A brackish-water aquarium is an

aquarium An aquarium (plural: ''aquariums'' or ''aquaria'') is a vivarium of any size having at least one transparent side in which aquatic plants or animals are kept and displayed. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, aq ...

where the water is

brackish Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuari ...

(semi-salty). The range of "saltiness" varies greatly, from near freshwater to near marine and is often referred to as specific gravity (SG) or salinity. Brackish water aquaria is a popular specialization within the

fishkeeping Fishkeeping is a popular hobby, practiced by aquarists, concerned with keeping fish in a home aquarium or garden pond. There is also a piscicultural fishkeeping industry, serving as a branch of agriculture. Origins of fishkeeping Fish have ...

hobby. Many species of fish traded as

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include ...

species are actually true brackish species, for example mollies, Florida flagfish, and some

cichlid Cichlids are fish from the family Cichlidae in the order Cichliformes. Cichlids were traditionally classed in a suborder, the Labroidei, along with the wrasses ( Labridae), in the order Perciformes, but molecular studies have contradicted this ...

s such as chromides and black-chin tilapia. There are also several popular species traded purely as brackish water fish, including

monos Monos is an island in the Republic of Trinidad and Tobago. It is one of the "Bocas Islands", which lie in the '' Bocas del Dragón'' (''Dragons' Mouth'') between Trinidad and Venezuela. It is so named as the island was once home to noisy red h ...

spp,

scats The Sydney Coordinated Adaptive Traffic System, abbreviated SCATS, is an intelligent transportation system that manages the dynamic (on-line, real-time) timing of signal phases at traffic signals, meaning that it tries to find the best phasing (i ...

archerfish The archerfish (spinner fish or archer fish) form a monotypic family, Toxotidae, of fish known for their habit of preying on land-based insects and other small animals by shooting them down with water droplets from their specialized mouths. ...

, and various species of pufferfish,

goby Goby is a common name for many species of small to medium sized ray-finned fish, normally with large heads and tapered bodies, which are found in marine, brackish and freshwater environments. Traditionally most of the species called gobies have b ...

flatfish A flatfish is a member of the Ray-finned fish, ray-finned demersal fish order (biology), order Pleuronectiformes, also called the Heterosomata, sometimes classified as a suborder of Perciformes. In many species, both eyes lie on one side of the ...

, and

gar Gars are members of the family Lepisosteidae, which are the only surviving members of the Ginglymodi, an ancient holosteian group of ray-finned fish, which first appeared during the Triassic, over 240 million years ago. Gars comprise seven livin ...

. Generally, aquarists need to maintain a

specific gravity Relative density, or specific gravity, is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for liquids is nearly always measured with respect to water (molecule), wa ...

of around 1.005 to 1.010 depending on the species being kept, but practically all brackish water fish tolerate variations in

salinity Salinity () is the saltiness or amount of salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal ...

well, and some aquarists maintain that regularly fluctuating the salinity in the aquarium actually keeps the fish healthy and free of parasites.

Aquarium maintenance

Brackish water species can be kept mainly the same as standard freshwater aquaria, but a hydrometer is used to check the salinity of the water. Certain kinds of brackish water fish need to have their salinity increased slightly every six months. The tank sizes can vary widely depending on the needs of the particular species, and the temperature is usually in the tropical range of 76-82 °F. The substrate can vary from sand to gravel, but many aquarists choose crushed coral or

aragonite Aragonite is a carbonate mineral, one of the three most common naturally occurring crystal forms of calcium carbonate, (the other forms being the minerals calcite and vaterite). It is formed by biological and physical processes, including prec ...

sand, both of which help raise the hardness and pH to an acceptable level. Many brackish water fish, as any fish, can jump out of the tank, so it must be covered. Some brackish water species come from estuaries. These should have a slow moving current and some hiding places in their aquarium. Some come from larger rivers. These should have plants around the perimeter of the aquarium with some large rocks to rest on. Others come from mangrove swamps. These should have a few mangrove plants, and some species should have a beach to climb out on. Some freshwater species (and the blacktip shark, a marine species) are hardy enough or survive better in brackish water, such as ''

Polypterus bichir ''Polypterus bichir'', the Nile bichir, is a fish which lives in the Nile and some of its tributaries in Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 millio ...

'', certain

loach Loaches are fish of the superfamily Cobitoidea. They are freshwater, benthic (bottom-dwelling) fish found in rivers and creeks throughout Eurasia and northern Africa. Loaches are among the most diverse groups of fish; the 1249 known species of ...

es, ''

Danio rerio The zebrafish (''Danio rerio'') is a freshwater fish belonging to the minnow family (Cyprinidae) of the order Cypriniformes. Native to South Asia, it is a popular aquarium fish, frequently sold under the trade name zebra danio (and thus often ...

'', all kinds of mollies but especially the Yucatán molly, and some

gobies Gobiidae or gobies is a family of bony fish in the order Gobiiformes, one of the largest fish families comprising more than 2,000 species in more than 200 genera. Most of gobiid fish are relatively small, typically less than in length, and the ...

. All can tolerate the same amount of salt in aquaria, but should be acclimated slowly.

External links

Aquariacentral Brackish Water Forum FAQ

Aquarium maintenance

See also

External links

Further reading