POND CONSTRUCTION

A fish pond is a confined body of water where fish are raised under controlled conditions. Fish can also be raised in plastics, fiber stars, and wooden rafts. This article is all about pond construction and how to choose the best option for your needs.

Generally, there are two main types of Ponds. This can either be an earthen pond or concrete pond.

FACTORS TO BE CONSIDERED IN POND CONSTRUCTION

1. Market: There should be a fish market near-by to allow for the high capacity of the sale of fish from pond harvests. The market requirement is the first requirement for locating any agriculture business especially a fish farm. This will further help address issues relating to the transportation of the fish to the market.

2. Nature of the soil:  The ideal soil for pond construction has to have enough clay content to hold water. Clay and silty clays are excellent soils for holding water because they stop water from seeping through[i]. Clay should make up at least 20-25% of the soil[ii]. The soil should be checked for residual chemicals from previous farm activities which could have an effect on fish health.

 3. Topography: Topography that allows for economical construction. It directly affects building costs and pond management. The pond should be constructed where enough water can be impounded with the least amount of earth fill. Areas with large shallow water should be avoided because they become too shallow to use during the dry season.

4. Water availability and quality: water could be obtained from boreholes, streams, or lakes. Gravity flow water is the cheapest and best source. The water must be unpolluted, uncontaminated. Borehole waters can be excellent but may be costly to pump and may require conditioning to remove carbon dioxide and improve oxygen content and temperature levels. Open waters from canals and streams may be polluted or be contaminated from runoff from farmlands or towns. Waters used in aquaculture need to be tested for quality e.g. water with alkalinities less than 30 ppm (CaCO₃) will require liming to bring up pH levels close to neutrality (7.0) for best fish production

TYPES OF POND

1. EARTHEN POND

This involves digging the soil usually clay (25 % clay) to a depth ranging from 0.5- 1.0 m at the shallow end and 1.5- 2.0 m at the drain end to raise fish. A pond can be of any shape as long as it is well constructed. However rectangular or square shapes are considered the best. This is usually practicable in a swamping environment. This takes away from the problem of water maintenance as there is a natural flow in and out of water in the pond.

Steps Involved in Earthen Pond Construction

The following steps are required:

• Clearing of the proposed site

• Setting‐out which involves pegging and lining with the rope

• Mark‐out the areas inlet and outlet

• Topsoil removal and storage

• Construction of embankment

• Construction of inlet drainage pipes/ water control structures

• Construction of screen at both inlet and outlet.

Excavated Pond Construction

An excavated pond is often built on level terrain and its depth is achieved solely by excavation.  An excavated pond is relatively safe from flood damage, is low maintenance, and can be built to expose a minimum water surface area in relation to volume. This is beneficial in areas of high evaporation losses and a limited amount of water supply. Ponds should have gentle slopes on dikes as depicted in the Figure below

Embankment Pond Construction

This type of pond is built by creating an embankment or dam used to impound water and is usually constructed in a valley or on gently sloping land. It is not recommended to build an embankment pond on greater than a 4% slope. Less excavation may be needed to build this type of pond.

2. CONCRETE POND

Here, 4-5 coaches of blocks are used to construct the pond above the ground level, using cement, sand, and gravel in ratio 1:2:4 respectively with water. The pond floor should be well paved to a thickness of between 7.5cm- 10cm. The wall should be plastered to a thickness of 5cm. Water tap should be well connected to allow free flow in and out of water. This particular type has the advantage of enabling you to monitor the hygiene of your fishes.

3. PLASTIC POND

Pond construction is expensive and this has led many entrants to fish farming in Nigeria to build concrete tanks or to buy plastic tanks as production units. These are smaller units but are believed to be easier to manage as production units. Nigerian farmers have limited land and tank fish farming adapts well to their conditions than larger, more expensive earthen ponds. It is also noted that the quantity of fish harvested from such smaller production units is more easily marketed than harvests from large fish ponds. There are different shapes and sizes of tanks used, as shown below:

For more information or help in constructing your fish pond CONTACT US senceagric@senceworld.com

REFERENCES

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