Where the ocean meets outward flowing rivers, saltwater and freshwater mix. These areas are called estuaries, mangrove swamps, and salt marshes. The water, which is part saline and part fresh, is referred to as brackish. These brackish waters are home to an amazingly diverse and unique group of animals, some of which are commonly available to keep in the home aquarium. These fish include archers, scats, monos, certain livebearers, gobies, and others. This article will explain how to create and maintain the proper home environment for many of the commercially sold brackish water fish.
Why should you chose a brackish aquarium? Brackish water aquariums, as mentioned above, are unique. They are usually conversation pieces and allow your aquarium to be different than most others. They also, despite some myths, are easy to maintain since the fish from brackish waters are designed to withstand frequent salinity and water parameter changes unlike both fresh and saltwater fish.

        The equipment you will need for a brackish water tank is similar to a freshwater tank but with a few additions. You will need:

• Aquarium. Some articles claim that a 55 gallon or larger aquarium is required for brackish water aquaria but this is untrue. You could go as low as a 10g or even a 5.5g. The recommended set-ups later in the article may help you chose tank size.

• Filter. The best filters for a brackish tank are hang on the back mechanical and bio-wheel filters or canister filters. Undergravel filters will not work properly with a sand substrate. For aquariums larger than 20 gallons, you should use 2 filters on opposite sides of the tank. You will want to have your water turned around 10 times per hour (so you would need a single 300gph filter or two 150gph filters for a 30g tank).

• Heater. Never go cheap on a heater. Submersible heaters are much better at spreading heat and are less likely to shatter. Make sure you get a heater marked for fresh AND saltwater use. You also need to make sure the heater is adequate in size. A rule of thumb is 5 watts of heat per gallon.

• Glass Top/Light Hood. All tanks should be covered and brackish tanks are no exception. Keep in mind, also, that brackish water evaporates faster than fresh water. If you plan on keeping plants, get atleast 1.5 Watts of light per gallon of water.

• Thermometer and Hydrometer. You will need the thermometer to keep the temperature and a hydrometer to measure the salinity of the water. A cheap swing handle hydrometer is fine for this situation.

• Substrate. Brackish water areas always are covered in a sandy, silty, or muddy material and I feel that sand is the best option for a brackish water aquarium. You could use marine aragonite, "Minerial Mud", or play sand (which can be found VERY cheap at hardware and home improvement stores). If you plan on keeping live rooted plants, you will need about a 1" layer of substrate (avoid larger layers as they can build up anaerobic spots) and for a fish only tank, a very thin layer is best.

• Marine Salt. I prefer Instant Ocean but most brands should work. AVOID Freshwater Aquarium Salt as this is not the proper salt to use in brackish or marine tanks (although it is fine in full freshwater tanks to fight off parasites).

• Water Condtioner. As with all aquariums, you will need a product to remove chlorine and chloramine from your tap water before placing it in the tank. Make sure the product is listed for both fresh and saltwater use.

        Brackish water fish do not all come from the same brackish waters. Some are found in the slow flowing estuaries and mangrove swamps while others are found in the fast flowing saltier ends of rivers. Fish, as you would expect, do better in as close to natural condtions as possible and therefore I have split the brackish category into 3 setups.

Set-Up #1: Estuary

        Estuaries are most people's idea of where brackish water occurs. Estuaries are slow-moderate flowing and the aeration from your filter(s) should be adequete. Although there will be set-ups for smaller tanks down the line, an estuary tank is best with a quite large aquarium.

Plants:
Plants in this tank are very likely to be eaten. Java Fern and Java Moss MAY survive. After raising your specific gravity over 1.015, these plants will begin to die off and they should be replaced with marine algae such as Caulerpa.

Temperature:
80-82 F

pH Level:
7.5-8.5

Decoration:
Sparesly decorate with rocks and branchy driftwood (that has been cured to prevent leaks).

Salt:
All of the fish listed above migrate down the estuary to the ocean when they are several years old, so you will have to mimic this the best of your ability. Buy all of your inhabitants young and start this tank with around 2 tablespoons of marine salt per gallon of water. Every 6 months, add an additional tablespoon of salt per gallon of water during water changes. Stop when you are adding about 7 tablespoons of salt per gallon of water or when your hydrometer measures a reading of 1.020-1.025. This should take about 3-4 years and they should not be rushed into full marine water. Keep in mind NOT to add the salt directly to the tank.

Set-Up #2: Brackish River

        Towards the end of the outward flowing rivers that empty into estuaries, there is brackish water. These are fast flowing regions and you should attain an additional powerhead directed to flow to the side to provide increased aeration and movement. These set-ups are a great home to mollies, gobies, puffers, and silversides and (in the case of Bumble Bee gobies) can be as little as 5.5 gallons.

Inhabitants:

Plants:
Anubius, Vallisneria, Hairgrass, and Java Fern are best suited to the currents of this tank although plastic is probably the best choice.

Temperature:
80-84 F

pH Level:
7.5-8.5

Decoration:
Decorate with taller plants in the background and shorter ones on the side. Add one or more rock cave for your gobies. Anubius and Java Fern should be attached to the rock cave(s).

Salt:
Around 1-2 tablespoons of marine salt per gallon of water or a specific gravity of 1.005-1.010 will be adequate for the full lives of most of these fish. Green Spotted Puffers prefer saltier conditions with around 3-5 tablespoons of marine salt per gallon of water or a specific gravity of 1.010-1.020.

Set-Up #3: Mangrove Swamp

        Mangrove swamps are slow flowing waters covered in floating plants and mangrove roots. These set-ups are designed to be part land, part water. For this reason, it is recommended to use a 55g or larger aquarium so that there is enough swimming room for the fish. The best filtration method in this case would be a cannister filter with enough tubing to extend into the water.

Inhabitants:

Plants:
Mangroves are the obvious choice for this tank. They should be planted on the edge of the water and on the land section. As for aquatic plants, since most are not readily available, plastic plants are best but you could try Java Moss, Java Fern, Cryptocorne Bekketti, Hairgrass, and Vallisneria.

Temperature:
82-86 F

pH Level:
7.5-8.5

Decoration:
The usage of tree root ornaments would be ideal in this setup. Many mangroves and partially subdued lighting will make this tank more realistic. These swamps usually also have floating plants covering the surface but most of these plants are not available commercially (although you could try java moss).

Salt:
Around 3 tablespoons of marine salt per gallon of water or a specific gravity of 1.010-1.015 will be adequate for the full lives of these fish

         Once you have set-up your tank to your desired brackish set-up and have fully cycled the tank, you will have to learn a schedule of maintenance to care for your tank.

        I am a firm believer of frequent water changes. I recommend cleaning 15% of your water once a week. When adding the replacement water, make sure you add about the same dosage of salt as before (unless you are running the estuary set-up, in which case the dosage increases every 6 months). It is not necessary to check with a hydrometer since these fish are naturally familiar to varying levels of salinity but you should be within a good range of accuracy to prevent shock.

        One to two times a week, you should stir up the sand with the back end of a fish net. After stirring, turn the fish net to scoop the debris you have stirred up into the net. If you are using 1" of sand or more, this stirring also helps prevent anaerobic spots from forming (these spots can release deadly gases into your tank).

        Feeding should be done atleast 2 times daily. All of the forementioned brackish set-ups are recommended to have warm water (atleast 80F) and this increases the fish's metabolism, causing them to eat more food and grow faster. So, 2-3 feedings a day is much preferred, with 3 being optimal. Many of these fish (mollies, monos, scats, knight gobies) require some vegetable matter in their diet and puffers should be fed snails on occassion to reduce the size of their "beak".

  Once you have set up your brackish water aquarium and have become accustomed to the required work, you will have created an entertaining and low maintenance aquarium with some of nature's most unique and wonderous creatures.

Email the Author

Illustrations used in top banner courtesy of Popular Freshwater Tropical Fish

The set ups and recommendations in this article are the opinions of the author. Badman's always wants to provide the best information available, so if you have a comment or an additional recommendation please Email me and I will add them here. Your comments: From: Debbs Date:1/12/05 Here there is a recommendation of GSP's in a brackish set up. But what people don't know, is that GSP's do not stay brackish. At 4-5" they need to acclimate to full marine to live a full, healthy life. So you have the GSP's mixed with Bumblebee Gobies. The gobies need to stay brackish, therefor there is a confliction of water requirements with these two species in the long run. Also, the max GSP's (full grown) in a 55 gallon should be 2, and that's pushing it. Each GSP requires at least 30 gallons for himself. The reason is not only the bio-load but the aggression of the fish in small quarters.

Main index Navigation Badmans Tropical Fish! Fishkeeping ABCs Favorite Fish Fish Families Detailed Information In Depth Definitions Natures Way The Equipment Whats That Mean? Want More Just For Fun Guestbook Site Search, What's New