Marine Plants

Although most of the attention in saltwater aquariums are given to live rock, corals, and the colorful fish, there are many marine plants available that can make a great addition to many saltwater aquariums. These would not typically include aquariums with fish that like to graze on algae but for many fish only systems including small reef systems and seahorse tanks they are a great addition and will help improve the water quality and reduce overall maintenance.  Also, they can really be aquascaped just like any freshwater planted aquarium.  You are only limited by your imagination and motivation!

In the aquarium trade the term “marine plants” can be used to describe both macro algae and sea grass. Unlike sea grass, macro algae are not true plants but are actually large celled algae and absorb nutrients through their cell structure. Marine plants and macro algae are photosynthetic and rely on the sun’s energy for food and serve as the base of our ocean’s food chain.

Marine plants basically require the same essential nutrients as other aquatic and terrestrial plants do. Even though most grow in sandy soil, they will benefit from a little aquarium soil in the location where they are planted to ensure they have enough micronutrients.

Marine plants can be found throughout the world at varying depths and environments. This means that some are more suitable for an aquarium than others. Some species are fast growing, invasive and can be a nuisance in any aquarium, especially reef tanks. Some species of Caulerpa have been outlawed due to being an invasive species. Still, many are safe and appropriate for the aquarium.

There are three main classifications of marine macro algae. They are Chlorophyta (green algae), Phaeophyta (brown algae), and Rhodophyta (red algae). All of these classes also contain slightly calcified or heavily calcified algae, which depend upon properly maintained calcium levels to grow and reproduce. Sea grasses have their own classification (Magnoliophytae or Angiospermae). There are also the mangrove plants that are often used by hobbyists in the marine aquarium although they do require an area where they will grow out above the water. This will limit mangroves to a refugium unless you have a specialized aquarium set up.

This web page will mostly focus on just a few species of commonly available marine plants.  There are many others available from specialized sources and internet sites.   There are not a lot of brown macroalgae available presumably because it’s not as attractive as the red and green varieties.  There are many species of red and green macroalgae commonly available however.  There a few places that will carry seagrass but it is not nearly as common as macroalgae.  Mangroves are common but do require a highly specialized set up.


Mangroves and their ecosystems grow in the intertidal waters of the tropical oceans of the world. Their seeds and small “propagule” or saplings are commonly available for sale.

MANGROVE PICTURE  – Mangroves can be planted in the sand, or in between rocks in a specialized open topped aquarium or an illuminated sump or refugium. Some aquarium soil substrate will also be appreciated by the mangroves.  The roots will quickly form and take hold in sand substrate or in live rock.  Lighting appropriate for a planted tank will be necessary.

Mangroves absorb nutrients from the water in order to grow, and improve overall water quality like other aquarium plants will.  When leaves are dropped from the plant they should not be allowed to decay in the aquarium.

They can grow in fresh, brackish and saltwater. They are even suitable for ponds in tropical areas where they will not be exposed to near freezing temperatures. Be sure when planting that the leaves are out of the water.

One should wipe the excess salt from the leaves with fresh water a few times per week and trimming the growth tip of the plant to control growth.

Shaving Brush Plant

These are macroalgae available for the saltwater aquarium. These attractive plants will help reduce nitrate and phosphate from the water column.

Brush Plants grow in sandy shallow water fields throughout the world. They have a long, tubular stalk with a multitude of long, thin “leaves” growing in a feathered fashion, usually at the tip of the stalk. They will need lighting appropriate for a planted aquarium. Shaving Brush Plants are also a good fit for refugiums and illuminated sumps.

Most herbivorous fish and invertebrates will not normally consume this plant, but some sea urchins may uproot and consume this species.


The Halimeda plant is a macroalgae found within tropical oceans worldwide, and is a common decorative plant for a marine aquarium. Also called the “Money Plant,” the irregular oval segments of Halimeda appear as several small green coins glued from end-to-end, forming a chain.  Calcareous algae deposit calcium carbonate in their tissues, and require a sufficient calcium level in the aquarium.

Halimeda are a hardy and stable addition to a marine aquarium and few fish will feed on it. It is not an invasive and won’t cause harm to close neighboring corals or invertebrates.  They will need appropriate lighting and calcium as well.  However, they are not as tolerant of poor water quality compared to some other algae and do not tolerate extensive pruning.

Maidenhair’s plant

Chlorodesmis is a green filamentous algae that looks like tufts of hair and is sometimes found hitchhiking on a piece of live rock.  Common names include Maiden’s Hair Plant or Turtle Grass. A chemical in the plant deters herbivorous fish from eating it.

Provide the Maiden’s Hair plant with a moderate to strong water current and lighting. These plants are great breeding ground for beneficial crustaceans like amphipods and copepods. This species is known to be sensitive to high nitrates and all copper.

Mermaid’s fan plant

The Mermaid’s Fan plant, like Halimeda, is a green calcareous algae found in the Caribbean and often available for use as a decorative plant in the marine aquarium. These plants have short stems that grow out of the substrate or live rock and then form a fan like leaf that is oval to round in shape. They are calcareous algae that deposit limestone (calcium carbonate) in their tissues.

The Mermaid’s Fan plant is generally hardy but they require sufficient lighting and calcium and most herbivores will avoid them.

Red Macroalgae species

Red Macroalgae belong to the genus Rhodophyta and is the largest and most diverse group of tropical and temperate marine algae. Their dominant pigment is phycoerythrin, which gives off rich shades of red, orange and blue. Red macro algae can be some of the most varied and striking of all marine algae and are sometimes found in many forms for saltwater aquarists.  In fact, the coralline algae that covers live rock and makes it purple in in fact a Rhodophyta species.  There are even branching forms of reef building Coralline algae.  They actually utilize carbonate as an energy source.  That is why carbonate additives are needed for coralline algae to thrive.  However, as with corals, there are also many that do not actually build carbonate skeletons.  Red Macroalgae will need lighting suitable for other planted or coral reef tanks.

Sea Grass species

Sea grasses are also sometimes found available for the saltwater aquarium.  Sea grasses are a productive group of marine plants found in the ocean, forming extensive meadows in shallow, nutrient-rich environments that occur in tropical and sub-tropical waters worldwide. Sea grasses provide shelter and habitat for juvenile fish and invertebrates, and effectively filter near-shore habitats of nutrients, creating an oxygen rich environment. They are also an important component of the coral reef by filtering and buffering the flow of water and trapping sediments before they reach delicate corals.  They will require deep sand beds as their root systems are extensive and demand for organic nutrients high so a base of aquarium soil would be beneficial.