Monstera can grow in aquariums, but only the roots stay submerged
A Monstera (also called Swiss cheese plant) can live partially in an aquarium, with its roots in the water and its stems and leaves above the surface. The plant does not grow fully underwater — the leaves must stay dry and exposed to air. What you are creating is a semi-aquatic setup where the Monstera acts as a natural filter while the fish benefit from the plant's root system breaking down waste.
This works because Monstera roots are naturally adapted to humid, wet environments. In the wild, they climb trees in tropical rainforests where roots often dangle through mist and moisture. An aquarium provides that constant moisture without drowning the plant, as long as the leaves remain above water.
Key Takeaways
- Monstera roots can stay submerged in aquarium water, but the leaves and stems must remain above the surface and dry.
- You need a tank at least 20 gallons with a sturdy support structure, because a mature Monstera stem becomes heavy and will pull down flimsy setups.
- The plant will grow slower in an aquarium than in soil because it receives fewer nutrients, though fish waste provides some fertilizer.
- Trim the Monstera regularly to prevent it from outgrowing the tank and shading the fish, and remove any leaves that fall into the water.
Setting up the tank structure and support
Start with a tank at least 20 gallons. Smaller tanks heat up and cool down too quickly, and they do not leave enough room for both fish and a growing plant. The Monstera will need something to climb or lean against — a piece of driftwood, a moss pole, or a sturdy branch anchored inside the tank works well. Make sure whatever you use is stable and will not tip when the plant grows heavier.
Position the support so that the Monstera stem can rest against it while the leaves extend above the tank rim. You can run the stem over the edge of the tank and let it trail down the outside, or angle it so the leaves point upward inside the tank but stay above the waterline. The key is keeping the foliage dry. If leaves sit in water or are constantly splashed, they will rot.
Some people use a piece of rigid tubing or a PVC pipe fitted to the tank edge to guide the stem upward and out. Others straightforward drape the stem over the rim and find it loosely with a plant clip. The setup does not need to be permanent — you can adjust it as the plant grows.
Planting the roots in the aquarium
You can start with a Monstera cutting or a small potted plant. If you are using a cutting, let it develop roots in water first — this takes two to four weeks. Once roots are at least an inch long, you can place the cutting directly into the aquarium. If you are using a potted plant, gently rinse away the soil from the roots and place the bare roots into the tank water.
The roots do not need substrate (gravel or sand) to anchor them, though some people add a small amount of gravel around the base for stability. The roots will eventually grow long and spread through the water column. Fish will not eat healthy Monstera roots, though they may nibble at any algae that grows on them.
Position the roots so they are fully submerged and the stem exits the tank cleanly. Avoid bending or kinking the stem where it enters the water — a sharp bend can restrict water flow inside the plant and cause the upper leaves to wilt.
Water conditions and tank maintenance
Monstera roots tolerate the same water conditions as most aquarium fish. They do not require special pH, hardness, or temperature — whatever keeps your fish healthy will keep the plant roots healthy. The plant actually benefits from the nitrogen and phosphorus in fish waste, which acts as a slow fertilizer.
Change the water on your normal schedule. Monstera roots do not change how often you should perform water changes — you are still maintaining the tank for the fish first. If you notice algae growing heavily on the roots or stem, increase water changes slightly or reduce lighting hours, since algae thrives under bright light.
Do not use aquarium plant fertilizers unless you are keeping only the Monstera and no fish. Fish waste usually provides enough nutrients. If the plant's new leaves come in small or pale, that can signal low nitrogen, but this is rare in established tanks with fish.
Light and humidity for the leaves
The leaves above the water need bright, indirect light — the same light you would give a Monstera on a shelf. Aquarium lights alone are not bright enough for the foliage. Position the tank near a window with filtered sunlight, or place a grow light above the leaves. Six to eight hours of light per day is sufficient.
The leaves will stay naturally humid because they are growing over a water source, but they should not be wet. If you mist the leaves, do it in the morning so they dry before evening. Wet leaves in low light can develop fungal spots.
The Monstera will grow more slowly than it would in soil, because it is drawing nutrients only from fish waste and the minerals in tap water. Expect slower leaf development and smaller leaves than you would see on a plant in potting soil. This is normal and not a sign of failure.
Pruning and managing growth
Trim the Monstera regularly to keep it from shading the fish or outgrowing the tank. Pinch off new growth at the top to encourage the plant to branch sideways instead of growing tall. Remove any leaves that fall into the water when ready — decaying leaves foul the water and feed algae.
As the plant grows, it will develop aerial roots (small root-like structures along the stem). These are normal and harmless. You can let them dangle into the water or trim them off if they look messy. The plant will not suffer either way.
If the stem becomes too long or heavy, you can cut it back and propagate the cutting in water or soil. A Monstera cutting placed in the same tank will root and grow alongside the original plant, creating a fuller look.
Fish compatibility and safety
Most aquarium fish ignore Monstera roots and leaves. Goldfish and plecos may nibble at soft plant material, so avoid these species if you want the plant to stay pristine. Cichlids sometimes uproot plants, but since the Monstera roots are not anchored in substrate, they usually leave it alone.
The plant itself is not toxic to fish. However, if a leaf falls into the water and decays, the decomposition can spike ammonia and harm sensitive fish. This is why removing fallen leaves quickly matters — not because the plant is poisonous, but because dead plant matter degrades water quality.
Frequently Asked Questions
Can I fully submerge a Monstera in an aquarium?
No. Monstera leaves will rot if kept underwater. The plant evolved to climb trees with its roots in moist air and soil, not fully submerged. Only the roots can stay in water; the leaves must stay above the surface and dry.
How long does it take for a Monstera cutting to root in an aquarium?
Roots usually appear within two to four weeks if you start with a healthy cutting that has at least one node (the small bump where leaves attach). Once roots are visible, you can move the cutting into the aquarium. Growth slows in cooler water, so warmer tanks (72–78°F) root faster.
Will the Monstera harm my fish?
The plant itself is not toxic to fish. The main risk is fallen leaves decaying in the water and degrading water quality. Remove any leaves that drop into the tank right away to keep the water clean.
What size tank do I need for a Monstera?
Start with at least 20 gallons. Smaller tanks do not hold temperature well and leave little room for both fish and a growing plant. A 20-gallon long tank gives you enough space to position the plant support and let the Monstera grow without crowding the fish.
Can I use regular aquarium fertilizer on the leaves?
You can, but it is usually not necessary. Fish waste provides enough nutrients for slow, steady growth. If you add fertilizer, use it sparingly and only on the leaves above water — do not add it to the tank water, as it can spike nutrient levels and cause algae blooms.