plastic aquarium plants turning black (Solutions, Causes)

plastic aquarium plants turning black

Plastic aquarium plants are a popular choice among fish tank owners for their low maintenance and long-lasting durability. However, a common problem that can occur with plastic plants is when they start to turn black. This can be for aquarium owners who want to maintain a clean and healthy tank environment for their fish.

In this blog post, we will explore the causes of plastic aquarium plants turning black and provide ways to prevent and treat the problem.

Causes of Plastic Aquarium Plants Turning Black:

  • Algae Growth: One of the most common causes of plastic aquarium plants turning black is algae growth. Algae thrive in warm, stagnant water, and can attach themselves to any surface, including plastic plants. Over time, this can cause the foliage to discolor and develop black spots.
  • Bacterial infection: Another reason for plastic aquarium plants to turn black can be due to bacterial infection. This can happen when the plant is not cleaned properly and bacteria begin to grow on the surface of the plant. This can lead to discoloration and darkening of plant material.
  • Poor water quality: Poor water quality can also contribute to the blackening of plastic aquarium plants. If the water is not properly filtered or if waste and debris accumulate in the tank, it can create a breeding ground for bacteria and algae, which discolors the plastic plants.

Solutions for Preventing and Treating Black Plastic Aquarium Plants:

  • Regular Cleaning: The best way to prevent plastic aquarium plants from turning black is to clean them regularly. Use a soft brush to gently clean the surface of the plant and remove any algae or bacteria. Be sure to use aquarium-safe cleaning products to avoid harming your fish.
  • Improve water quality: Maintaining a clean and healthy tank environment is key to preventing black plastic algae. Ensure regular water changes, maintain adequate filtration, and monitor water parameters to ensure optimal water quality.
  • Replace old plants: If your plastic plants are old or have been in the tank for a long time, they may be more prone to blackening. Consider replacing old plants with new plants to prevent discoloration and improve the overall aesthetics of your tank.

How do you get black algae off plastic aquarium plants

Black algae, also known as black bear algae, can be difficult to remove from plastic aquarium plants. Here are some steps to remove black algae from your plastic plants:

  • Step 1: Remove the plant from the tank and rinse it under running water to remove any loose debris or algae.
  • Step 2: Mix a solution of 1 part bleach to 19 parts water in a container. Place the plant in the solution and let it soak for 10-15 minutes.
  • Step 3: After soaking, remove the plant from the solution and rinse thoroughly under running water. Be sure to rinse the plant thoroughly to remove any residual bleach.
  • Step 4: If any algae remain on the plant, you can use a soft brush or toothbrush to gently clean the surface. Be careful not to damage the plant material.
  • Step 5: Rinse the plant again under running water and return it to the aquarium.

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Why is my fish tank decorations turning black?

Fish tank decorations can turn black for a variety of reasons, including algae growth, bacterial infections, and poor water quality. Black algae, in particular, can attach to any tank surface, including decorations, and can become discolored over time.

Is black algae harmful to fish?

Black algae are usually not harmful to fish, but it can be an indication of poor water quality. If left untreated, black algae can continue to grow and spread, causing tank damage and potential health problems for the fish.

How long does it take for black algae to go away?

How long it takes for black algae to go away will depend on the severity of the problem and the treatment method. Removing infected decorations and thoroughly cleaning the tank can help remove algae quickly. However, if the underlying cause of the problem, such as poor water quality, is not addressed, algae can continue to return. Regular maintenance and monitoring of water parameters can help prevent the growth and spread of black algae.


The blackening of plastic aquarium plants can be an annoying problem for fish tank owners. However, by understanding the causes of this problem and implementing proper precautions, it is possible to keep your plastic plants fresh and vibrant. Regular cleaning, proper water quality, and replacement of old plants can help prevent and treat black plastic aquarium plants. With these simple solutions, you can enjoy a clean and healthy aquarium environment for your fish and plants.