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.
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.
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.
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.
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.