponds smaller than half a hectare are not
commercially viable. This technoguide is designed for freshwater fishponds
with an area of one-half hectare or more.
Site Selection
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 fishponds. 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.
Topography. Choose flat terrains for easier excavation and levelling.
If the topography is to 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.
Designing and Planning the Layout
In designing and planning the layout of freshwater fishponds, 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 pons 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
Preparation of Program of Work and
Schedule of Development
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.
|
|
requiremet (8 hr/day) |
(days) |
|
| Clearing/marking & levelling of dikes |
|
|
|
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 |
|
|
|
|
Construction of Pond System
Plan fishpond construction carefully and systematically. The system of pond constructioin is based on the prepared program and schedul of development.
|
|
|||||
|
|
|
|
|
|
|
| 1. Clearing/marking path & levelling |
--------- | |||||
| 2. Earthwork: a. Construction of dikes b. Construction of canals c. Levelling |
---------- ----------- |
|||||
| 3. Construction and installation
of gates and pipes a. Construction b. Installation |
------------- ------------- |
|||||
| 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, mechanicaly 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.
Construction and Installation of Water Control Structures
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 fishponds, 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.
|
|
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.
Pond bottom levelling
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.
Management of Freshwater Fishponds
Pond preparation
Prepare the ponds a month before stocking fish in the following manner:
Draining and
drying. Drain and dry the pond completely.
Dry for about a week or more, depending upon the weather, until the bottom
cracks or harden sufficiently to support a man on his feet without sinking
more than 1 cm.
Make sure the pond soil is dried everytime
the pond is harvested.Periodic drying stabilize soil colloids and oxidizes
organic matters that encourage the growth of natural fish foods. Draining
and drying eradicate competitor fishes and predators, and kill disease-causing
organisms.
Cultivation of pond
bottom. Till or cultivate the pond bottom
as soon as it is drained. Do this by stirring or cultivating with a shovel
or a rake for small ponds. For large pons, use a rotavator.
Cultivation makes sub-surface nutrients available
at the surface for the growth of fish food in the pond, eradicate burrowing
predators like mudfish and eliminate undesirable pond weeds like
"aragan."
Levelling. Level the pond bottom after this is cultivated. Levelling makes the pond bottom slope gradually from its farthest end down towards the drainage structures - the deepest portion of the pond.
Repairing gates and screens. Check all gates and pipes for broken slabs and other parts. Repair screens to prevent predators and pests from entering the pond system. Clean to remove debris which may cause clogging.
Repairing dikes. Check all dikes for leakages and seepages. All dikes must be water-tight. Put a puddle trench excavated about 30 cm wide and 50 cm deep or more along the dike. Build this at the center of dike towards one side, or dig two puddle trenches at both sides of pubbled trench long enough to cover the entire seepage and sufficiently deep to go beyond the general level of the pond floor. Fill the trench with new mud or soil. Allow the soil to settle well to give a firm line of earth.
Pests, Competition and Predator Control
Fish production in ponds is commonly affected by some pests and predators. Predators are organisms which prey on the cultured fish. Animals that compete for food or space are called competitors.
a. Piscivorous or predatory fish and other competitors
Catfish (hito), mudfish (dalag) and gourami may enter ponds during floods or when accidentally stocked with the cultured fish. These predators devour fry and fingerlings during or after stocking. To avoid them, drain the pond totally after harvest or before stocking.
Mudfish which tends to burrow into the mud, can be totally eliminated by using tobacco dust at the rate of 500 kg/ha.
Screen water gates and outlets properly to prevent entry of unwanted fishes. Check fingerlings properly for any possible contamination by predatory fish prior to stocking. Competitors are associated with predators. Both compete with the stocked fish for space and food.b. Birds
Herons, kingfishers and other birds must be prevented from frequenting the ponds. They devour fish and fingerlings and are also carriers of parasites. Ponds constructed without shallow areas are not attractive to birds.
c. Snakes
Snakes prey on small fish. Always keep banks and dikes clean to prevent snakes from harboring in the ponds.d. Frogs
Frogs eat fry and fingerlings. Tadpoles also compete with the fish for space and oxygen. Frogs are seldom found in well-fertilized and well-stocked ponds. Their population can be controlled by removing their egg sacks from the pond water.
Soil Conditioning
Soil acidity limits
the production of natural fish food by decreasing the amount of plant nutrients
and, in some extreme cases, kill fish. In cases where soil pH is below 7.0,
it is important to control acidity to ensure high fish production.
Analyze pond soil at least once a year to determine
its exact pH value. Soil analysis is especially recommended for newly constructed
fishponds as basis for proper soil conditioning. Refer to Appendix D for
proper collection of soil sample.
Methods of controlling and correcting acidity
Procedure in lime application
Broadcast or spread the needed lime over the drained but moist pond bottom. Mix the lime, thoroughly with the soil to attain maximum effectiveness. Allow one week to lapse before applying phosphate fertilizer.
Fertilizer Application
Applying fertilizer in ponds to supply the nutrients needed for plant growth is a fundamental part of fishpond management. Fish production per unit area can be increased as much as five-fold by proper application of fertilizer. Fertilizers are classified into two groups:
Organic Fertilizer.
The nutrients and organic matter content
of manure increase the water holding capacity of the soil, decrease the rate
of evaporation and increase enzymatic activity, all of which increase fertility
and yield. Animal manures contain the major nutrient components such as nitrogen
(N), phosphorous (P), and potassium (K), in addition to such trace elements
as calcium (Ca), copper Cu) iron (Fe) and magnesium (Mg). Phosphorous comes
mainly from feces except from swine manure which has more nitrogen and potassium.
Animals fed with roughage ration excrete more potassium than those fed with
high concentrate rations.
The chemical composition of manure also varies
depending upon the animals, nature and amount of manure and the handling
and storage of the manure before use. The most common organic fertilizer
used in fishponds are chicken dung, cattle manure and swine manure. Chicken
manure may be utilized as fish feeds and at the same time helps create a
soft mulch bottom to make a habitat for other food organisms. Compost, rice
bran, and sewage may also be used.
Inorganic Fertilizer. These are chemical fertilizers containing concentrated amount of at least one of the three major plant nutrients: nitrogen, phosphorous, and potassium. The common fertilizers used in fishponds are Super phosphate (0-20-0), Monoammonium phosphate (16-20-0), and Diammonium phosphate (18-45-0).
Techniques in Fertilizer Application
Plankton production
Plankton is a collective
term for all the small suspended organisms that passively drift and float
in the water. Most planktonic organisms are microscopic and consist of
phytoplankton (very small plants) and zooplankton (very small animals).
Tilapia consumes plankton as food. Plankton
is responsible for producing greater fish weight than any other type of natural
food raised in ponds.
Procedure in Growing Plankton:
Publications | Site Map | Links | Contact Us HOME |
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
James Newton replies: In the first instance, this refers to the initial construction of a dyke. Basically, loose organic material should be cleared away along what will become the centerline of the dyke at the base so that the dyke can "seal" to the underlying water-tight soil. In the second instance, this refers to repair of an existing dyke which is leaking. It is placed along side the dyke to increase the area that the repaired dyke is in contact with the underlying soil.+
Questions:
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