Water Lettuce and other floating plants for the tropical aquarium

Why use floating plants in the aquarium?

Floating plants are aquatic flowering plants and ferns that, as their name suggests, float! This makes them really useful additions to the aquarium or for ponds. Water Lettuce (Pistia stratiotes) is an example of such a plant species but there are very many more. In this hub I am going to be having a look at some of the most well known types and see how useful or not they are.

Floating plants provide hiding places and shelter for baby fish, places for fish to spawn, shade from too much overhead light and make the aquarium more interesting and far more like a natural habitat.

Water Lettuce

Water Lettuce (Pistia stratiotes)
Water Lettuce (Pistia stratiotes)

Water Lettuce

Water Lettuce is a plant I used to grow in all my aquaria and I had as many as 10 tanks at one point. I used to sell the surplus or trade it at the local tropical fish and aquarium shops. Water Lettuce is very easy to grow but only if you give it enough room for its leaves to grow upwards and not to get scorched by overhead lighting. This used to be a problem with many aquarium hoods that were not high enough above the water surface.

Water Lettuce is ideal for indoor pools in greenhouses and also for outside where the climate allows. It needs a subtropical temperature and cannot tolerate freezing conditions. Water Lettuce has spread on waterways all over the world in tropical and subtropical areas and is regarded as an invasive water weed.

In the tropical fish tank though it can be kept under control by removing the surplus. It has delicate roots that form bunches that trail down into the water. They make ideal spawning grounds for many egg-laying fish and also for newly-hatched babies to shelter in. Many species of fish enjoy resting amongst the toots of Water Lettuce too.

Water Lettuce reproduces by throwing out runners with baby plantlets on them. It needs a lot of light to do so. In some conditions the leaves will get a a couple of inches long and spring upwards or they will lie flat on the water surface in not so good conditions.

Water lettuce and guppies


Ceratophyllum submersum by Christian Fischer
Ceratophyllum submersum by Christian Fischer | Source


Hornwort (Ceratophyllum species) is the name of several species of aquatic plant that grow in temperate and tropical parts of the world. The Hornworts have delicate leaves that are like little green needles and are arranged in whirls around the equally delicate stems that can easily break. This is too the plant's advantage because it helps to spread it about.

Hornwort can also be grown anchored to the bottom but it does not produce roots and in my experience is best left floating. It will rapidly cover the surface of a tank and produces a layer of the plant to several inches deep. This is ideal for small fish and fry to hide out in.

The species that grow in cold-water will die back as winter approaches and produce vegetative buds that sink to the bottom and stay dormant until the spring brings renewed light and warmer water.

Floating Plants for your Aquarium

Indian Fern, Water Sprite or Floating Fern

Indian Fern (Ceratopteris thalictroides) is a true fern that has several different forms of the same plant. It can grow out of water in wet marshy conditions, either partially submerged or right out of the water, it can be a submerged plant that grows upwards from the substrate, or it can be a floating variety that reproduces itself with countless baby ferns on its leaf edges. These little ferns detach as they grow bigger and continue the cycle of growing larger and producing their own little ferns. This fern is also known as Water Sprite.

The floating variety of the Indian Fern is often sold, appropriately enough, as "Floating Fern." It is very easy to grow and will cover the surface of a tank with its delicate and attractive foliage. If fronds of it are broken they will not die but will produce baby ferns. It is another floating plant that I used to end up with a surplus of that I used to sell to the local tropical fish shops where I lived.

The floating form of Indian Fern has floating leaves that lie flat on the surface with their upper part exposed to the air if they are undisturbed.

Like all floating plants, Indian Fern makes a great place for baby fish to hide away. It is also popular with labyrinth fishes such as Siamese Fighting Fish and Gouramis that build bubble-nests. They will often choose to do so under a floating frond of Floating Fern.

Salvinia natans

Salvinia minima by Kurt Stüber
Salvinia minima by Kurt Stüber | Source


Salvinia natans is one of the most commonly distributed ferns in the Salvinia family in which there are over a dozen species. It is also sold as "Floating Fern", "Floating Moss" and "water Butterfly Wings."  It grows wild on waterways, ponds and lakes throughout the world in many tropical and subtropical parts. 

Giant Salvinia (S. molesta ) is, as its name suggests, a much bigger variety of Salvinia. 

Salvinias are true floating ferns and have flat floating leaves and creeping stems that rapidly will forms mats or cover the surface of an aquarium or standing water in a natural habitat.  Like so many floating plants they are regarded as invasive weeds that cause serious problems in waterways but in the tropical fish tank they make an interesting and attractive addition.

Because they have no roots or foliage hanging down below the surface they do not provide any cover for baby fish so are of little use for such purposes but they do help make an aquarium more like a natural habitat and this helps keep fish happy. 

Water Hyacinth

Water Hyacinth
Water Hyacinth

Water Hyacinth and other floating plants

Water Hyacinth (Eichhornia crassipes) is a much larger floating plant than the other species described. It has shiny leaves carried on stems with inflated spongy floats in them and bears spikes of pretty purplish-pink flowers that give the plant its name. Water Hyacinth reproduces by runners and offsets all around it and rapidly will cover a pond, lake, canal or other waterway. It is found in subtropical and tropical areas around the world and like many other floating plants is regarded as a problem and an invasive weed.

In the tropical fish tank it is not of much use either unless the aquarium is very large and has no hood because the Water Hyacinth needs plenty of room above the water for its leaves and flowers. It is great in indoor pools though in greenhouses or outside where the climate is warm enough.

Water Hyacinth has very dense and dark- purplish-black-coloured roots that form think bunches beneath each rosette. The roots are ideal for may egg-laying fish to spawn in and for the fry to hide in after hatching.

There are many more floating plants that are sold in the aquarium trade. Amazon Frogbit (Limnobium laevigatum) is an attractive plant with rounded leaves that are similar in shape to the European Frogbit (Hydrocharis morsus-ranae). However, coming from South America it grows well in the tropical fish tank.

Two very small floating plants that are best avoided are the Azolla species that are known as "Fairy Moss" and "Water Velvet" and the equally tiny Duckweeds (Lemna species). Attractive as they are these little plants will clog aquarium filters and serve nor real purpose in a tank set-up. Azolla will grow so thickly on the surface of ponds and canals that it looks like land.

There are many more floating plants that can be used in the tropical fish tank but I have tried to cover some of the main ones you will see for sale.

The disadvantages of floating plants are that they block light levels and can grow so fast you will need to control them., however, their advantages are many more. All floating plants help keep your fish more content and make great spawning sites for many species. They are also great places for baby fish and bullied fish to hide away.

Copyright © 2011 Steve Andrews. All Rights Reserved.

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Comments 8 comments

carol3san profile image

carol3san 4 years ago from Hollywood Florida

Hello there. This is a wonderful hub. I can tell that you put a lot of work into it. I voted you up, useful, and interesting.

Bard of Ely profile image

Bard of Ely 4 years ago from Lisbon, Portugal Author

Thank you! Much appreciated!

homesteadbound profile image

homesteadbound 4 years ago from Texas

You did a lot of research to put this information together. I tried to introduce something called duckweed to my outdoor pond, but the koi demolished it immediately. They loved it.

Bard of Ely profile image

Bard of Ely 4 years ago from Lisbon, Portugal Author

I didn't really. Most of it I already knew! Thanks for posting!

nenytridiana profile image

nenytridiana 4 years ago from Probolinggo - Jawa Timur - Indonesia

It took experiences to write like this. Great, Bard of Ely!

Bard of Ely profile image

Bard of Ely 4 years ago from Lisbon, Portugal Author

Thank you, nenytridiana! I have plenty more!

jesusmyjoy profile image

jesusmyjoy 4 years ago from Bucyrus Ohio

amazing information

Bard of Ely profile image

Bard of Ely 4 years ago from Lisbon, Portugal Author

Thank you!

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