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red fish swiming among houseplants in fish tank

Houseplants & Fish Tanks: 14 Helpful Tips (For Beginners)

Have you ever considered putting houseplants inside your fish tank?

If so, it is incredibly important you do research into which plants will thrive but also be good for the fish, before you seriously damage your fish or your plants.

There are particular requirements you need to take into consideration.

Here are 14 answers about houseplants and fish tanks everyone should know before combining the two:

1. Can You Put Live Potted Plants In Your Fish Tank?

Yes, you can put live potted plants in the tank, as long as these plants are suitable for growing in fish tanks. Unsuitable plants will simply rot and fill the water with bacteria, and even suitable ones need to be planted in the right conditions in order to thrive.

Not all plants will be suitable for fish tanks, and we’ll go into more detail about which ones are further down, but it’s important to check before you put a plant in the water.

You also may need to add light to keep the plants happy, as they are unlikely to be close enough to a window.

2. Are Live Houseplants Good For Fish Tanks?

Live potted plants are very good for fish tanks. Even if you clean the tank out regularly, plant life is a big help in maintaining water quality, making both the fish and the water healthier.

It is certainly true that a fish tank with live plants in it will be much healthier.

Plants will do a variety of useful jobs while in the tank, including:

  • Absorbing carbon dioxide
  • Removing nitrates from the water
  • Removing phosphorus from the water
  • Fixing oxygen in the tank

In general, a fish tank without some form of plant life will not be very healthy for long.

This is because fish waste will build up in the water.

3. Do Live Houseplants Help Clean Fish Tanks?

Having houseplants in your fish tank will help to keep it clean, although it is not a complete substitute for cleaning. You will still have to clean up the tank yourself at times. 

Houseplants are a great way to prevent algal blooms in your tanks.

In the normal order of things, a fish tank without plants will undergo the following process:

  1. Fish eat food and excrete waste
  2. Decaying matter and uneaten scraps of food add to this waste
  3. The waste develops into ammonia, which is toxic and will quickly kill your fish if it is allowed to build up in the water
  4. Beneficial kinds of bacteria, known as Nitrobacter and Nitrosomonas, form and start to process the ammonia. They turn it into nitrites, and then into nitrates, which are less toxic
  5. The nitrates are safe at low levels, but as they start to increase, they will also become toxic to the fish
  6. Algae start to bloom in the water, because it is nutrient-rich and there is plenty for them to eat
  7. Your tank gets cloudy and full of greenery, ruining the view of your fish and spoiling the whole aesthetic

This is why most people prefer to put plants in the tank. The plants step in at around stage 6, and instead of algae forming, the plants will start to take in the nutrients.

This keeps the water clearer, because there is less for the algae to eat, and so less algae will form.

Overall, therefore, houseplants do keep fish tanks cleaner.

4. What Houseplants Are Safe For Fish Tanks?

Many plants are safe for use in fish tanks, but it is a good idea to choose the varieties that are best known for their safety, as your fish are likely to nibble on them.

Here Are The Safest Houseplants For Fish Tanks:

  • Syngonium
  • Lucky bamboo
  • Climbing fig
  • Golden pothos
  • Monstera deliciosa
  • Arrowhead vine
  • Java fern
  • Amazon sword
  • Water wisteria

Some of these plants are known as emergent, which means that they will come out of the top of the tank, growing into the air. Their roots and lower stems will be in the tank.

Others will be fully submerged in the water.

Both offer advantages, and you may wish to create a mixture for a varied and attractive aesthetic.

5. What Houseplants Are Toxic To Fish?

Of course, many plants are not safe for fish. If unsure about your particular houseplant, always do proper research.

Even better, buy your plants from a reputable aquarium stockist so that you can discuss your aquarium needs and make sure you are getting something suitable.

Do not put a houseplant into your fish tank without checking first that it is safe to do so. You might kill every fish in the tank if the plant is toxic to them.

Here Are Houseplants That Are Toxic To Fish:

  • Hemigraphis colorata
  • Dracaena godseffiana
  • Cordyline species “red edge”
  • Trichomanes javanicum
  • Chlorophytum bichetii
  • Dracaena deremensis

If you want to put other plants in and you are not sure about them, find a reputable aquatics store and get some advice.

6. Can Your Fish Eat The Houseplant In Their Tank?

Yes, your fish can safely eat or nibble at the houseplants in their tanks, as long as the plant’s species are safe for them.

If you have vegetarian fish, they certainly will eat the houseplants in the tank.

It is important to have a good amount of houseplants in the tank so that the fish don’t simply destroy all the greenery in sight.

You can also separate the houseplants from the fish, making it hard for the fish to access the leaves, but be aware that if you don’t do this, they will eat them.

7. Can You Plant The Houseplants In Your Fish Tank In Gravel?

As long as the gravel is aquarium safe, you can plant houseplants in it. The easiest way to do this is to get an elastic band and a fish safe rock. Attach the plant to the rock so that the rock sits just a little above the plant’s roots.

Once the rock is in place, bury it all in gravel. This will help to keep the roots down and prevent the plant from floating away.

Note that not all plants like being buried in gravel, so check out what the species you’re thinking of growing prefers before you plant it. 

8. Do You Need Soil For The Houseplants In Your Fish Tank

This will depend upon the plant, but many do enjoy being grown in soil. However, regular soil will float and make the water dirty, so you will either need to use soil based substrates or add gravel on top of the soil.

You are probably already aware that if you simply put a plant pot full of soil in your aquarium, the soil floats out and makes a mess. The plant gets uprooted, and nothing stays put.

The simple answer to this is to add a layer of gravel on top of the plant’s soil. This stops the soil from floating away and holds the plant down because it is heavy.

The other option is you can also purchase soil based substrates, which are essentially balls of soil that will not float off and make the water muddy. Note that they will eventually break down too, but it will take far longer.

9. Do Fish Tank Plants Need Grow Lights?

The plants in your fish tank will need light to grow. They are not going to get enough, even if your aquarium is fairly close to the window. Different plants need different light levels, but you should certainly think about how to install artificial lighting.

Your aquarium light will help a plant to grow, and for some plants, this will be sufficient.

However, aquarium lights are designed to cast an attractive glow on the fish and the tank, and therefore they do not have much red and blue light in them – which are the colors that the plants need to photosynthesize.

You may therefore wish to install a grow light near the tank.

Are Grow Lights Safe For Fish?

Grow lights are safe for your fish, but it is recommended that you turn them off overnight. This will be best for both your fish and your plants.

10. How Do You Put Houseplants In Your Fish Tank?

There are various ways to grow houseplants in tanks, and the method depends on the kind of plant. You can use gentle clips to pin the plants to the edges of the tanks so that the roots stay submerged.

You can also use the earlier technique of fastening the stem to a rock and submerging this in gravel.

Alternatively, grow your plant in a pot, cover the surface of the soil with gravel, and submerge the pot.

It’s possible to bury some plants, especially those that produce rhizomes, in the sand at the bottom of the tank. Put some small rocks around to prevent the roots from getting disturbed.

11. Common Houseplants You Can Put In The Fish Tank?

Many of the common and much-loved houseplants will grow perfectly happily in your fish tank.

You can try houseplants like:

  • Peace lilies, but you must only submerge the roots and stems, rather than the foliage
  • Pothos, which are easy to grow in aquariums and very popular
  • Golden pothos, which will bring a little more color to the tank than the standard green variety
  • Money plants, which must have their leaves above water, but will grow well with the roots submerged
  • Spider plants, which again need the leaves clear of the water, but will happily root in a fish tank
  • Monstera plants, which may grow their aerial roots into a nearby tank if it’s available. Note that these will quickly get too big for a fish tank, but they look great!

A few common houseplants that won’t work so well include those from the succulent family, and Snake Plants.

Succulents do not like being consistently kept wet; they need their roots to dry out, so they aren’t suitable for growing in an aquarium. They will simply rot if you try.

Snake plants may willingly grow in water, but they are quite toxic, and it is not a good idea to keep one in your fish tank.

12. How Can You Tell If Your Houseplant Is Safe For The Fish Tank?

Unfortunately, the only way to tell if a plant is safe to keep in a fish tank is to ask about that specific variety in a reputable aquatics store.

There is a lot of misinformation surrounding aquatic plants, even online, and many plants that are not suitable for aquatic growth are mistakenly sold.

Always check before adding a houseplant to your fish tank, or it could kill your fish.

13. Can You Propagate The Plant From Your Fish Tank?

This depends heavily upon the plant, but many plants from fish tanks can be propagated as normal. Take a cutting from the plant and put it someplace else in the tank, or you can even plant it in a pot.

Pothos, for example, will readily grow from cuttings, so if you want to increase your number of pothos plants, simply take a cutting and let it grow.

Many others, including Monstera plants, spider plants, and peace lilies, will also be reasonably easy to propagate.

Research the individual plant that you wish to propagate, and find out how to successfully take a cutting.

14. What To Do If The Plants Grow Out Of The Fish Tank?

You don’t need to worry if the plants in your fish tank start growing out the top. This is very common, especially with large plants such as Monstera, and it’s no cause for concern. In fact, emergent plants could be very good for the tank. 

Emergent plants often get more sunlight or at least more light overall, and therefore they will grow faster, and more efficiently filter nutrients out of the water.

This keeps your tank clean and free from algae, and protects the fish from a buildup of nitrates.

Don’t feel you have to cut back plants that are growing out of the fish tank. Instead, look for ways to support them so that they can continue growing.

Some people use cable ties, sucker cups with hooks, or even homemade hanging baskets to help stabilize their plants when they leave the water.

Final Thoughts

There are many houseplants that you can use to make your fish tank greener, brighter, and more natural.

Try any of the above varieties, or ask in your local aquatics store for more advice about which plants are best for the fish that you have.

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