A Balanced Ecosystem - An Aquarium | WWF

A Balanced Ecosystem - An Aquarium

The term ecosystem describes both the living and non-living components of an area that interact with one another. All the components are inter-dependant in some way with each other. An ecosystem may be aquatic or terrestrial.
In an aquatic ecosystem rocks are needed for shelter and plants provide oxygen for fish. An ecosystem is balanced when the natural animals and plants and non-living components are in harmony- i.e. there is nothing to disturb the balance. With increasing pollution, change in migratory patterns, and rise of human population, many ecosystems are in danger of losing that harmony.

It is difficult to find a perfectly balanced ecosystem but you can make a model at home and observe how the ecosystem functions.
  • You can observe how different species interact with each other
  • Study the natural cycle of each species
  • Understand the relationship between different species- producer, predator, prey

How to create a balanced ecosystem model

Here is a suggestion for making an aquatic ecosystem- an aquarium. You will need:
  1. River silt or clean sand for the aquatic plants to grow.

  2. An aquarium tank, at least 1 foot wide, 2 feet deep and 2.5 to 3 feet long. The top of the tank should be detachable and foldable so that you can reach into the aquarium to clean the glass sides and also feed the fish.

  3. A light attached to the top lid to provide artificial light and for warming during cold winters. You can also place the aquarium at a sunny place.

  4. Aquatic plants.

  5. Small rocks for the bottom.

  6. Fish.
First clean the soil and put it in the bottom of the tank. Arrange the rocks. Then pour a little water into the tank. Pouring the water directly will disturb the soil bed; so pour it over a plastic plate that floats over the surface of the water.

This way you will not disturb the bed or any other plants or fish when you pour water. When the water is at least 1 inch higher than the bed, put the plants into the soil. As the water level goes up the leaves of the plants will also rise up.

After the tank is full with about 4 inches left on top, stop pouring the water. Let the water settle for some time. Now introduce the fish one by one and close the top.

Observe whether some fish are destroying the plants or whether some fish are eating other fish. If the population of one species goes down dramatically, try and find the reason why this has happened. See what will bring back the balance- is it more fish of the same species, places for them to hide and be protected from predator fish, or more oxygen in the water?

For your project display, describe the abiotic (nonliving) factors present. Explain why the living and nonliving elements are needed in the aquarium. Give reasons for selecting the organisms or type of fish and the plants. Explain what relationship the fish have with each other and the plants- are they prey-predator? Show where they are in the food chain. Note their life cycle. Describe their adaptations and interactions with each other and the environment.