Cabomba (Fanwort) Aquarium Plant Care Guide

Cabomba is an amazing background aquatic plant, popular in the aquarium hobby. It is delicate but easy to care for. It offers safe retreats for fry and small fish, consumes extra nutrients in your tank, and releases oxygen.

Some Basics

Scientifically known as Cabomba Caroliniana, the Cabomba is a popular freshwater stem plant available in most pet stores.

  • Colors range from grass to olive-green, and sometimes reddish-brown. The green Cabomba is more common than the purple (red) variety.
  • It has short, fragile rhizomes.
  • It is found sometimes floating but more often rooted.
  • The leaves are either submerged or floating.

The submerged leaves look like fans, hence the plant’s common names: Carolina fanwort, Carolina water shield, fanwort, fish grass, or Washington grass. The Cabomba grows small, white flowers on thin stems above the water’s surface.

by Mark Hanford [CC BY-SA 2.0]

This plant is native to southeastern South America (Paraguay, Uruguay, southern Brazil, and northeastern Argentina) and the West and East coasts of the US.

Cabomba usually grows in slow-moving water streams and small rivers, ponds, lakes, or sloughs. It reproduces through seeds and broken stems driven away by flowing water. Its fast reproduction and tall stems make this plant an excellent background for most small and large tanks.

Keeping Cabomba

These plants are easy to care for and are great for beginners.

The plant requires medium to strong light for at least 10 – 12 hours daily to simulate the bright summer daylight in its habitat. Lower light will weaken the stems and make them break like they do in late summer.

by HQ [CC BY-SA 2.0]

The red and purple Cabomba will need even more light than the green ones. Most hobbyists prefer fluorescent bulbs, which are the most effective in supporting plant growth. LED lights are the second choice.

Cabomba’s sensitive stems will need slow-moving water. Stronger currents may uproot the plants or break them apart, creating a mess of leaves in the tank. In addition, they are not the best plants for rough fish like goldfish or cichlids, which can nibble on them or break the stems while swimming.

Cabomba thrives in the following conditions:

  • pH: 6.8 – 7.5 (although some aquarists have noticed it can also handle a lower pH)
  • Water hardness: soft to moderately hard
  • Temperature: tropical, between 72 – 82 degrees Fahrenheit
  • Lighting: Full-spectrum medium – strong for extended hours (at least 3 watts/gallon)
  • Tank size: all tank sizes

Cabomba is a great pond plant that will create a nice, dense, underwater bush.

by Plant Image Library [CC BY-SA 2.0]

As they grow and spread quickly, plant them in a shadier corner of your pond, or an area with cooler water, to keep their growth under control. Keep an eye on them and trim them from time to time to prevent them from taking over the whole pond.

Planting and propagating

Cabomba is easy to plant on any substrate. Insert the stems about one inch deep using a pair of tweezers. Their sensitive roots and stems may break if handled too roughly. Pack the substrate only a little around the stem while securing them to prevent uprooting and floating around.

You can use lead weights until new roots develop in a few days. Plant individual stems one inch from each other to allow them to grow freely.

by Andrey Zharkikh [CC BY 2.0]

In the wild, the Cabomba is usually found in loose substrates where it doesn’t root too much. It commonly lives on sand, cobble, or rock ledges. As this plant absorbs nutrients from the water column and not the substrate, it doesn’t matter too much what substrate you use.

You can keep Cabomba floating. Being closer to the light source while floating will make the plant grow faster and give it a chance to flower. In a tank with lower light, keeping a floating Cabomba will help it get more light. However, floating Cabomba usually don’t look as good as planted ones

As Cabomba grows fast, it may soon take over your tank and invade the water’s surface. It may block the light from getting to the bottom plants, so you will want to trim it from time to time. You must be careful when trimming, but it’s relatively easy.

You need to cut the stem gently where you want it and discard the cuttings. If the cuttings are more than three inches long and are healthy, you can use them to propagate the plant. Plant them in the substrate or allow them to float and grow new roots.


While the plant does well in high light, it will need constant fertilizing to boost growth and promote the development of fresh shoots. Growing a healthy Cabomba without constant fertilizing is very hard, even with proper lighting, as it keeps consuming the nutrients in the water column.

CO2 dosing

CO2 is also vital for healthy growth. While extra CO2 is not vital, it will greatly benefit the plant and help it grow faster and more beautiful. In exchange, the Cabomba will help oxygenate the water well. However, too much CO2 can harm fish or other sensitive plants, so start with smaller quantities, observe the effects, and slowly increase only if necessary. Beware that losing appetite and sluggish fish movement means too much CO2 in the water. If fish begin gasping for air at the water’s surface, stop dosing immediately and perform a large water change

If nutrient levels get too low, leaves will begin to darken, and the stems will grow long, with very few leaves. The plant will also start shedding its leaves when not getting enough CO2. A healthy-looking plant will have bright green leaves or rich gold and pinkish hues in the case of red varieties.

by Mark Hanford [CC BY-SA 2.0]

Extra CO2 may encourage algae to grow faster than the Cabomba. This may solve itself over time as the plant grows and expands, taking up more nutrients in the tank and inhibiting algae growth.

However, when algae keep growing despite the plants growing and looking healthy, there may be a high light–nutrient imbalance (including CO2). If the light is correctly set, test the water for nutrients to see where the problem might be.

Also, CO2 needs may be different for low-light and high-light tanks. High-light tanks may need double the amount of CO2 supplements as plants grow faster. Carefully read the instructions on the package. If unsure about the dosing, add the needed quantity once every two days, even if it says every day. Evaluate the results after two weeks and increase the dosing to daily if needed.

Legal aspects

Although native to South America and some North American regions, the fanwort has also found its way across the US, Europe, and Asia.

Some States like Connecticut, California, Massachusetts, Maine, New Hampshire, Vermont, and Washington have made it illegal to propagate and sell this plant due to its quick spreading and invasive behavior. This is also the case in Canada, some Asian countries, and the EU.

If you already owned a Cabomba before the law entered into force, you are allowed to keep it, provided you dispose of any cuttings responsibly, ensuring it doesn’t reach a water stream and propagate. Throw the cuttings in the garbage disposal or compost.

Cabomba benefits

Cabomba suppresses algae growth by absorbing the extra nutrients and out-competing them. It absorbs chemicals like nitrates, phosphates, CO2, ammonia, and substances from fish waste and decaying plants, thus acting as a biological filter.

Its dense foliage provides hiding places for shrimp and fry. This offers extra protection to small tank life. Bettas may enjoy the shady areas provided by floating Cabomba, which can double as feeding stations. Place a few pellets between the floating stems and allow the fish to pick them.

Cabomba creates a beautiful forest-like background.

Tank mates

Generally, Cabomba will do well in tanks with peaceful fish and invertebrates, which move slowly and won’t nibble on plants. Some good tank mates are guppies, neon tetras, cories, rasboras, cherry barbs, shrimps, nerite snails, or trapdoor snails.

Cichlids are too harsh on these delicate plants and can break them, while bettas may graze on them and create a mess of leaves in your tank. However, they are not poisonous to the betta and will provide plenty of hiding places to nap.

In Conclusion

The beautiful and delicate Cabomba is a bit challenging to plant and keep, as you need to monitor the water parameters closely.

Ensure it has enough light and doesn’t overgrow, especially when floating. It is a good match for peaceful tanks with slow currents and gentle inhabitants. It consumes excess nutrients, provides oxygen, and can make a nice vegetable snack for your fish.

If you want to read more articles about plants, please visit our posts here.

About the author

Hi, I am Laura. I love fish and pets in general.
I have researched aquariums extensively. I have worked in pet stores, helping customers do the right choices. I am also the owner of two cats.

You can find the articles I wrote here

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