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Name: Anneke
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You can put pond weed in a goldfish tank instead of bubbling air through the water. Can you explain why this helps the goldfish to be more active, particularly during the day?


I am not familiar with your aquarium set up But if you are getting more active fish when you add pond weed It may just be that the green pond weed is better at oxygenating your water Than your air pump.

Pond weed and other green plants eat (absorb) (input) sunlight and Carbon Dioxide and Emit (output) oxygen in the process called photosynthesis. So your pond weed is adding oxygen to the water in your tank.

It may also be that the fish feel more at home with something natural in their habitat, and that the pond weed gives them an opportunity to hide in something instead of being under the glaring aquarium lights, or it may be a combination of all three factors.

Here is an article on photosynthesis for your further information:

Here is a less intimidating article: m

You can find other articles by going to and searching for "photosynthesis"

Keep chasing your curiosity by asking questions because that is how you get smarter.

Sincere regards,
Mike Stewart

Pond weed, like all plants, "breathes in" carbon dioxide and "breathes out" oxygen. Without some sort of plant life in a still pond, the water would become deoxygenated, which would make fish slow down their activity, if not survive all together. The more oxygen available to the fish, the more active they can become. My only guess to why it makes them more active during the day would be that the plants photosynthesize during the day due to the sunlight and would slow that process down in the dark, therefore decreasing their oxygen input into the water during the night.

Grace Fields

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