Pothos grows in aquariums with roots submerged and leaves above water

Pothos is one of the easiest plants to keep in an aquarium because it does not need soil and thrives with just its roots touching water. The plant sits at the edge or corner of your tank with stems trailing into the water—the roots absorb nutrients from the fish waste in the tank, and the leaves stay dry above the surface. You do not need special equipment, just a way to anchor the plant so it does not fall in.

The setup works because pothos is a semi-aquatic plant that naturally grows on trees and rocks near water in tropical forests. In your aquarium, it acts as a living filter: the roots pull nitrogen compounds from the water, which reduces algae growth and keeps the tank cleaner. Fish waste provides all the nutrients the plant needs, so you will not have to fertilize.

Key Takeaways

  • Pothos roots go underwater while leaves stay above the water line, so position the plant at the tank edge or use a suction cup holder.
  • You can use a pothos cutting from another plant or buy a small rooted plant; cuttings root in water within one to two weeks.
  • Pothos grows fastest with moderate to bright indirect light, the same light your aquarium already receives.
  • The plant pulls nutrients from fish waste, so no fertilizer or soil is needed, though you can add liquid fertilizer if growth slows.
  • Trim the plant regularly to keep it from overgrowing the tank and to encourage bushier growth.

Where to position pothos so it stays in place

The most common setup is to rest the pothos stem on the back rim of the aquarium with roots dangling into the water. This works if your tank has a rim wide enough to hold the stem steady—most standard tanks do. The leaves hang outside the tank and the roots stay submerged, which is exactly what you want.

If your tank has no rim or you want a cleaner look, use a suction cup plant holder attached to the inside of the glass at the waterline. These are plastic clips that stick to the tank wall with suction cups and hold the stem in place while roots dangle below. You can find them at any aquarium store for a few dollars.

A third option is to tie the stem loosely to a piece of driftwood or a rock that sits at the tank edge, letting the roots trail into the water from there. This works well if you want the plant to look more natural as part of your aquascape.

Starting pothos from a cutting or a small plant

If you already have a pothos plant at home, cut a 4- to 6-inch section from a healthy stem using clean scissors. Remove the lower leaves so that at least 2 inches of bare stem will sit in the water—the roots will grow from these bare nodes. You can place the cutting directly into your aquarium and roots will develop within one to two weeks.

If you are buying pothos for the first time, look for a small rooted plant at a garden center or online. Choose one with green, firm stems and no brown or mushy spots. Rinse off any soil from the roots under tap water before placing it in the tank—soil clouds the water and can clog your filter.

You can also buy pothos that is already grown in water, sometimes sold as a "water plant" or "aquatic pothos." These are ready to go straight into your tank with no preparation needed.

Light and water conditions pothos needs

Pothos grows in moderate to bright indirect light, which means it does well in the same lighting your aquarium already has. If your tank sits near a window with natural light, that is ideal. If you use an aquarium light, most standard LED lights provide enough brightness for pothos to grow steadily.

The plant does not need special water conditions because it is not fully submerged—only the roots touch the water. Your fish tank water is fine as-is. The temperature does not matter much; pothos tolerates anything from 60 to 80 degrees Fahrenheit, so it will be comfortable in any tank that is comfortable for your fish.

Pothos is also very forgiving about water quality. It actually improves water quality by consuming nitrogen from fish waste, so the plant and fish help each other. If your tank is cycled and stable for fish, it is stable for pothos.

Feeding pothos without fertilizer or soil

Fish waste contains nitrogen, phosphorus, and potassium—the three nutrients plants need most. As long as you have fish in the tank and you feed them regularly, pothos will have everything it needs to grow. You do not have to add anything.

If your pothos grows slowly or the leaves look pale, you can add a liquid aquarium plant fertilizer once a week. Follow the bottle instructions for dosage; most are designed not to harm fish. However, most people find that pothos grows fine on fish waste alone, especially if you have several fish or feed generously.

Do not use soil-based fertilizers or pellets meant for potted plants—these can cloud your water or release too many nutrients at once. Stick to liquid fertilizers labeled for aquariums.

Trimming and managing pothos growth

Pothos grows quickly and will eventually cover the back of your tank if left alone. Trim it regularly to keep it under control and to encourage bushier growth. Cut the stem just above a leaf node—the small bump on the stem where a leaf grows. New stems will sprout from below the cut, making the plant fuller.

Trim every two to four weeks, or whenever the plant reaches the length you want. You can compost the trimmings or propagate them in water to start new plants. Pothos is nearly impossible to kill through trimming, so do not be afraid to cut it back hard if it gets out of hand.

If roots grow too long and thick, they can clog your filter intake. Trim the roots back to 2 to 3 inches below the waterline every few months. This also encourages the plant to grow new, fresher roots.

Common problems and how to fix them

If pothos leaves turn yellow, the most common cause is too much light or inconsistent watering of the leaves above the tank. Pothos leaves should stay dry; if water splashes on them regularly, they can develop fungal spots. Make sure the leaves are in a dry area and the plant is not directly under a light that heats it.

If the plant stops growing or looks pale, it may not be getting enough light or nutrients. Move the tank closer to a window or add a plant fertilizer. If leaves are small and sparse, trim the plant back to encourage new, fuller growth.

Brown or mushy roots mean the roots are rotting, usually from poor water quality or a filter clogged by debris. Check that your filter is clean and your tank is not overstocked. Trim away the brown roots and they will regrow healthy.

Pothos is not toxic to fish, but fish may nibble at the roots if they are bored or hungry. This is not usually a problem, but if it happens, move the plant higher so the roots are less accessible or add more hiding spots and food for the fish.

Frequently Asked Questions

Can pothos live completely underwater in an aquarium?

No. Pothos is a semi-aquatic plant, not a true aquatic plant. The leaves must stay above water to breathe and stay healthy. If you submerge the entire plant, the leaves will rot within days. Only the roots should be in the water.

How fast does pothos grow in an aquarium?

Pothos grows moderately fast in aquariums, usually adding 1 to 2 inches of new stem per week under good light and with fish waste as nutrients. Growth slows in low light or cold water. You will likely need to trim it every few weeks to keep it from overgrowing the tank.

Do I need a special aquarium light for pothos to grow?

No. Standard aquarium LED lights work fine for pothos. The plant is not demanding about light and will grow in moderate indirect light. If your tank already has a light for fish, that is enough for the plant.

Will pothos hurt my fish?

No. Pothos is safe for all fish. It is not toxic and does not release harmful chemicals. Some fish may nibble the roots out of curiosity, but this rarely causes serious damage to the plant or the fish.

What if my pothos gets too big?

Trim it back. Cut the stems above a leaf node and the plant will branch out and grow bushier instead of longer. You can trim as much as you want—pothos is very hard to kill through pruning. The trimmings can be rooted in water to start new plants.