Yes, you can absolutely grow Pothos, botanically known as Epipremnum aureum, in a fish tank. This popular, resilient houseplant is commonly called Devil’s Ivy due to its hardiness and rapid growth. Placing its roots in aquarium water is a highly effective, natural filtration method, often referred to as a simple form of hydroponics or aquaponics. The practice is widely adopted by hobbyists seeking to improve water quality and reduce routine maintenance.
The Mechanism: Pothos as a Water Purifier
The primary benefit of introducing Pothos roots to an aquarium is the plant’s significant role in nutrient export. Fish waste, uneaten food, and decaying matter continuously produce ammonia, which beneficial bacteria in the filter quickly convert into nitrites, and then into nitrates. While ammonia and nitrite are highly toxic to fish, nitrate is less harmful but still accumulates to dangerous concentrations over time, necessitating regular water changes.
Pothos acts as a powerful biological filter by absorbing these dissolved nitrogen compounds directly from the water column for its growth. The plant is particularly effective at consuming nitrate, the final product, which is a readily available nutrient. Some research also suggests Pothos roots can directly uptake ammonium, the preferred nitrogen source for many plants, effectively short-circuiting the entire nitrogen cycle before toxic compounds can accumulate.
By rapidly consuming these excess nutrients, Pothos helps maintain stable water parameters and can significantly decrease the frequency of large water changes required. The vigorous growth rate of the plant, especially when provided with strong light, directly correlates to its capacity for nutrient removal.
Setting Up Your Pothos Hydroponically
To successfully integrate Pothos into your aquarium, you must start with a healthy cutting that includes at least one node, which is the small bump or joint on the stem where the leaf and aerial root emerge and where new water roots will sprout. Using a clean, sharp tool, cut the vine just below a node, ensuring the cutting has a few leaves remaining above the cut point.
The most important preparation step is thoroughly cleaning the cutting to prevent introducing contaminants to the tank. If the plant was previously grown in soil, you must remove every trace of dirt, fertilizer, and any potential systemic pesticides by rinsing the roots meticulously under running water. Residue from commercial fertilizers or pesticides can leach into the aquarium and be fatal to fish and invertebrates.
Once cleaned, the cutting must be positioned so that only the stem and the node are submerged in the water, with all leaves remaining completely dry outside the tank. You can secure the cutting by tucking the stem into a hang-on-back filter compartment or by using specialized clips to hook the vine over the tank rim. This positioning allows the developing roots to access the nutrient-rich water while the leaves absorb atmospheric carbon dioxide and light for photosynthesis.
Maintaining Safety in the Aquarium Environment
While Pothos is highly beneficial for water quality, it is important to be aware of the plant’s potential safety hazards. Pothos leaves and stems contain calcium oxalate crystals, which are microscopic, needle-shaped structures that serve as a defense mechanism for the plant. If a fish were to ingest a piece of a leaf that fell into the water, these crystals could cause immediate irritation and swelling in the mouth and digestive tract.
Fortunately, calcium oxalate is not highly soluble in water with a neutral or alkaline pH, which is typical for most home aquariums. This means the crystals are unlikely to dissolve and contaminate the water column simply by having the roots submerged. To minimize risk, you must ensure that no leaves are ever allowed to dip into or fall into the aquarium water, preventing any chance of ingestion by the fish.
It is crucial to source Pothos carefully, confirming it has not been recently treated with systemic pesticides, which are absorbed into the plant’s tissues and can leach into the water. Any leaves that turn yellow or die should be removed immediately. Rotting organic matter in the water will break down and contribute to the very nitrate buildup you are attempting to manage.