Introduction: How to Make a Closed Aquatic Ecosystem

Do you want to create a self-sustaining aquatic ecosystem that will teach future generations about marine life and the environment around us?

Join us in creating an aquatic ecosystem in a half a gallon jar with a glass lid home for 3 Japanese Algae Shrimps with 2 Anacharis. This is an excellent project for school-aged children.

A closed ecological system will stay alive on its own without any outside input. The shrimp eat algae, and the algae and aquatic plants use the shrimps’ waste as food. Starting off with pond water is a great way to ensure that there will be ample algae and other beneficial microscopic organisms. Though it is not required for this project, the ecosystem will do better with a ventilation hole. This allows gas exchange with the outside environment. With proper ventilation, your ecosystem could live for a decade or longer!

Step 1: Gather Your Materials

  • Sealable Glass Jar with a rust-proof lid
  • Aquarium Gravel or Sand
  • Fresh Pond Water (or Algae pads if pond water is unavailable)
  • Leafy Plants for breeding and shelter. Some varieties popular with shrimp, found in local pet stores, include: Anacharis, Java Moss, Java Fern, Dwarf Anubias
  • Shrimp and/or snails. Ghost Shrimp, Cherry Shrimp, and Japanese Algae-eater make good choices.
  • Small aquarium net
  • Optional: moss ball, helps with breeding, provide additional shelter and trap phosphate in addition and/or substitute aquatic plants.
  • Power Drill
  • Glass drill bit
  • Eye protection

Note: If you don’t have access to pond water, use tap water instead and prepare the jar at least a day in advance to allow the water treatment to be completed. Shrimp need the algae from either the pond water or algae pads for nutrition before the plants produce their own.

Step 2: Drill Hole in Lid of Jar for Proper Aeration

CAUTION: Drilling through glass can be dangerous. Only an adult should use the drill. Use a glass drill bit and proper eye protection.

Step 3: Wash Jar

Step 4: Put 1 to 2 Inches of Gravel in the Bottom of the Jar, Enough to Anchor Your Plants.

Step 5: Collect Fresh Pond Water

Step 6: Fill Jar Halfway With Pond Water

NOTE: If you do not have pond water, use filtered or tap water and 1 or 2 algae pads depending on size of jar. Let sit uncovered for 24 hours to allow chlorine to evaporate.

Step 7: Float Bag With Shrimp And/or Snails in Jar for 15 to 30 Minutes.

This allows the temperature in the bag to equalize with water temperature in the jar, minimizing stress on the shrimp with a sudden change in temperature.

Step 8: Anchor Plants in Gravel

Step 9: Using the Net, Scoop the Shrimp Out of the Bag and Transfer Them to the Jar.

Step 10: Fill to About a Half-inch From the Top With Pond Water.

Do not leave too much airspace or you could get white deposits on the inside of the jar.

Step 11: Enjoy Your Ecosystem!

Keep indoors in indirect sunlight at room temperature and your ecosystem should last for several years.

NOTE: Keep out of direct sunlight to avoid algae overgrowth. You do not need to feed the shrimp since they eat the algae. It is unlikely that you will need to add water if you keep your aquatic indoors away from direct sunlight.

If you find algae overgrowth, try adding another shrimp or a few snails. In time, the ecosystem will come into a balanced state where the wastes of one organism are used as food by another organism. This is an excellent way to show children how our larger ecosystem recycles nutrients, with plants converting the carbon dioxide that we exhale into oxygen, and bacteria turning our wastes into soil nutrients for future generations of plants. Humans and animals, in turn, inhale oxygen and eat plants, taking those nutrients back into our tissues. It is quite beautiful how so much life can thrive by using the same molecules over and over again.