Before beginning the construction of a new fish pond, carefully consider the design. A properly designed and constructed pond will be easily managed and will last longer. This saves extra work and brings greater profit.
Design considerations to address
- The source of water used to fill the pond
- How water will be brought to the pond
- The type of soil available for building the pond
- The size, shape and depth of the pond
- The slope of the pond bottom l The height, width and slope of the dykes
- The type of drainage system that will be used
- The layout of ponds used for different sizes of fish
Other issues to consider
- What type of pond do you wish to build?
- What type of fish can be grown here? Remember if you wish to be a fingerling producer (fish at six weeks), you require small ponds. A food fish producer requires relatively large ponds.
- Ponds should be designed based on the type of soil present and the intended culture practices.
- The water source must be able to keep the pond full throughout the culture period.
- Relatively shallow ponds are productive, but the shallow end should be at least 0.5m deep to avoid invasion by weeds.
- It is always desirable to place screens on pond inlets and outlets to keep out predators, insects and unwanted fish, and to retain the cultured fish.
- Every pond should be drainable.
- Every pond should have an independent controlled inlet and outlet.
- Excavation of a core trench should be done where soils are less suitable. l Perimeter and feeder roads are required to provide for movement of machines during construction and at harvest.
- If you plan to drive on the dykes, build them at least three metres wide on top, and wider at the base.
- Soil used to build dykes should always be compacted in layers.
Land area for ponds
You need to establish that the land is relatively levelled. Steeply sloped land is not generally suitable for building ponds. A slope of about 1% is considered ideal.
The area should not be prone to flooding. Study weather records for the area, ask local residents about flooding in recent years, and look for actual evidence that flooding has occurred.
The area should not be subject to pollution in run-off from adjacent land.
Find out who owns adjacent and uphill land, how they use the land, and what chemicals (including fertilisers and pesticides) they use.
If possible, the land must be slightly lower than the water source, so that the ponds can be filled by gravity rather than by pumping.
Supplying water by gravity greatly reduces energy inputs and operating costs. In most cases, the larger the surface area (with gentle slope), the better. This is only true if the land and water are not expensive.