Fish Pond Construction – SS2 Livestock Farming Lesson Note (First Term)

A fish pond is a constructed water body in which fish are raised. Building one starts with choosing a site with year-round water, clay soil, a gentle slope, security and road access. The farmer then designs the dyke, core trench, inlet, outlet and monk, and prepares the pond by clearing, liming, fertilising, filling and resting it before the fish arrive.

Behavioural objectives

By the end of the lesson, students should be able to:

• State the factors to consider when selecting a site for a fish pond.
• Name and describe the main parts of a pond design.
• List, in order, the steps for preparing a pond before fish are put in.
• Name the materials needed for earthen, concrete and plastic/tarpaulin ponds.
• Identify common mistakes in pond construction and management.

How do you select a site for a fish pond?

Before you dig a single hole in the ground, you have to be sure you are in the right place. Choosing a bad spot is the quickest way to lose money in fish farming. A farmer must look for the following:

1. Water availability: Water is the “blood” of the pond. You need a place where water is available all year round, not just during the rainy season. A nearby stream, a borehole or a spring is suitable.
2. Soil type (the clay test): This is the most important factor for an earthen pond. The soil must be able to hold water. Clay soil is the best because it acts like a plastic bowl. Sandy soil is bad because water soaks through it like a sponge.
3. Topography (the shape of the land): Gently sloping land is better than flat or very steep land. A little slope helps you drain the water easily at harvest.
4. Security: Do not build where thieves can easily reach your fish or where crocodiles and monitor lizards live.
5. Accessibility: A truck should be able to reach your farm to bring feed or carry away the fish you have sold. If the road is too bad, your business will struggle.

What are the parts of a pond design?

Once you have the land, you need a plan. A pond has specific parts that help it function.

• The dyke (the wall): This is the wall of earth or concrete that holds the water in. It must be wide at the bottom and narrower at the top to be strong.
• The core trench: This is a “secret wall” inside the dyke, usually filled with extra-packed clay, to prevent water from leaking underneath.
• The inlet: This is the pipe or channel where fresh water comes into the pond. It should have a screen (mesh) to keep out trash or wild “enemy” fish.
• The outlet (spillway): This is where excess water leaves. It helps prevent the pond from overflowing during heavy rain.
• The monk: This is a structure used to control the water level and to drain the pond completely during harvest.

How do you prepare a pond before the fish arrive?

You do not pour in water and add fish immediately. You have to “prepare the house” so the fish do not get sick or die.

1. Stumping and clearing: Remove all trees, roots and grass from the area. Roots left behind will rot and make the water smelly and toxic.
2. Liming: This is like “disinfecting” the soil. Spread lime (calcium carbonate) on the bottom of the pond. It kills germs, balances the acidity of the soil and makes the water clearer.
3. Fertilisation: Add organic manure (such as poultry droppings) or chemical fertilisers to make plankton grow. Plankton is made up of tiny plants and animals that float in the water, and it is natural food for young fish. If your water looks slightly green, there is plenty of natural food for the young fish.
4. Impounding (filling): Let water into the pond slowly. Do not fill it to the brim, so that it does not overflow when it rains.
5. Letting it rest: Wait for about 7 to 10 days after fertilising before putting your fish in. This gives the “good organisms” time to grow.

What materials are needed to construct a pond?

Depending on the type of pond, a farmer needs different tools and materials.

• For earthen ponds: You need excavators (or many labourers with shovels), head pans and clay.
• For concrete tanks: You need cement, sharp sand, gravel and “waterproof” chemicals to mix with the cement.
• For plastic/tarpaulin ponds: These are “above-ground” ponds. You need a strong wooden or iron frame to hold the weight of the water.

What common mistakes should a farmer avoid?

As a student or a future farmer, remember these “red flags”:

• Building in a flood zone: If the river overflows and enters your pond, your fish will swim away into the wild.
• Using too much manure: Too much manure in the water uses up all the oxygen, and the fish will suffocate.
• Leaky dykes: If you do not pack the soil properly, you will keep losing water and spending money to refill it.

Teacher’s tip

Always remind students that water quality is more important than the fish itself. If the water is good, the fish will grow. If the water is bad, even the best fish will die.

Evaluation

1. State four factors a farmer should consider when selecting a site for a fish pond.
2. Why is clay soil better than sandy soil for an earthen pond?
3. What is the function of the monk?
4. Why is lime spread on the bottom of a pond?
5. Why should a farmer wait 7 to 10 days after fertilising before putting fish in the pond?

Assignment

1. List the five steps for preparing a pond in the correct order and give one reason for each step.
2. Describe three common mistakes in pond construction and management, and state the problem each one causes.