Benefits of Floating Plants in Aquariums

Floating plants divide aquascapers: some see a nuisance that blocks light, others rely on them as the fastest, cheapest way to fight algae and keep fish calm. Both are right, and the difference is entirely about choosing the species and keeping them under control.

What Floating Plants Actually Do for the Tank

Because their leaves sit at the surface with direct access to air, floating plants grow fast, and fast growth means they strip ammonia and nitrate out of the water quickly. That makes them one of the best tools against algae, which competes for the same nutrients. Their trailing roots also give shrimp and fish fry a place to hide and feed, and the surface shade lowers the light hitting a new tank, which is exactly when algae tends to take hold. For labyrinth fish such as bettas and gouramis, a covered surface also mimics the still, shaded water they build bubble nests in.

The Ones Worth Keeping, and the One to Avoid

Amazon frogbit and dwarf water lettuce are the classic choices: large, easy to scoop out, with pretty dangling roots. Red root floater rewards strong light with red foliage. Salvinia forms a neat low mat. The species to think twice about is duckweed, which is tiny, breeds explosively, and is almost impossible to remove once it gets into a tank, often arriving as a hitchhiker on other plants.

Keeping Them Under Control

The same fast growth that helps you can take over the surface and starve the plants below of light. Scoop out a handful whenever the cover passes roughly half the surface, and keep them away from the outflow with a floating ring or a length of airline, since most floaters hate having water splashed on their leaves. A little surface movement is fine, a constant spray rots them.

The Bottom Line

Use frogbit or water lettuce as living algae control in a new or high-light tank, enjoy the shelter they give fry and shrimp, and thin them regularly so they never shade out the scape. Just keep duckweed out.