Planted fish tanks are some of our favorite things here at Vivofish. Water lettuce, water wisteria, water iris, duckweed, hornwort – we love them all!
We love the way good plants give fish shelter, help clean the water in the fish tank, keep fish and other critters happy, and more. But the question is always “which plants” should we keep?
One of the freshwater aquarium plants loved by many fishkeepers is water lettuce. So, we’ll take a look at how to care for that plant and how to better understand it.
Quick Overview Facts on Water Lettuce
Water lettuce is a perennial evergreen that forms in large floating colonies. It has foliage that is a light green and grows between one to six inches long.
Its roots have a floating system that can grow upwards of twenty inches in length and the plant itself grows in a three by twelve-foot area.
If the colonies of the plant are not properly tended to they can become invasive.
Due to this plant’s invasive nature, some states and countries have made it illegal to own or transport this plant. If you are interested in using it, make sure to check to make sure there are no restrictions where you live.
This plant’s name comes from its rosettes which look like small heads of lettuce. There are a number of smaller of fish who like to use its dangling root system as a place to hide.
During late summer and up until the early winter it has yellow flowers that will bloom.
Author note: While this plant is popular in aquariums it can be difficult to grow. With the right elements it is possible to grow them until they create a great place for fish to use.
| Scientific Name | Pistia stratiotes |
| Genus | Pista |
| Other Names | Water cabbage, or Nile cabbage |
| Lighting Needs | Medium |
| Growth Rate | Fast |
| Temperature Requirements | Above 60 degrees Fahrenheit |
| pH Level | 6.5-7.2 pH |
| KH | 5-20 |
| Care Level | Moderate |
| Minimum Tank Size | A tank large enough to hold a plant with 20-inch roots |
| Maximum Plant Size | Can grow into a patch of 3×12 feet |
About Water Lettuce
This plant originated in the Nile River, presumably around Lake Victoria in Africa. Water lettuce is a plant that floats on the surface water. Its leaves form a rosette and have dense roots that grow deep into the water.
While this plant is notorious for growing like a garden weed in the wild, it can be difficult to get it to grow in your fish tank.
One of the biggest reasons this plant struggle to grow is a lack of indoor humidity, sometimes adding a cover to the aquarium is enough to fix this.
On the other hand, when provided with the right conditions, it is very easy for them to overrun an aquarium. When this plant begins to grow it is a good idea to remove a few plants during your weekly tank maintenance.
About the Types of Water Lettuce
Ruffled Water Lettuce – this variation has leaves that are wavier and does not grow as large or rapidly as other varieties. If you are wanting to put water cabbage into a small container, this is a great choice.
Jurassic Water Lettuce – this is a large variety of this plant that can reach the size of a dinner plate. This does not grow at the same speed at the more common varieties.
Splash Water Lettuce – is a form of water lettuce that stays small and can be difficult to find for your aquarium.
Uses and Benefits for the aquarium
For many parts of the world, this plant is seen as a pesky weed that grows so fast that it kills other plant life. These same places discourage or have made it outright illegal to own and grow the plant.
In some places, this plant has grown so out of control that it has blocked lakes, waterways, and canals. These blocked waterways hinder boats and other water transportation.
However, despite the negative of this plant, there are some benefits to using this lovely plant.
Author note: This plant can help control the spreading of algal bloom in the water. Generally, algae have to be controlled by a variety of means, especially when trying to keep it out of water gardens and backyard ponds.
Instead of a complicated solution, just try growing water lettuce.
Part of the reason water lettuce grows so fast is that it tends to drain all of the available nutrients from the water it is growing in.
The downside of this means that if you are growing any other plants you will have to add some fertilizer to help them grow.
The upside of this plant being so greedy is that it ensures that your water does not have excess nutrients and it becomes that much easier to maintain balance in your water’s ecosystem.
The system of roots that Water Lettuce produces can be very attractive to fish who like to hide or want privacy for reproducing. These roots grow down and outward of up to twenty inches.
If the plant is taken care of and properly maintained then it can be aesthetically pleasing. The green of the foliage and its wide leaves can offer the right tank or pond another way of looking good.
The plant can also act to oxygenate the water. While most people would want to use an aerator to make sure there is a right balance of oxygen, have some natural sources of it doesn’t hurt.
Top tip: Water lettuce is a great plant for goldfish tanks and koi ponds, by the way, as it helps to draw these fish to the surface of the water.
Downsides of using it in Your Aquarium
Due to its ability to grow rapidly and kill other plant life, Water Lettuce has gotten a bad reputation.
For example, in Florida, it is illegal to own and house any of these plants unless you have proper permission and documentation. Those who are caught with the plant can be punished with a steep fine.
In Florida, this plant can grow so rapidly and create such a heavy overgrowth that it reduces surface air exchange and has been known to kill fish.
In the United States, this plant is also banned by the USDA in Alabama, California, Louisiana, Mississippi, South Carolina, Texas, and Wisconsin.
Countries that outright ban this plant include the U.K and New Zealand. The plant has heavy restrictions placed on it in both Japan and Australia.
Tank Requirements
Water Parameters
Water Lettuce is a tropical species and needs warm water to stay healthy and grow. The ideal water temperature range for this pant is between 70-80ºF.
However, it is possible to grow this plant in colder temperatures if the right precautions are taken.
This plant’s ideal PH range is 6.0-7.5.
If this plant is grown in an aquarium that lacks humidity, the tank needs to always remain covered.
Tank Size
For growing this plant it requires a minimum of ten gallons per planet. However, as this plant grows and spreads rapidly, it is important to conduct weekly trimming to make sure it doesn’t choke out any other life in your tank.
Fertilizer and CO2
Part of what has given this plant its reputation is the fact it can grow in water with just nitrates for nutrition. The only reason this plant should have any difficulty growing is if it needs nitrites added to the water.
Lighting
Lighting is important for plants but bright light will scorch the leaves of the plant. This is a plant that thrives in shaded areas. For growing at home a standard set of full-spectrum T8 or T5 bulbs should be enough for it to grow.
You can tell if the light is too harsh because the leaves of the plant will start yellowing, however, if it is not getting enough light the leaves will become stunted and grow small.
Basic Care Guide for Water Lettuce
While Water Lettuce should have no problem growing, it does require some attention to help it become established in an aquarium.
After it’s been set up and established it is vital that its growth is managed or you will end up with an aquarium overtaken by Water Lettuce.
If this plant is being grown in an environment with dry air, the leaves can easily dry out and become burned by bright light. You can try making the air around your aquarium more humid or try adding a cover to your aquarium.
When you first plant the Water Lettuce in your tank it is important to allow it a few days to acclimate. It will need lower light and time to adjust to the water chemistry of the tank.
Most Water Lettuce sold in nurseries tends to be grown in low light so it needs time before it can handle bright light without its leaves burning.
If your tank has any other aquatic plants, it is important to thin the Water Lettuce so that light can reach your other plants. If you do not keep up with your Water Lettuce it will kill the other life in your tank.
If your tank has a filter that causes a significant current, it’s important to have a floating dam to protect the water lettuce. Fast flowing water will disturb the plant and it will stop growing or become submerged and then die.
For an easy homemade dam, you can place suction cups on plastic tubing, and place them across a portion of the tank.
While Water Lettuce works with most fish, it’s important to make sure you do not place it with a tank that has large herbivore fish. The fish will attack the roots and eventually eat the plant itself.
Maintenance for Water Lettuce
Water Lettuce is an easy plant (like Anacharis) to take care of, so much so that if you aren’t paying attention it can overwhelm your tank. There are some things to keep in mind before your purchase, plant, and begin to care for.
Make sure it is legal to own Water Lettuce where you live. There are several countries and regions to have either banned or severally restrict ownership of this plant.
When you are purchasing Water Lettuce it is suggested that you should get a smaller plant. It only takes a few months for the plant to reach full size and start to spread, so you might as well save money by not buying a fully grown plant.
Sapling water lettuce needs to avoid full sun and moving water. These plants need shade, especially when they are first brought home.
You should not place these plants in a pond until they have had time to grow and adjust to their new environment. Otherwise, the plant may wither or get swept away.
When this plant is in ideal weather and grown conditions, it will begin to multiply and grow quickly. Depending on how fast this plant grows you may need to trim and uproot extra Water Lettuce once or twice a week.
When you remove Water Lettuce from your pond or aquarium, never dispose of it by throwing it into a natural body of water. There is a chance it will begin to rapidly grow and multiple and destroy the natural ecosystem.
It’s better to use the plant in composting or by throwing it in the trash.
When you change the water it is important to not drastically change the water type.
When you are going to change the water type it is best to remove the plant from the water and place it in a container of the new water for a day a two and then reintroduce them into the garden after the water has been changed.
Common Problems with Water Lettuce
When it’s in prime condition, Water Lettuce can easily become a menace. However, several health problems can pop up to cause issues with its growth.
This plant is sensitive to direct sunlight. If it is placed in sunlight inside of the shade, the green leaves will become yellow leaves.
There has to be a balance of light for it to grow but not so much light that it saps away moisture and turns the leaves yellow.
If you are planting Water Lettuce outdoors and your garden or pond is in direct sunlight, you can provide shade by planting taller floating plants over it. Lilies are a great choice for this shade plant.
Indoors, it is possible for your artificial light to also scorch and kill Water Lettuce. It’s a great idea to use LED lights for having indoor lighting, just make sure it doesn’t generate too much heat or gives off too much light.
Another potential cause of Water Lettuce turning yellow is because the plan doesn’t have adequate nutrition. While the plant can survive like this for a while it is not ideal and can eventually lead to the plant dying.
This can be fixed by adding nutrient tablets and other supplements to the substrate that the lettuce is in.
Your Water Lettuce can cause damage to other Water Lettuce in the same pond or tank. You need to carefully monitor the growth and make sure to trim things so that leaves do not grow and cover up other leaves.
If you aren’t trimming your plants at least once a week it will not take long for the plants to start growing out of control.
You may have to take a more drastic measure of weeding out excess Water Lettuce plants so that your water doesn’t become overwhelmed.
How to Plant Water Lettuce
With the right approach, it is possible to have Water Lettuce share the water with other plants without the plants dying. With the right mix of plants in your tank or back yard pond, it can look great and be something to be proud of.
While Water Lettuce is resilient it still needs a careful touch when it comes to balancing their light and nutritional needs.
Without enough light the Water Lettuce can’t photosynthesis and then it will die.
Water Lettuce that you buy from a grower needs to be introduced to light in levels, a very gentle introduction to sunlight. During this process you can use a couple of T5 or T8 bulbs.
It is also important to make sure your Water Lettuce has access to humidity. While you can’t control this when it comes to planting in an outdoor pond, it is much easier to control the humidity with your inside tank.
Top tip: If your plant seems to need more humidity all you need to do is add a cover to your tank.
How to Trim Water Lettuce
It’s important to know how to trim Water Lettuce or you will end up with a pond or tank that is nothing but lettuce and everything else dead.
It can take as little as a week for Water Lettuce to start pushing out the other life in your tank. If you take the time to cut off some of the Water Lettuce once a week it can keep your plant in check.
If you are planting Water Lettuce outdoors, keep in mind winter weather will kill the plant off quickly.
It’s also important to not plant this in water that has plants that like to eat vegetation or the Water Lettuce will not last long.
When you are ready to trim your Water Lettuce, there are a couple of things that need to be done.
First, make sure to cut off several stolons or individual plants every week.
Next, make sure you cut the roots and leave only about four inches of their root system. If the roots are left to grow they can easily get entangled in filters or decorations.
How to Propagate Water Lettuce
While this plant may be called Water Lettuce, it is not a part of the lettuce family. It was called Water Lettuce because its leaves look very similar to lettuce, not because it goes well in a salad.
This plant is known to have some trouble adjusting when you first plant it and may take a little while to be ready for propagation.
It needs to have a lot of humidity and the perfect mix of light in the shade. After the plant has acclimated to where you want it to be, watch out because it will begin growing rapidly.
This plant reproduces asexually. When a new plant is born it is still attached to the old plant by a stolon. The stolon sticks out some from the plant.
When the reproduction process begins to speed up, the plant will eventually form a dense mat that is thick enough to quick all other life in a body of water.
While this plant can reproduce sexually with the pollen from other water plants, this is incredibly rare when you have them inside of a tank environment.
Top tip: Instead of waiting for pollination the plant will take matters into its own leafy hands and start growing other Water Lettuce plants in every direction.
Water lettuce FAQs
Is Water Lettuce Easy to Grow?
With the right tank and water parameters, Water Lettuce is an easy plant to take care of. It’s a flowing perennial plant used to grow in tropical or subtropical waters.
It needs to be in water warmer than 59F and does best in water temps between 72-86F.
As it grows, Water Lettuce will make small flowers in its center. Typically these blossom during the summer months up through the early part of autumn.
They are known to produce many seeds that can sink to the bottom of the water they are in and eventually may sprout and grow into more plants.
Is Water Lettuce a toxic or invasive species?
Water lettuce is a widespread pain native to many parts of the world. Due to how quickly it spreads, many countries now consider it a pest.
Due to its rapid growth, it can create significant economic hardships by blocking irrigation systems and causing damage to rice fields.
In addition, some places have had such significant infestations of Water Lettuce that it prevents boats from traveling and prevents fishing.
Another problem with Water Lettuce is its toxicity.
If it is eaten or consumed by pets or children, it can harm them. In addition, the plant contains calcium oxalate, which will burn the mouth and damage the kidneys.
