Non-Aquatic Aquarium Plants: A Beginner's Buying Guide to Avoid Them

Many non-aquatic plants are sold as aquarium plants because they look good in the shop and are cheap to stock, but they slowly rot in a submerged environment and quietly wreck your planted tank. To avoid them when buying new plants for the aquarium, it is good to learn the visual differences between an aquatic plant and common non-aquatic plants that can only be grown emersed. To avoid purchasing non-aquatic plants, get familiar with reliable aquatic genera like Anubias, Cryptocoryne, and Java Fern and look for the Latin names for unfamiliar plants to confirm which category they fall in. Do not assume that just because the shop placed the plant in a fish tank that it is an aquatic plant. This article is for new aquarium hobbyists and it highlights many common non-aquatic plants that appear in aquarium shops and how to avoid them.

Quick answer:

• Many plant species sold as “aquarium plants” are really tropical houseplants or marsh plants that cannot survive long-term submerged; they sit there for weeks, then melt and rot.

• Many aquatic plants are sold in their emersed grown form. To truly know whether a species can be grown submerged long-term, you would need to check them out using their accurate Latin name.

• Non-aquatic plants generally feature rigid stems and thick, woody roots designed for soil, contrasting with true aquatic plants that have thin, flexible stems and softer roots.

• Common non-aquatic plants sold in the hobby include Alternanthera bettzickiana, Hemigraphis repanda, and Ophiopogon japonica, all of which eventually die and decay in the tank.

• As these fakes rot, they leak organic waste into the water, stressing fish, feeding algae and skewing water parameters in ways beginners often blame on “bad luck”.

• Your best defense: buy from planted-tank or aquascaping specialists, learn the emersed and submerged forms of common aquatic plants, and walk away from anything the shop cannot identify by Latin name.

Aquatic plants often have more finely divided leaves and very thin stems compared to terrestrial plants.

Why are non-aquatic plants sold as aquarium plants everywhere?

You walked into a fish store, saw a cool dark-purple bush with thick leaves sitting in a tank labelled “aquarium plant”, imagined it glowing under your light, and that was that. Three weeks later, the stems are soft, leaves are turning yellow and translucent, the base smells a bit like swamp, and your pristine glass now has a fresh coat of green algae. The shop shrugged and said your water parameters are “probably off” and maybe you should buy more root tabs or look into CO2.

Here is the boring, unromantic fact: most general fish shops are not planted-tank labs; they are inventory warehouses. They source plants from big nurseries that mostly grow pond plants, bog plants, and landscaping foliage. In nature, these plants are happy with their roots wet but their leaves in air. Those nurseries are thrilled to sell a pot of shiny purple leaves that can sit underwater for a few weeks without dropping dead on day two. Many non-aquatic plants are sold as aquarium plants, causing confusion for hobbyists due to their appealing appearance and lower price. Everyone in the chain gets paid. Your aquarium is the one that gets to quietly rot.

The solution is not to “get a hardier fish” or “do daily 80 percent water changes until it stops melting.” None of these will save a non-aquatic plant.

Non of the species labeled above are aquatic. They look natural sitting in a planted tank, and some even look similar to true aquatic plants, but none of them will survive being submerged permanently.

How do you choose safe aquarium plants and avoid non-aquatic species?

• Learn a short list of both heroes and villains. Trim your wish list down to a core set of safe aquatic species for beginners. Reach for known aquatic genera like Rotala, Ludwigia, Echinodorus, Microsorum, Anubias and Cryptocoryne species. These groups are reliable true aquatic or amphibious plants with proven submerged growth, so you are not playing roulette with your tank every time you buy something green. Memorise a few common non-aquatic troublemakers; we provide several common offenders on this page. Once you have seen their shape and leaf structure, you will not fall for them again.

• Assume “display tank proof” means nothing. Stay away from the assumption that “if it is in their tank, it must be aquatic.” Many non-aquatic plants can survive submerged for weeks or months before they melt. Shops rely on that window to make them look convincing; your goal is to ignore the glass box sales tactic and rely on species knowledge instead.

• Aquatic plants are sold in both emersed forms and submerged forms. For many species, the differences between the two forms can be dramatic. It is useful to learn how to spot submerged growth forms.

Dracenia species are common houseplants, but they do not belong in an aquarium.

Selaginella willdenowii grows well in moist soils, however, it cannot be grown submerged long term.

Hemigraphis colorata (Purple waffle plant) has attractive purplish leaves but cannot grow well long term underwater.

Ophiopogon japonica looks like it will make for a good bush in the aquarium. However, it is not aquatic.

The flower stalk of Cyperus haspans is often sold tied onto wood. It looks like an Eriocaulon but is actually a nonaquatic plant. This portion is merely the flower head - the full-size Cyperus plant is a couple of feet tall.

Hemigraphis repanda (left) , also known as 'dragon's tongue', is another common nonaquatic. It has attractively shaped leaves with a purple underside. It looks very similar to the aquatic plant Hygrophila pinnatifida (right). It has shallower, narrow lobes and is generally much thinner than Hygrophila pinnatifida.

There are many aquatic Alternanthera species. However, Alternanthera bettzickiana cannot grow well submerged long term. It has attractive hooked-shaped leaves. In aquariums, the plant can last a few weeks but will weaken and rot eventually.

The picture above shows Alternanthera sessilis (left) beside Ludwigia glandulosa (right). Ludwigia glandulosa is an actual aquatic plant that can grow well long term in the aquarium. A. sessilis can be differentiated by its more rounded leaf tip compared to L. glandulosa. Ludwigia glandulosa has an alternate leaf arrangement, while A. sessilis has an opposite leaf arrangement.

How do you visually tell submerged growth from emersed growth when looking at new plants?

Your eyes can tell a lot. The majority of true aquarium plants used in planted tanks are either fully aquatic or amphibious species from marshes that can genuinely switch between emersed growth and submerged growth; the fakes cannot. Submerged growth contains adaptations that allow the plant to survive long-term underwater, and is a good indication that the plant is an aquatic species.

Here is the pattern you are looking for when looking for submerged growth forms :

• Foliage: Thin, soft, finely divided leaves that go limp when lifted out of water. Leaves lose their waxy cuticle and can absorb nutrients from the water more easily. The increased surface area of finely divided leaves allows better gaseous exchange under water.

• Stems: Flexible stems that are soft and bend easily. With water to support the plant's weight, submerged forms rarely waste energy reinforcing their internal structures to hold the plant upright.

• Roots: Submerged form roots tend to be softer and non-woody.

• Coloration: Many submerged forms are different in colored to their emersed versions.

Water wisteria has broader green leaves when grown emersed (left). Its submerged form has more divided leaves (right).

Rotala H'ra has round leaves in its emersed form (left) and thinner leaves that are yellowish or red in its submerged form (right).

Rotala rotundifolia Green has round green leaves in its emersed form (left) and thinner green leaves and stems in its submerged form (right).

Alternanthera reineckii 'rosaefolia' has reddish leaves when grown submerged (right). It has mostly green leaves when grown emersed (left).

Ludwigia repens has reddish/orange tones when grown submerged (right). The emersed-grown plants are largely green in color (left).

Ludwigia Super red can be green or red when grown emersed. Under less light the leaves are more greenish when grown emersed (left). The leaves grow very easily red submerged though(right).

Some additional popular aquatic plant names:

Is your algae problem actually caused by a rotting non-aquatic plants rather than poor water parameters?

Non-aquatic plants can often last for weeks or months in an aquarium before deteriorating, which can lead to algae problems as they decay. Acknowledge that deterioration is not sudden; the drowning plant can still produce new leaves from its stored energy reserves, creating an illusion of growth. Sometimes, the plant will make a last stand by sending up new stems that race for the surface, trying to grow leaves that can hit open air above the water line. These stems are often thin and leggy. They are not real healthy growth; they are the plant spending the last of its energy budget on an escape attempt.

As the plant drowns, it releases ammonia and other waste proteins as it decays. Nitrate and phosphorus levels spike, triggering algal blooms. Left alone, the remains of the plant can clog the filter intake, foul the substrate and significantly increase the organic load in the aquarium.

Remove, water change, then restock with true aquatics if you are already in trouble. If you realise that a plant in your aquarium is non-aquatic, do not hang on to hope. Take it out, siphon any mushy leaves and rotting roots from the substrate, do one or two large water changes to export the waste, clean the filter if it is packed with debris, then replace that space with hardy, proven aquarium plants that can actually thrive submerged.