The pit test in pond construction helps you to determine whether the selected area is suitable to construct an earthen pond.
Dig a pit in the land area being evaluated, fill it with water, and observe how well it retains that water (better yet, dig and test a number of pits throughout the area).
Follow these steps:
- Dig a small pit about 50 cm in diameter to the probable depth of the possible future pond.
- Fill the pit to the top with water and let it stand.
- After 12 hours check the water level and pour in additional water to bring the level back to the top
- If possible, cover the pit to minimize evaporation.
- Allow the pit to stand undisturbed another 12 hours.
- After the second 12-hour period check the water level again. If the water level has not decreased more than about 3 cm, this soil is suitable for pond construction.
If the water level has decreased more than 5 cm, the soil may be too permeable and therefore not suitable for pond construction
With good management, your fish should be ready to harvest within six to nine months after stocking. By this time, tilapia should have reached a size of approximately 250-300 g and catfish a size of 250-500 g, depending on their size at stocking, the density at which they were stocked, and water temperatures during the growing period.
Preparing for the harvest
- Make marketing arrangements well in advance of the harvest date.
- Plan to harvest your fish early in the morning or early in the evening.
- Stop applying fertilizers one to two weeks prior to harvesting.
- Stop feeding the fish two days before harvesting.
- Set up all harvesting and transportation equipment well in advance. Contact fisheries personnel if you need guidance to acquire the right equipment for harvesting.
- Prepare the manpower.
- Partially drain the pond very early in the morning on the day of harvest.
- Begin seining in the shallow end of the pond and work towards the deep end.
- Work carefully, disturbing the pond bottom as little as possible.
- If possible, finish the seine haul near a water source in the deep end.
- If possible, spray a stream of fresh water over the fish while they are being held and handled.
- Gradually lower the water as you near completion of the harvest.
- Use a dipnet to move fish from the seine to buckets on the pond bank.
- Use cast nets, lift nets, hoop nets, or gill nets for harvesting if ponds are too deep or are not drainable, or if you do not have a seine.