Water Lettuce in Aquarium: Facts & Benefits

Water Lettuce in Aquarium

The water lettuce is a doubled sided aquarium plant. On one side, it can be quite ornamental and instrumental in the fight against algal bloom, but on the other hand, the plant itself can be just as dangerous as the algae you want to so desperately get rid of.

Left unchecked the water lettuce can be more of the problem than a solution, so what exactly makes this plant so special and why should you be wary of it?

The water lettuce or Pistia stratiotes is an aquatic plant that was initially discovered at the waters of the Nile. They originally come from Africa, and over the course of time, they have spread all over America and Europe.

They are especially popular in water gardens and open aquariums because of their beautiful rosette leaves and potency against algae; they also compete with other plants over nutrients.

Despite their beauty and usefulness, they have suffered a somewhat negative reputation. They are notoriously gifted at reproduction and they have been classified as weeds by several countries worldwide.

They float on the water surface with the help of their leaves and when left unchecked they can outgrow and cover up the entire water surface, eventually starving the other plants and fishes.

When grown and tended to properly, they can be quite instrumental in keeping things in order. They regulate the nitrate concentrations in the water and keep the fish alive and protected.

Dwarf Water Lettuce in Aquarium

Dwarf water lettuce is the more tolerable and manageable variant of the water lettuce. There have been speculations as to whether they are an established species on their own but the results are far from conclusive.

The popular belief is that they are a variation of the water lettuce that is triggered when the nodes are introduced into a more nutrient deficient environment. Most individuals prefer this to the more prevalent type of water lettuce.

This one, as it turns out, is considerably easy to look after and their roots don’t grow as much. they make fantastic ornaments without the added risk of unchecked growth and they perform all the functions normal water lettuce should.

Water lettuces can be quite a problem when they are left unchecked. They are a fantastic addition to the tank because they feed on nitrates, but are wild and oftentimes uncontrollable; however, they are not completely irredeemable.

They help the fish in ways you don’t even understand. They provide shade for the smaller fishes; they also soak in nitrates which could be potentially lethal to the fishes. Water lettuces are perennial plants that flower rarely and adapt well to semi-temperate regions.

In Florida, it’s illegal to own and house a water lettuce without the proper documentation and it’s punishable by a steep fine.

They are considered dangerous because of just how well they spread with little to no other nutrients apart from nitrates. They are considered a public nuisance in this state and are dealt with using every means in the book.

Herbicides, beetles, larvae, and mechanical removal have been used in the past to rid public ponds and larger bodies of water of these atrocious plants but the question is, does the good outweigh the bad?

Do the many advantages of this insanely invasive plant more than make up for the potential troubles it will definitely stir up? quite frankly, no.

The plant might be useful and powerful enough to keep the algae at bay, but if you are able to get your hands on the dwarf plant of the water lettuce, then it would be in your best interest to go with the plant that is infinitely easier to control and maintain.

Facts about the Water Lettuce

The water lettuce is a tropical plant

The water lettuce was found in Africa; this means that the plant might be only able to grow and flourish in more temperate environments.

Like a great deal of tropical marine and plant life, the water lettuce is dependent on the temperature of locations close to the equator.

This means that this plant can’t grow in just any temperature, it prefers warmer, more temperate waters, and this usually translates to a tropical tank setup.

The water lettuce is a tropical plant and this means that it needs a lot of light and heat.  The water needs to be around 60 degrees and the surface temperature needs to range from 70 to 80 degrees Fahrenheit and these numbers have to be constant.

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It will not survive most winters

The plant cannot deal with the cold, one little bit. It withers and dies almost immediately and it’s almost impossible to keep it alive during winters.

Despite most attempts to keep it healthy and alive during cold winter months, it ends up withering halfway through winter. In my experience, transferring it to a more temperate or warm room is bound to extend its life span considerably but ultimately it is futile. They almost always never make it through those cold months.

They do not require a soil

As they grow, they have wispy roots that extend from the plants and sometimes grow up to an inch or two into the water. the water lettuce roots are its main source of sustenance and they can go their entire life without needing as much as a grain of sand or soil.

Their leaves are unique

The water lettuce leaves are more peculiar than most. It has a unique rosette pattern that is truly aesthetic. The leaves area pale and yellow-green and are fan-shaped and adjoining like ribs.

The leaf surface is covered in fine hairs that were designed to retain water and increase the overall buoyancy of the plant on any given water surface. The leaves of the lettuce are more intricately adjoined towards the plant’s root and they form a dense mat over the water surface eventually.

The leaves of a fully matured lettuce can reach up to six inches and the hairs of the plant can get less dense as you move closer to the center of the plant.

water lettuce


One of the funniest things about this water plant is that it actually has nothing to do with actual lettuces. They are called water lettuces because they look a lot like actual lettuce.

The first few days are always a struggle when trying to introduce these guys to a tropical aquarium setup. they usually struggle for a bit and try to acclimate themselves with the tank water and when they eventually do, it takes a minute or two for them to get growing really. This can be somewhat problematic at first, but when they really get going there is no stopping them.

Water lettuces reproduce in one of two ways; Asexually and sexually.

When the water lettuce reproduces asexually, then, it reproduces in a mother-daughter fashion. A new plant is born and but still attached to the old one by a stolon.

The stolon usually sticks out of place and when the replication process has repeated itself an absurd number of times, the plants eventually form a dense mat that is fast and strong enough to cover the entire surface of relatively large bodies of waters in a short time.

Asexual reproduction is the main way that the plant reproduces. The sexual way is also possible, but very unlikely; it only happens in rare situations.

The sexual method deals largely with cross-pollination. The male flower and female flowers usually belong to separate plants and when they somehow manage to reach one another and cause fertilization, a small greenish seed is produced. This begins the life of a new plant and eventually a new mat.

The seeds of the water lettuce usually eventually change from a green to brown when it ripens. Sexual pollination is more likely in dense mats and the wind is usually the agent of pollination in instances like these.

The seed of the plants usually float on the water surface for a relatively short time then eventually sink and reemerge after a few days of waiting. They will resurface as far as the water is not too cold; they are surprisingly resilient once they are well dug in.

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Are water lettuce poisonous

It depends on who you ask. If you ask the devout aquarium enthusiast, he might give you a clear answer like no; which is technically the truth but that is if you are a hobbyist.

The government, however, classify the plant as dangerous and potentially harmful to all life. This is a bit hefty considering the plant is just aquatic and in no way actually poisonous.

The sites where they are found usually come with a caution sign to ward off all interested parties and it has been listed amongst the country’s list of noxious plants.  Water lettuce is edible to some species of fish and cattle seem to stomach them fine, so why were they classified as dangerous and why does the government hate them so much.

Why the government hates water lettuces

When water lettuces start growing healthily in a particular location, they tend to choke every other plant out. they will compete over the resources and eventually cause other plants to wither.

They greatly reduce light penetration, reduce oxygen concentration and mess up the pH of the large water bodies like communal ponds.

They are the harbingers of disease. Malaria-carrying mosquitoes have been known to frequently appear in areas and bodies of waters that have been overrun with water lettuce.

Uses of the Water Lettuce

This is a great question? Given the never-ending list of reasons why you shouldn’t attempt to cultivate or add this plant to your aquarium, there are some fairly acceptable reasons.

They aren’t just wild weeds that are impossible to control, on the contrary, a lot of aquarium hobbyist have succeeded in cultivating and controlling this unruly plant.

They have weighed their options and decided to deal with the challenges that come with this dominant plant. Some of the uses are;

They are ornamental

Never underestimate the beauty of this weirdly shaped plant. It is beautiful and makes a memorable addition to the surface of the aquarium.

They are edible

As I said, they have become past time meals for the herbivores of the tank. , in particular, have been known to give a strong appetite for the plant and have been known to kill them off entirely when they are still young.

They reduce the probability for an algal bloom

Algae is probably the most disturbing and irritating plant life that you can house in your aquarium. Left unchecked, they can really be a problem. One of the best ways to stop them in their tracks is by adding other plants to the aquarium, and one of such plants is the water lettuce.

They have been known to considerably limit algal blooms in numerous tanks and this might be one of the reasons that they are one of the preferred methods to prevent algae despite the obvious risks involved.

It can be used to keep the water pure. This little advantage might be unknown to most aquarium owners, but it might just be the greatest and noticeable advantage of the plant.

It has the ability to clear out mercury from water by absorbing them. they can deal with a fair amount of mercury but are hopeless when the concentrations are too high.

States that prohibit the sale and transportation of the water lettuce

Although it has garnered a lot of attention and appreciation amongst some circles, it still remains a weed and a source of concern in others.

In certain states in America, they still remain a threat to marine life and are categorized as noxious weeds. They spread like a wildfire once they have properly dug in and they are quite difficult to eradicate because of their volume.

How to deal a water lettuce infestation

Water lettuces can be quite the nuisance when they are left to themselves. Usually, there are a handful of different ways to deal with them, the first being letting nature take its course.

However, this is problematic because it’s not an option in more temperate regions. They are simply not cold enough to kill them during the winter months.

Over the years, people have devised more practical and effective ways to deal with the plant without having to depend on the ever-changing seasons.

The use of different well-known insects in their complete annihilation has been popular in instances of mass scale infestation. The Neodydronomous pulchellus weevil has been used as a biological agent of containing the spread of the plant.

Another insect that is particularly known for its palette for the otherwise inedible plant is the Spodoptera pectinicornis. It’s a caterpillar that is native to Thailand and it has been used by several state authorities and other concerned third parties to curb the spread of the plant.

The use of well-known herbicides like Shoreline defense is also an alternative to the weevil solution. They are more effective but ultimately detrimental to the aquarium residents.

They are more effective against infections in large bodies of waters like ponds, however, using them in a more enclosed body of water will no doubt put both the plants and the fish in danger.

There is also the classic, all-natural weeding. It has proven to be the most effective method when trying to control them in an aquarium setup and they tend not to completely eliminate the plant from the aquarium. This way you keep the number of lettuces that you are comfortable with and not endanger your fish.

Planting the water lettuce

Although it’s true that the water lettuce tends to hog all the nutrients for itself, it’s possible for them to exist in association with other aquatic plants. They can go a long way to improve the overall aesthetic of the entire tank.

When trying to add the water lettuce to your tank, there are some rules to follow to make sure that they survive the initial introduction to the foreign tank.

They are not quite as resilient as they are made out to be. In most cases, they rarely survive without some help from the outside.

They need a little sunshine

Like all plants, they need sunlight for photosynthesis. Cultivated water lettuces, however, need sunlight introduced to them in levels.  They have to be gently introduced to sunlight.

They might burn and perish if they are just introduced to direct sunlight immediately. An artificial light source or shaded exposure is recommended. A couple of T5 or T8 bulbs should be just fine in the first few weeks.

You need to watch the humidity

Water lettuces are particular about their humidity, they need lots of it to grow naturally and healthily. If the room is particularly lacking humidity, you could consider covering the tank.

That will provide enough humidity to keep the plants growing strong.  I know that this might not be the best for a planted tank, but the cover-up will only last a few weeks.

Tips for keeping water lettuce from overtaking the tank

Although they can provide some form of shade for the smaller fish, they can quickly become a nuisance because of their speedy reproduction. The only way to prevent this eventuality is to do a little weeding every week or so.

They might not look like they need it, but all it takes is a few days and they’ll completely overrun the tank. Cutting a few stolons off every week is enough to keep them at check for now.

If you are looking to get rid of them all, then wait patiently till the winter. The weather is considerably colder and they will die out in the first month or so.


Saurabh Kumar

I am a passionate fish keeper, with years of experience. You will find some really useful tips and information on this blog about Freshwater Aquariums.

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