ENGINEERING INFORMATION

TYPES OF FISH PONDS

Executive mai Doya 14 AGRICULTURAL ENGINEERING 5:44 AM

There are basically two types of pond systems viz;<br />
i.    Earthen or natural type and<br />
ii.    Concrete type.<br />
We also have the plastic type, metal type, glass type, wooden type etc.<br />
<h2>
Earthen or natural type ponds</h2>
The location for earthen pond is limited to area where there is clay soil and underground water or a flowing stream. It is therefore sited in swampy area where clean fresh water is available.<br />
The pond is always a dug-out type to an average of 1.5m depth. The dugout soil is used to build dyke round the pond to prevent flooding during rainy season and the water of an earthen pond is normally 1.2m deep.<br />
<br />
    Earthen pond can be contour or a dugout pond. The former is constructed in the slope of a highland with clay soil and nearby stream, while the later is constructed in a flat swampy land which can either be dry or wet and water allowed to naturally flow from underground in the pond.<br />
<h3>
Advantages/Disadvantages of earthen pond</h3>
    Some of the advantages of this type of ponds are:<br />
i.    It is relatively cheaper to construct.<br />
ii.    It has large stocking capacity.<br />
iii.    Fish live in natural environment.<br />
iv.    Fish growth is rapid<br />
v.    High profit margin may be envisaged.<br />
<br />
<h4>
Disadvantages</h4>
i.    The major shortcoming of this type of pond is need for fencing and security guards.<br />
ii.    Flooding may occur if the dyke is not properly built during construction and if not controlled may lead to fish escape, pond water pollution, or even total collapse of the earthen pond.<br />
iii.    Sorting may be difficult in earthen pond.<br />
<br />
<h2>
Earthen pond based on water supply</h2>
    There are two major ponds based on water supply, viz:<br />
<h4>
Barrage pond</h4>
This type of pond is constructed along the main path of flow of stream or river water. Both up-stream and down-stream are barricaded with inlet and outlet respectively. The advantage of this pond is its low construction cost and sufficient amount of water all through the culture period.<br />
    The failure associated with this kind of pond is the likelihood of flooding during the rainy season and the whole pond system can be washed away including the stocks.<br />
<h4>
Diversion or Contour pond</h4>
This type of pond is constructed in the by-pass of a stream or river. A water supply channel is built for this purpose with sluice or inlet gate at the entrance to control the volume of water coming in or going out of the pond and also to the influx of extraneous materials. In this case, flood effect is minimal compared to barrage type.<br />
<br />
<h3>

Types of Diversion pond</h3>
<h4>
<b>Series pond</b></h4>
This ponds are built such that each pond derives its water supply from the other and also empty into another. This is the worst approach to pond design, hence it is not recommended, as whatever affects one would definitely affect the other.<br />
<h4>
Parallel pond</h4>
Ponds constructed this way are independent of one another in their sources of water supply and discharge. All activities relating to filling and drainage of water are limited to each pond respectively.<br />
    In this work, emphasis will be laid on the design of a parallel concrete fish pond.<br />
<br />
<h2>
Types of ponds based on usage</h2>
<h3>
 Holding pond: </h3>
This is used to hold fish temporally in readiness for either transportation or fattening for induced breeding purpose.<br />
<h3>
Spawning pond: </h3>
used to hold the set of fish intended for artificial propagation.<br />
<h3>
Segregation pond: </h3>
Used to hold fishes either of the same sex or the same species.<br />
<h3>
Nursery pond: </h3>
used to nurse the fry produced during induced breeding into fingerlings.<br />
<h3>
Grow out pond: </h3>
used to raise fingerlings to table size fish.<br />
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<h2>
Concrete as a material for fish pond construction</h2>
As the name implies, concrete ponds are constructed using cement, blocks and aggregate of suitable ratio. Concrete pond can be classified in three different ways viz: stagnant concrete pond , free flow concrete pond and water recirculatory concrete pond.<br />
<h3>
Stagnant concrete pond</h3>
In the stagnant concrete pond, water in the pond is seldom replaced. No water flow out channel is provided during construction. Water replacement is based on when it is polluted and a pumping machine is employed for the purpose. The pond is cheaper to construct with limitation in quantity of fish stocking capacity. A pond of 2m x 5m capacity may not stock more than 600 fish. Fish growth may not be fast as expected due to poor water condition. It could elongate to up to nine months to reach the desired table size of 1.0kg.<br />
<h3>
Free flow concrete pond</h3>
This type of pond is suitable for quick response grow-out fish and the scope of this work will be centred on this system of pond. The construction includes water flow-out channel. Water flow is regulated and continuous at stipulated period. This ensures water freshness and turbulent that makes the fish agile for improved feeding rate. A free flow concrete pond of 2mx5m capacity may stock between 1,000 and 1,800 fishes given space requirement of between 0.005m2 to 0.01m2 per adult catfish.<br />
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The major problem of the pond is that water wastage may be on the high side. This will be feasible where constant water supply is guaranteed.<br />
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<h3>
Water recirculatory concrete pond</h3>
The construction of this type of pond include complete water refining (filtration) system. The system involves high water efficiency. Water in storage tanks at elevated height flows freely into the pond. Waste water out of the pond is either stored in another chamber or passed directly through a bio-filter re-circulation and it is a continuous action. This type of pond is the most advanced in terms of water efficiency, stocking capacity, water quality and percentage of dissolved oxygen in the pond water among other attributes and derivable benefits but have a very high initial cost of construction and equipment benefits acquisition. Maintenance cost is also high. There will be need for clean out of the pond once a while to remove accumulated solid wastes from the bottom of the pond.<br />
<br />
Above all, derivable benefits out ways the initial capital cost in terms of stocking capacity, faster fish grow-out and water consumed will be less.<br />
<br />
<h2>
Importance of concrete fish pond</h2>
i.    Concrete fish ponds are usually constructed for the purpose of culturing fish were flowing streams of water or river is not available. Hence, concrete fish ponds afford us the opportunity of culturing fish around our homes and immediate surroundings such as school and college premises, office areas, industrial and commercial centres etc.<br />
ii.    It can be constructed purposely for storing live fish till needed. Such life fish must have reached table size (that is at leastz 400-500 grammes in weight) before storage.<br />
iii.    Concrete fish ponds are also useful for fingerlings production especially in the case of fish species which breed easily in captivity e.g. Tilapia species, clarias species.<br />
<br />
<h2>

Design of Artificial Fish Pond</h2>
    The most popular types of artificial fish ponds are wooden (vats) and the ones made with blocks and concrete mix.<br />
<h3>
Vats or wooden type of fish pond</h3>
    This is basically the use of wood for artificial fish pond construction. It is one of the most inexpensive materials but does require a coating to prevent rotting and seepage. Plywood of either 1.3 or 1.6cm thick is normally used. However, a 12ft x 3ft with a height of 1ft or 12ft x 3ft with a height of 2ft or 12ft x 4ft with a height of 2ft employed for the design and construction of vat is capable of housing 1500 fries, 800 fingerlings, and 350 table sized cat fish respectively. Structural members are fastened between the rings at approximately 30cm spacing for a 1m depth pond. Spacing of vertical members varies depending on water depth in the pond and the thickness of plywood, the further apart the vertical supports may be placed. Structural supports are also necessary across the pond bottom unless the pond is located on a solid foundation and not moved. The entire pond should be coated with epoxy or other non toxic sealer. Alternatively, by covering the interior surface with tarpaulin. Coating the exterior prevents slow deterioration of the wood from high humidity and splashed water. An exterior coating, but maximum pond life will be achieved by coating the exterior. The pond interior must have atleast one coat of sealing material and may be more (depending on the coating material used).<br />
<br />
Ponds up to atleast 1.25m deep and more than 2.5m long will need heavier top and bottom rings or supports across the centre of these rings. However, the design of epoxy-coated plywood ponds cannot be based solely on allowable stress. Strain must be minimized because many coating materials are highly brittle. Strain or flexure of the pond walls under load will crack many epoxy coatings. The resulting leaks often create a mess at best, and a fish killed due to lack of water at worst. Even if a leak does not develop, water will get into the plywood, causing rapid deterioration and eventually pond failure.<br />
<br />
<h3>
Block and concrete mix (Concrete fish pond)</h3>
<h4>
    Design and construction of concrete fish pond involve the following:</h4>
i.    Site selection<br />
Concrete fish pond can be sited in any open space near one’s immediate surrounding provided the space is free from shade, and effective security can be guaranteed.<br />
<br />
ii.    Excavation of concrete fish ponds<br />
In order to prevent rise in the temperature of water, especially in the lower part of the concrete fish pond, the lower 60cm (2ft) should be sunk in the ground. This implies that the whole area to be occupied by the concrete should be escavated to a depth of about 60cm before laying the foundation blocks.<br />
    Alternatively, the site may be excavated. In such a case, a thick layer of soil should be packed around the base of the concrete fish pond, covering its lower 60cm.<br />
iii.    Erection of the walls<br />
Unlike earthen ponds, the walls of a concrete fish ponds are usually built with concrete blocks. The concrete blocks used for the construction are usually reinforced (that is filled with concrete or sandcrete). This will strengthen the walls thereby enabling them to withstand the pressure of the water which the concrete fish pond will require.<br />
Also, as found necessary, pillars should be installed along the walls at suitable intervals to prevent cracking of the walls.<br />
iv.    Installation of water inlet, water outlet and overflow pipe.<br />
After the walls of the concrete fish pond have been erected the water inlet and outlet should be installed. It (concrete fish pond) has neither a monk or a spillway (unless the concrete fish pond is a large one). Instead, it has an overflow pipe for eliminating excess water in order to forestall overflowing which usually brings about loss of fish. For an overflow pipe to be effective in preventing overflowing of pond water, its size or diameter should be greater than that of the inlet pipe. The overflow pipe should be screened in order to prevent loss of fish.<br />
v.    Plastering:<br />
Both the inner and outer surfaces of the walls of concrete fish pond should be plastered with mortar to further strengthen the walls  and also prevent loss of pond water through leakage.<br />
vi.    The Floor<br />
The floor of concrete fish pond should be made of concrete in order to prevent loss of pond water through seepage. The floor should slope gently towards the water outlet in order to facilitate drainage of the pond water.

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