A farmer considering culturing fish needs to consider a number of factors that may affect the success and profitability of the enterprise. Surveys for suitable sites or evaluations of specific sites should first identify strengths and weaknesses of physical characteristics such as the suitability of the soil, the topography of the land, and the availability of good quality water.
Evaluations should also consider market demands, proximity to markets, and the availability of needed inputs such as fertilizers and feeds and other resources. In addition, all existing and planned uses of the catchment area (the farm) should be studied to determine how they might contribute to or interfere with the farming enterprise.
This series addresses the questions of selecting good pond sites.
Selecting a Good Pond Site
In land-based aquaculture, the most commonly used culture units are earthen ponds. When evaluating and selecting sites for earthen fish ponds, the main physical factors to consider are the land area, the water supply, and the soil. The following points should be kept in mind for each. For concrete or plastic ponds, the pond site consideratons is mainly related to having good and constant water supply to these ponds and the drainage systems you have in place, if your are not recycling your water and you are in a residential area, you have to make sure your drainage (soakaway) is very effective and it doesnt disturb your neighbors.
• Establish that the land is relatively level. Steeply sloped land is not generally suitable for building ponds. A slope of about 1% is considered ideal.
• Determine that the area is large enough for your present plans and for any future expansion.
• 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 runoff from adjacent land. Find out who owns adjacent and uphill land, how they use the land, and what chemicals (including fertilizers 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.
• Consider development plans for neighboring areas and assess any causes for concern.
Relatively level land, as pictured, is most suitable for building earthen ponds. Steep hillsides or very rocky areas are not suitable.
A good water source is one that provides high quality water in sufficient quantity throughout the year. Supplying water to ponds by gravity is preferable.
The most common sources of water used for aquaculture are surface waters (streams, springs, lakes) and groundwater (wells, aquifers). Of these, wells and springs are generally preferred for their consistently high water quality. For concrete and plastic ponds, borehole, well and pipeborne water are the most common.
• The quantity and quality of water should be adequate to support production through seasonal fluctuations.
• Determine that the quality of the intended water source is good enough for fish to thrive.
• A good water source will be relatively free of silt, aquatic insects, other potential predators, and toxic substances, and it will have a high concentration of dissolved oxygen.
If fish are already living and reproducing in the water (for example a river or lake), this is usually an indication that the quality is good.
• Find out if the quality remains constant throughout the year or if there are seasonal changes that result in poor quality at certain times.
• Make the final site selection based on both the quality and quantity of water available.
• The quantity of water required depends on the species (Catfish and Tilapia are the most common in Nigeria) to be cultured and on the anticipated management practices, for example whether ponds will be operated as static ponds (no water flowing through) or as flow-through systems (Constant water supply). Warmwater species like tilapia and catfish can tolerate water with lower dissolved oxygen levels, so their culture is often done in static water, that is, without water flowing through the ponds. However, the best situation is to have a lot of “free” water, meaning water available by gravity flow, even if it is not always being used.
• For earthen ponds, the water source should be able to provide at least 1 m3 of water (1000 litres) per minute for each hectare of ponds that will be built. This quantity will be sufficient for quickly filling the ponds as well as for maintaining water levels throughout the culture period. For concrete and plastic ponds, you should be able to change out the water at once in one or two weeks depending on your stocking density and feeding ratio.
• If the selected site has relatively poor soils (i.e., soils containing too much sand) the source should be able to provide two to three times more water (2-3 m3 per minute per hectare). This quantity of water will be sufficient for maintaining water levels to compensate for losses that are likely to occur through seepage.
• Land should be composed of good quality soil, with little or no gravel or rocks either on the surface or mixed in. Areas with rocky, gravelly, or sandy soil are not suitable for pond construction.
• The soil should be deep, extending down at least 1 metre below the surface. There should not be layers of rock lying close to the surface.
• Soils in the area where ponds will be built should have clay layers somewhere below the surface to prevent downward seepage.
• Soil that will be used to build the dykes must contain at least 20% clay so the finished pond will hold water throughout the growing period.
• Some soil with a higher clay content—preferably between 30 and 40%—should be available nearby. It will be used to pack the core trenches in the dykes.
Other factors to consider
1. Proximity to a market
• Does market demand justify production?
• Will the existing physical infrastructure meet the farmer’s needs
for marketing the fish?
• Will there be sufficient demand nearby or will transporting to a distant market often be a necessity? It is easier to sell at your doorstep or to have a permanent buyer who takes everything you can produce and either picks the fish up or is close enough that you can deliver the fish to them.
Infrastructure • Are the roads good enough to bring supplies to the farm and take the product to the market?
• Are telephone service and electrical power available at the site? If an intensive production system is necessary due to constraints of space or water, access to power is a must. Electrical power being what it is in Nigeria, generating sets that consume fuel are your best bet and they are expensive, so if you don’t have a free flowing source of water, this will definately increase your cost of operation.
Availability of needed inputs
• Are fertilizers and lime available at reasonable cost?
• Are fingerlings available at a reasonable cost and distance?
• Are fish feeds available for purchase, or are suitable ingredients available so the farmer can produce his own?
• Hire qualified people as farm staff. Raising fish requires specific knowledge acquired only through training. However, training is not the only criterion to use when selecting workers: Look for workers who can be taught and are willing to learn, they should also be dedicated to a successful operation and most importantly of all, be trustworthy. Their is no point employing an expensive “trained” farmer that steals from you.
Access to Technical Advice
• Be sure good technical advice is readily available. Local extension agents or trained consultants are good possibilities. Remember technical advice can be expensive and is sometimes wrong. Doublecheck advice received with a qualified individual (meaning they
have produced a few tons of fish before) who is sincerely interested in your success. Good consultants admit when they don’t know the needed information.
• Consider both criticism and compliments very carefully: The best advice may come in the form of criticism, and compliments can be misleading.
• Horticulture and animal husbandry consultants may know about business planning for agriculture but probably do not know enough about fish farming to give proper technical advice.
• Know who your competitors are and how much they sell their fish for. Consider whether you will be able to match their price and quality or even outsell them by producing a better product or selling at a lower price.
• If fish demand is high, cooperating with nearby fish producers to market the fish might be a possibility. The presence of several fish farmers in an area may make it possible for inputs to be obtained less expensively by forming a purchasing block (cooperative or group).
Consider whether or not there are any legal issues that will affect your ability to culture fish at this site. Would any of the following prevent you from going into fish farming: Land Use Act? Water Act? Environmental Acts? Others?
If your site is suitable for pond construction with respect to land, soil, and water, and if you are satisfied that other selection criteria have been met, you can go ahead with planning. In the next series we will be addressing marketing the fish that have been produced.