Types Of Pond

There are different types of fish ponds used in the aquaculture industry. These different types of ponds require different materials & methods for construction. Whichever type of pond you use, there should be provision for fresh water intake and waste water discharge which should be at different ends of your pond. The pond types are: 

1. Earthen Pond

It is a dug out pond usually constructed in lowland areas, swampy areas and mangrove vegetation. 

1a. Constructing Earthen Ponds

Having selected a good site, a topographic survey map of the site with farm layout and the design of the individual pond should be drawn to establish the orientation of the pond. The pond would then be marked out. Suitable sizes of the pond are between 0,01Ha – 1.0Ha. For semi- intensive system pond, sizes above the range are difficult to manage and should be avoided. For a small pond 15x30meters, a dyke with a base of 4meters should be measured. The total land area would be (4m+15m+4m) x (4m+30m+4m)= 23m x 38m. 

The top soil which often contains organic matter is removed up to 20cm and heaped aside. Another rectangle of 15m x 30m should be marked within the first one. Plan the location of the outlet and the inlet structures. Dig out and place pipes of appropriate diameters. The outlet pipes should be 10-15cm in diameter and 6m in length. The soil from the inner rectangle is used to build the dyke. The pond bottom is sloped towards the drains for complete drainage of water from ponds.  The total length of dyke vertically should be 1.65m. 

Wooden or concrete monk is constructed to link up with the drainage pipe buried. The inlet pipe is also laid (at the opposite end) to connect with water supply channel. A screened sluice is placed to regulate the rate of water inflow and to prevent wild fish and other organisms from entering the pond. The top fertile soil removed earlier is spread evenly on the pond dykes and bottom. Grasses like bahama grasses are planted on the dyke to prevent dyke erosion. 

1b. Pond Preparation

For newly constructed ponds, preparation entails liming, filling with water and fertilization. Preparation of old ponds requires draining, desilting, drying, repairing, liming, water filling and fertilization.

1. Liming

1. Liming helps to neutralize acidity of the pond bottom 
2. Release valuable fertilizing material in the mud.
3. Eliminates undesirable organisms in the pond.
4. Reduce water turbidity.

The quantity needed depends on the soil acidity and pond size. Calcium carbonate (CaCO3) is spread evenly on the pond bottom. Partial filling of water is done the following day after liming before fertilization.

2. Pond Fertilization

Fertilizers added to pond s contain important nutrients (nitrogen & phosphorus) which are essential to the growth of natural fish food organisms. The two categories used are organic (e.g. animal droppings, and decomposed plant residues) and inorganic (e.g. Single super phosphate, triple super phosphate and ammonium sulphate). The quantity needed depends on the richness of pond water and the type of fertilizer. Up to 3000kg/ha/yr of organic fertilizers and 1000-1500kg /ha/yr of inorganic fertilizer are needed in semi-intensive culture system. The initial application takes half of the above while the remaining half is applied at two weekly or monthly intervals depending on the pond condition.

Fertilizers could be applied using any of the following methods:

1. By broadcasting on the pond water surface 
2. By placing on platforms under water for easy distribution by water currents.
3. Putting it in plastic buckets and sprinkled into water
4. Place in jute bags and submerge under water to dissolve slowly
5. Decompose plant residues could be dumped in pond corners where there are prepared cribs.

Fertilization should be discontinued when there is high turbidity to avoid algae bloom. The right plankton production can be determined by the use of secchi disk. The water level would now be raised to the required level of at least 1 meter and fish stocked.

2. Concrete Pond

It comes in different shapes and sizes. The only unique feature of most concrete ponds is that it is mostly rectangular in shape with one end having the inlet pipe(s) (fresh and / or recycled water) and the other end having the discharge pipe(s) (waste water). It can be constructed by casting with concrete and iron rod or by setting of 9 inches block and filling the holes with concrete. Whichever way it is done , the pond is plastered properly to prevent leakages. The piping can be done as either conduit or surface to convey water in and out of the pond. 

3. Wooden Vats

Wooden boxes lined with tarpaulin / nylon materials. It should be constructed in a manageable size with hard planks and sticks. The outlet is drilled at the base of one end with back-nut attached while the inlet pipe is connected to the other end.

4. Mobile Tarpaulin Fish Ponds

It is constructed with pipes and tarpaulin material. The pipe is just to serve as a frame to give shape and support the tension while the tarpaulin rest on the floor of the farm. There is the imported brand and the type designed locally by Tritech Business Solutions.

5. Plastic Tanks

This was developed specifically for fish farmers by the producers of various brands of overhead tanks. It could be the round shape open tank with an arch shape cover or rectangular shape. Some use imported chemical tanks with galvanized iron frame which are cut at the top to create an opening. Caution: be careful not to wash the chemical off on your farm premises as a seepage may contaminate your bore hole water especially in sandy soil terrain. 

6. Cage Culture

It is constructed on the Lagoon, Rivers or Earthen ponds. It is made with PVC pressure pipe, trawler nets, floaters, sinkers and twin for stitching.

7. Glass Tanks

This type of tanks is popular with ornamental fish producers and catfish hatchery. It is made with glass material cut to size and glued together with silicone sealant. The water outlets are created to size by glass cutters.

    Transparent glass tank     Dark glass tank from West Farms Ltd

8. Fibre Tank

These are specialized ponds that could be constructed with wood and coated with a mixture of chemical material to make a fish pond. This is a specialized type of pond that is quite expensive to construct.

Fibre tanks under shade at Alex Farms