Prawns: Pond Construction

Production ponds for freshwater prawns should have many of the basic features of ponds used for the culture of channel catfish. Special attention should be taken in analyzing soils and water source for the presence of pesticides when evaluating site selection. It is also critical to construct the pond in such a manner to facilitate the draining and harvesting of ponds.

Site Selection

Well water is the preferred source for raising freshwater prawns. Although surface water or runoff can be used, the quality and quantity is subject to change. Some water quality characteristics considered necessary include 90 days of water temperature greater than 68º F, pH that ranges from 7.0 to 8.5, and a water hardness that ranges from 15 to 300 mg/L. Ponds should not be constructed in areas that are subject to periodic flooding.

Almost all pesticides are toxic to prawns. Therefore, ponds should not be constructed in pesticide-contaminated soils, in areas that are subject to drift from agricultural sprays, or in areas exposed to runoff water that may be contaminated.

Pond Morphology

The surface area of growout ponds should ideally range from one to five acres. Although successful production has been achieved in larger ponds, the logistics of management and harvest present some problems. The shape of the pond should be rectangular, thereby facilitating the distribution of feed across as much of the surface area as possible. The bottom should be free of obstructions to seining. It should also be free of depressions that allow prawns to evade seining or become stranded if a drain harvest is performed.

Ponds should have a minimum depth of 2.15 feet at the shallow end and slope to a maximum depth of 4 feet. A four inch drop in elevation with every 100 feet of pond length should allow for rapid draining. A smaller slope may contribute to the formation of small pools of water that may lead to prawns becoming stranded during a drain harvest. A slightly deeper (four to six inch) area of 15 to 20 feet should be constructed around the drainpipe to allow prawns to congregate during drain harvest. See larger view of drawing.

Drainage Structures

Best results for draining and harvesting of ponds with one to three acres of water surface have been realized with one 14 to 16 inch diameter drain pipe or two 8 to 10 inch diameter drainpipes. With the flow capacity of these pipes, full draining of most ponds will occur within 24 to 48 hours. Provision of at least two pipes also provides backup if one pipe should become obstructed. Draining of the final 1 foot of water should be sufficiently slow to allow time for prawns to either collect within the “in-pond” catch basin or pass through the drain for collection outside the levee. Some prawns may still have to be removed from the pond bottom as the final water drop may strand some in soft muds.

Liming the Pond

The soil pH should be determined before filling the pond with water. Collect soil samples at six different locations from the bottom of a newly constructed pond and mix them together to make a composite sample. Place the sample in a soil-sample box -- available from the county offices of MSU Extension Service -- and send it to the MSU Extension Soil Testing Laboratory or another soil-testing laboratory to determine pH. If the pH is less than 6.5, apply enough agricultural limestone to increase the pH to at least 6.5, or preferably 6.8.

Photo of pondProviding Substrate

Providing habitat or substrate has resulted in as much as a 25% increase in total production in experimental ponds. A comparable increase in production has yet to be demonstrated in commercial production ponds containing substrate.

Substrate is any two- or three-dimensional material that can be added to fill the water column and serve as additional habitat. The most common material used in research investigations is an orange PVC barrier fencing used around construction sites. It is UV stable and can be used for multiple years without degradation. Other materials such as bird netting or old fishing nets have also been used. Cost and availability are important considerations in reducing the proportional costs of this material to overall operational costs.

If substrate is to be used, it should be suspended vertically in the water column and the surface area of both sides should be equivalent to at least 50% of the surface area of the pond. Reinforcement bars are positioned every 25 feet to support the vertical substrate within the water column.

MSU Publications & Information

Other Freshwater Prawns Information

Link to larger image of drawing