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Tag Archives: Plants for Brackish Aquariums

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Algae and Plants for Brackish Water Aquariums – Part II: Adapting Freshwater Plants to Brackish Aquariums

Hello, Frank Indiviglio here.

Please see Part I of this article for information concerning typical brackish water plants and algae.

A number of well-known freshwater aquarium plants adjust quite nicely to brackish water.  Given the great variety of species that are available, I’m sure many others will be found.

Experimenting With Freshwater Plants

If you are of a mind to experiment, first research various natural habitats, keeping an eye out for plants that thrive along coastlines, estuaries and in other such situations….these might be exposed to salt water during floods or at high tide.  In general, freshwater plants with waxy leaf and stem coverings make the best prospects with which to begin.

Bear in mind that the change from fresh to brackish water is an extreme one, and can easily shock your plants.  Treat them as you would a new, delicate fish and increase their exposure to brackish water gradually.  For untested species, you might consider dripping brackish water into the plant’s tank via a section of airline tubing during the acclimatization period.

Anachris (Egeria) densa

Much favored by freshwater aquarists and a standby for grammar school science experiments, Anachris is very hardy and highly recommended for use in brackish tanks.  Most agree that it is the most likely of all freshwater plants to thrive in this foreign environment.

Anachris grows well as a rooted or floating plant and, in strong light, can add an inch or more a day to its length.  Cuttings taken anywhere along the stem will grow into new plants.

Temple Plant, Hygrophila corymbosa

This most attractive of aquarium plants does very well in brackish water, but is considered a delicacy by snails, hermit crabs and many fishes.  It and related species, which are native to South and Southeast Asia, can be propagated from cuttings and grow best under bright lights.

Cabomba aquatica

Another popular freshwater plant, this South American native has delicate leaves which cannot withstand the attentions of herbivorous fishes and invertebrates.  However, when housed with halfbeaks, mudskippers and others that will not molest it, Cabomba makes a fine addition to the brackish aquarium.

Aquatic Grasses – Sagittaria and Vallisneria

Sagittaria, relatively impervious to salt water damage and unpalatable to most organisms, is one of the best freshwater plants to use in brackish systems.  The widely-available grass Vallisneria does very well also, even under subdued lighting, but is considered a tasty food by many aquatic animals.

Hornwort, Ceratophyllum demersum

Reaching 10 feet or more in length in the wild and equally at home in cold and warm water, this hardy survivor is an excellent candidate for brackish water tanks.  It can get by in dimly-lit aquariums, but in such situations its foliage will pale considerably.

Water Sprite, Ceratopteris thalicroide

Even in such an unnatural environment as brackish water, this plant will grow quite vigorously if kept warm and under bright lights.  It can be maintained either floating or rooted, and in different situations will develop rounded, bulky or fern-like leaves.  Water sprite’s prodigious rate of growth often compensates for the attentions of plant-eaters.

Chain Swordplant, Echinodorus tenellus

This attractive plant spreads rapidly via runners (hence the “chain” portion of its name) and is fully grown at 4 inches in height.  As is true for its larger relatives, the chain sword requires warm water and a well-lit environment.

Further Reading

Anachris (Egeria) densa is widely introduced in the USA and elsewhere.  The University of California has posted an interesting account of its natural and unnatural history at http://ucce.ucdavis.edu/datastore/detailreport.cfm?surveynumber=182&usernumber=43.


Please write in with your questions or to relate your own experiments with aquatic plants.  Thanks, until next time, Frank Indiviglio.

Algae and Plants for Brackish Water Aquariums

Hello, Frank Indiviglio here.

The culture of live algae and plants in brackish aquariums has not been given much attention, and few plants native to estuaries and similar environments are commercially available.  However, as with fresh water tanks, live plants add a whole new dimension to aquarium-keeping, and are extremely interesting in their own right.

In brackish exhibits at the Bronx Zoo and in my own tanks, I have experimented with several varieties of algae and plants.  In addition to mangroves, Java ferns and other such estuarine-adapted species, a surprising number of plants and algae that are typically thought of as either “marine” or “fresh water” can be acclimated to brackish environments.  Following are a few of my favorites.


Plants and algae should be introduced carefully to a brackish water aquarium…treat them as you would a fish or invertebrate.  Particularly as concerns fresh-water plants, sudden changes in pH can wreck havoc with osmotic pressure, causing cell rupture and the death of the specimen.

Marine Algae

Marine algae are commonly referred to as “seaweeds”, but they are in actuality not true plants.  Single or multi-celled, algae lack roots, stems and leaves, but have evolved equivalent structures. For example, holdfasts act as roots in anchoring them to the substrate, but do not absorb nutrients…that role is taken on by the leaf-like portions of the organism.

Caulerpa prolifera

This is the most commonly-available marine algae.  It ranges from Florida and the Caribbean southward, and is commercially cultivated.  Caulerpa spreads via rhizomes, or runners, and, although a true marine algae, it adjusts well to brackish environments.

Like all algae, Caulerpa may leak fluids when pruned, so be sure to clip only a tiny amount at a time if trimming is necessary.  Related species, with rounded, pointed or fern-like shapes, are sometimes seen in the trade.

Other Types of Marine Algae

A number of other types of marine algae are sometimes available.  While not as well-suited to a brackish water existence as Caulerpa, several will adjust if care is taken in the acclimatization process.

I and colleagues have had varying degrees of success with sea cactus (Udotea flabellum), Codiacea spp., mermaid’s cup (Acetabularia spp.), mermaid’s shaving brush (Penicillus capitatus) and several types of red algae.

Brackish Water Plants

Java Fern, Microsorium pteropus

To my knowledge, the Java fern is the only true brackish water aquatic plant that is regularly available to aquarists.  In well-lit tanks it will proliferate rapidly.  A number of fishes favor Java fern leaves as food, but its rapid growth rate can accommodate this in many cases.

Red Mangrove Seedlings, Rhizophora mangle

Mangrove seedlings, or propagules, are semi-aquatic, with the roots usually submerged and the plant itself growing above water.  The red mangrove is often sold in the trade and is commercially propagated in Florida, where it also occurs naturally.  Red mangroves are extremely wide-ranging, being found along coastlines in many of the world’s tropical and subtropical regions.  At home in estuaries, salt marshes and along river mouths, they are adapted to fluctuating salinity levels, and fare well in brackish water aquariums.

Mangroves can be planted in mud or wedged into limestone, and, because of their semi-terrestrial nature, are best kept in aquariums housing mudskippers, fiddler crabs and other creatures that utilize both land and water areas.  They excrete salt on the surface of their leaves…this should be washed away with fresh water every few days.

Mangroves often grow slowly in the aquarium, and stay at a manageable size for some time.  There are a few techniques for dealing with tall plants…please write in if you would like further information.

Eelgrass, Zostera marina

Eelgrass is one of the only true plants to live an aquatic existence in marine environments.  It is not commonly kept in aquariums.  I have had mixed success with it, but have observed healthy stands in commercial aquariums (if you are interested in this plant, please write in and I’ll make some inquiries to public aquarium contacts).

Eelgrass populations have plummeted in the northeastern USA and elsewhere, and I encourage those with an interest to work with this plant (please note that collection is prohibited in California and elsewhere).  An incredible assortment of unique fishes and invertebrates, such as pipefishes, dwarf seahorses and eelgrass-shaped amphipods, are always found in association with eelgrass beds.

I commonly observe eelgrass in estuaries, lagoons and other brackish habitats, and it thrives in true marine water as well.

Next time I’ll discuss some of the many fresh water plants that can be acclimated to brackish conditions.  Please write in with your questions and comments.  Thanks, until next time, Frank Indiviglio.

Brackish environments are home to many fascinating fishes and invertebrates that do well in aquariums.  Please see my article on Mudskippers  for a look at one of the most unusual.