TankBud

Floating aquarium plants

Floating plants sit at the surface, shading the tank and soaking up nutrients that would otherwise feed algae. Each profile lists how fast a plant grows and the light it prefers.

At a glance

Height
0–39.4 in
0 in (0.1 cm) to 39.4 in (100 cm); half the list stays at 1.4 in (3.5 cm) or under
Temperature
64–82°F
18–28°C, most of the list
Light
5 low light
13 medium light · 6 high light
CO₂
21 no CO₂ needed
2 CO₂ beneficial · 1 CO₂ required
Growth
2 medium growth
22 fast growing
Difficulty
21 easy
3 medium

24 plants

The classic floaters

Amazon frogbit, dwarf water lettuce and the salvinias are the floaters most tanks end up with: rated beginner or easy, medium light, no CO₂, and roots that trail down for fry and shrimp to hide in. Red root floater turns red under strong light and stays green under weak. All of them grow fastest when the surface is still, so keep the filter outflow away from them or fence off a corner with a ring of airline tubing.

Duckweed and its relatives

Duckweed, spirodela and watermeal are the smallest plants in the catalog and the hardest to get rid of. A single leaf in a plant bag colonizes the surface in weeks, and every net and hand that leaves the tank carries some. That makes them a superb nutrient sponge for a fry or shrimp tank and a nuisance everywhere else. Decide which you are keeping before it decides for you.

Stem plants that float

Hornwort, guppy grass and Najas indica have no real roots and are just as happy drifting as planted. Left loose they form a thicket at the surface that livebearer fry disappear into, and they grow in low light with no CO₂. Floating water sprite is a fern that does the same job with broader leaves.

Floaters for ponds and open-topped tanks

Water poppy, the mosaic plant and water hyacinth want strong light and room to spread, and they belong in a pond or an open tank under a bright light rather than under a hood. Water hyacinth is invasive across much of the world, so it never goes into a natural waterway or down a drain, and it is banned in some places. Check before you buy.

By the numbers

Smallest

  1. 01
    Watermeal (Wolffia globosa)

    Watermeal

    Wolffia globosa

    0 in (0.1 cm)
  2. 02
    Duckweed (Lemna minor)

    Duckweed

    Lemna minor

    0.4 in (1 cm)
  3. 03
    Giant duckweed (Spirodela polyrhiza)

    Giant duckweed

    Spirodela polyrhiza

    0.4 in (1 cm)
  4. 04
    Star duckweed (Lemna trisulca)

    Star duckweed

    Lemna trisulca

    0.4 in (1 cm)

Tallest

  1. 01
    Hornwort (Ceratophyllum demersum)

    Hornwort

    Ceratophyllum demersum

    39.4 in (100 cm)
  2. 02
    Guppy grass (Najas guadalupensis)

    Guppy grass

    Najas guadalupensis

    35.4 in (90 cm)
  3. 03

    Najas indica

    23.6 in (60 cm)
  4. 04
    Floating water sprite (Ceratopteris cornuta)

    Floating water sprite

    Ceratopteris cornuta

    15.7 in (40 cm)

FAQ

Common questions

Do floating plants need CO₂?

Almost none of them. Their leaves take carbon dioxide from the air, which is why they grow faster than anything rooted. Only riccia lists a CO₂ need on this page.

Which floating plants are good for a betta tank?

Frogbit, salvinia and water sprite. They give the fish shade and a resting spot near the surface and leave open water to breathe at. Thin them so at least a third of the surface stays clear.

Why are my floating plants dying?

Usually wet leaves. Splashing from a filter, condensation dripping from a lid or a current that flips them rots the leaves. Calm water, a gap between the surface and the lid and a weekly dose of fertilizer fix most of it.

Do floating plants block too much light?

They will if you let them. Plants below a solid mat of frogbit go dark within days, so thin the floaters weekly or keep them to one part of the surface with a floating ring.

Is duckweed good or bad for an aquarium?

Both. It strips nitrate and shades algae out, and it never leaves once it arrives. Good in a fry tank or a shrimp tank, a nuisance in a display you want to see into.

Can floating plants live in a pond?

Water lettuce, frogbit, salvinia and water hyacinth are pond plants first. Never release them into a natural waterway, and check local rules, since water hyacinth in particular is banned in some places.

Index

All floating plants

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