Freshwater Frogbit Plants for an Aquarium

• Frogbit plants are floating freshwater plants that make a great addition to a planted aquarium. Floating plants help small fish and fry hide from larger fish as well as provide places for micro-organisms to grow. Many fish feel more comfortable with the protection of the plants above them. Frogbit is easy to grow and grows quickly provided there is enough light available.

Amazon Frogbit

• Amazon frogbit (Limnobium laevigatum) has round- to oval-shaped leaves about the size of a quarter. The tops are glossy green and the undersides are pale yellow-green. The thick leaves are full of air to help keep the small rosettes floating. The roots are very fine and can grow several feet and root in the substrate.

  Amazon frogbit likes very bright light in the aquarium with at least two 40-watt fluorescent tubes. The more light available, the faster it will grow, but hot lights such as metal halides can burn it without ventilation. The plants send out runners along the surface that produce baby plants. They eventually will form a dense mat and need to be thinned often so they do not shade the submerged plants. Amazon frogbit prefers temperatures in the low 70s to low 80s, which is the range for most tropical aquarium fish.

Spongeplant

• Spongeplant (Limnobium spongia), sometimes called American frogbit, is very similar to Amazon frogbit except it has heart-shaped leaves with dark speckles. New leaves have a reddish tint to them when there is a lot of light available. The rosettes are slightly less compact than Amazon frogbit when not grown in thick mats. Spongeplant gets its name from the spongy undersides of the leaves that help keep it floating.

  In the aquarium, spongeplant's use and care is the same as Amazon frogbit. The plant can be used to control algae by consuming excess nutrients and provide sections of shade for low-light-loving fish and plants living in a very bright aquarium.

European Frogbit

• European frogbit (Hydrocharis morsus-ranae) is most often seen in ponds or water gardens and is rarely grown in aquariums. It can withstand cold winter temperatures by forming buds that sink to the bottom of a pond then re-sprout in spring. European frogbit looks very similar to spongeplant but has slightly larger leaves that grow up to two inches. The undersides are thick and spongy and are colored purple. The roots grow to 12 inches long and do not root in the substrate.

  Like other floating plants, European frogbit likes plenty of light. It should be grown in full sun in a pond or water garden and in very high light in an indoor aquarium. It is very adaptable to water conditions and can tolerate temperatures much lower than tropical aquarium fish.