Are Aquarium Plant Weights Safe for the Fish?

An empty fish tank is not only boring for us, but for the fish too. Plants add some color and dimension to our aquariums but are too light to sit at the bottom of the tank. Aquarium plant weights keep your tank’s decor secure, but are they safe for the fish?

Most aquarium plant weights are safe for fish. However, plant weights that contain lead or other toxic chemicals will harm your fish. Typically, if the plant was purchased at an aquarium store the attached weight will be safe for use in your fish tank.

Aquarium plant weights come in a variety of shapes and sizes as well as a variety of materials. Find out more about plant weights for your fish tanks and which materials are safe for use with your fish below!

What is an Aquarium Plant Weight?


In nature, plants secure themselves to the bottom of rivers, lakes, and streams through their roots. However, plants in our aquariums are purchased at aquarium/pet stores and have no roots of their own–unless you took the time to grow the plants in your aquarium from seeds.

Because aquarium plants don’t have any roots, they tend to float to the surface of the tank and eventually find their way into the filter.

To keep our plants secure–and out of the filter–until their roots attach, we use aquarium weights. Aquarium weights are made out of a variety of materials and come in all different shapes, sizes, and styles.

Although aquarium weights are a helpful tool in tank decorating, their safety and effects on fish health have been called into question. Keep reading to learn about all the different types of aquarium plant weights, and which ones are safe for your fish!

Types of Aquarium Plant Weights and How Safe They Are

Most household aquariums are on the smaller side and therefore don’t have the room for a large weight holding each plant down. Instead, fish lovers have had to search for smaller, heavier options to keep their plants secure.

The most commonly used plant weights in aquariums are:

  • Potted
  • Lead/Metal
  • Ceramic
  • Stone

Keep in mind, overtime fishkeepers (also known as “aquarists”) have developed many other methods for weighing down their aquarium plants. In fact, even these broad categories have a variety of substyles and designs.

Below each category will be broken down and its safety for your fish will be revealed!

Potted Aquarium Plants

Most of us have a potted plant somewhere in our house, but few of us have considered putting one in our fish tanks.

If you pull an aquarium plant out of its pot you may notice a different setup than a potted house plant would have.

Under the plant, you will likely find some small rocks and “rock wool”.

Rock wool is a fabric-type substance spun from volcanic rocks. It is used in agriculture and aquariums because of its ability to absorb both water and nutrients.

Potted aquarium plants can simply be set in the aquarium on top of the substrate (usually dirt or aquarium pebbles). If you choose to do this, just be sure to remove the rock wool from the pot.

If your plant came in a ceramic pot, this can be kept in the tank. It will not release any toxins that will harm your fish or other aquarium creatures.

This method will not require any extra weights, but if several potted plants are used it will take up quite a bit of the aquarium’s volume.

If you decide to replant your aquarium plants, simply remove them from the pot and add a different type of weight from the list below!


Lead/Metal Plant Weight

Now I know, the first thing you read earlier was that lead aquarium weights are toxic for aquarium use. However, this is not always true.

Not all “lead” plant weights are actually made from real lead. Most are made from other malleable metals that are safe for aquarium use.

When purchasing a “lead” plant weight, don’t be shy to ask what type of metal it is made from.

Metal aquarium weights are one of the most versatile ways to secure your plants. Why? Because of the malleability of the metal strips, you can tie your plant onto something or just attach the weight and bury it in the substrate.

Some fish keepers even glue their metal weights onto the plant!

Ceramic/Stone Aquarium Weights

Ceramic is a common material in aquariums. Although typically used as decoration, ceramics can also be used as a way to safely secure your aquarium plants.

Ceramic weights typically come in the shape of rings. This allows you to put the plant through the ring and bury it in the substrate. Another use for ceramic rings is to tie them to the plants before burying them.

Similar to ceramic weights are stone aquarium weights. Stone weights tend to be more ornamental and therefore are used to anchor plants on top of the substrate.

Be cautious when used stone weights as they may contain calcium. Over time, the calcium and other minerals will seep into the water. If you use stone or ceramic weights, frequently test your water’s pH to ensure it remains at a safe level.

Suction Cups

Technically, a suction cup is not a plant weight but is rather a plant anchor.

Using a suction cup to secure your aquarium plants allows you to not only attach plants to the bottom of the tank but the sides as well.

This is best for plants that prefer to float on the surface or throughout the tank. The plant is still able to have its roots exposed without clogging the filter!

So long as your suction cup isn’t made from cheap plastic, it shouldn’t break down. This method keeps your plants secure, your fish healthy, and your tank customizable.

DIY Aquarium Plant Weights

Maybe you don’t like the plant weight options described above, or maybe a trip to the aquarium store just isn’t ideal at the moment. Don’t worry, you can make safe, easy plant weights all on your own!

Most aquarists use materials such as cotton, fishing line, or zip ties to create their own aquarium weights.

For more ideas on anchoring your plants in your aquarium substrate, watch this quick DIY video!

If you like the article above, here are some other similar articles you should check out!

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How many hours of light do aquarium plants need per day?Opens in a new tab.

Rick Kesler

I'm Rick and I've kept freshwater fish for over 5 years now. My main tank now is a 55-gallon tropical freshwater tank and my wife and I both just love watching all of our different fish while they swim around, some schooling and others not. I've also learned a lot about what to do and what not to do to keep our fish healthy and happy.

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