article is written to assist prospective and practicing fish farmers and interested persons on the basics of how to identify good sites for earthen fish pond construction. Fish farming can be a profitable business if the rules of the game are followed in its management
A fish pond is an enclosure (earthen or concrete) built to retain water for the purpose of growing fish to table size for household consumption and for sale to generate additional income.
Consideration in selecting suitable sites
Every farmer or individual wants success in business enterprise, consideration in growing fish in pond involve the following steps below:
Water source and supply: - water is the medium for fish growth and it is the major limiting factor in fish culture. Water source must be free from pollutants, which are substances either in effluent or solid forms that are toxic to fish. Good source of water for fish pond includes; flowing river/stream, tidal flow from the sea, spring water, borehole/well water
Nature of the soil/land availability: - land is a universal factor of production, fish ponds are built on land either by excavating the soil or by building embankment structure. A prospective fish farmer should therefore ensure that the land is legally acquire this is important since fish pond structure can be maintained for as long as 10-15 years in production cycles. Soil at the site to be chosen must be tested for its capacity to retain water.
Topography: - these refer to the shape of the land, land that is sloppy but not exposed to soil erosion is suitable for fish pond. To supply water to the pond by free flow (gravity) the pond site should be at a lower level than the water source, therefore detail survey of the area should be carried out. However if the land available is flat, dugout ponds should be constructed with a slanting bottom to facilitate complete drainage of the pond
Vegetation of the site: - these involve the clearing and removal of grasses and tress that will damage to the fish pond construction
Constructing the pond
Once a suitable site has been selected and the land has been surveyed, construction can be done manually or mechanically, manual labour can be used for a small size fish pond planed. The steps involve in carryout construction are: -
Marking out the area of the pond : - the length and breadth measurement will be taken with the used of measuring tape and pegs to know the actual area to be dug for the inner core and outer core is the pond dike
Measuring and marking out the walls: - wall or dikes (dam) for fish ponds should be up to 0.5m thick and 0.5m high above the ground level. Strong pond wall will prevent collapse of pond structure of flooding periods
Excavating the pond: - this can be done manually or with machine. Earth or soil moved from the pond serves for construction of the dikes and the main parts of the pond to be constructed during excavation are the pond walls, the pond water inlet structure and the outlet structure
Embankment/pond wall building: - to impound and retain water in a pond, in most cases it is necessary to construct embankments,(embankment also known as dikes) are reinforced walls built above the ground level. The embankments should be strong enough to withstand water pressure and the height of the embankment should be at least 60cm above the highest water level that will be reached within the pond.