Setting up a Brackish Water Fish Tank
Starting an Aquarium That is Neither Saltwater or Freshwater
Dec 23, 2008
A brackish water tank is a unique setup in the aquarium world. In the wild, brackish water occurs when freshwater rivers flow into the ocean. Brackish habitats include estuaries and mangrove swamps and there are also some brackish seas and lakes. In areas where rivers flow into the ocean, salinity (or the amount of salt in the water) will vary depending on the tides. The fish and other creatures that live in the regions are adapted to handle salinity levels that change with the tide and currents.
Basics of a Brackish Tank
When it comes to setting up a brackish tank, you can treat it like a freshwater tank. Although you can use a power filter, a canister filter is better because splashing from the power filter can cause salt creep, a build up of salt when splashing water lands on something other than the inside of the tank.
A heater is a must to maintain the appropriate temperature in the tank. The substrate can be anything, though sand is a popular choice for these tanks. There are some plants that will survive in light brackish water, but most times you are better off with plastic or silk plants.
Salt Levels in a Brackish Water Tank
You will need either a hydrometer or a refractometer when setting up a brackish water tank. These instruments are used to measure the amount of salt in the water. Typically, a refractometer is recommended over the hydrometer in a saltwater setting to ensure that the tank is very close to the ocean’s salt content. For a brackish tank, a hydrometer will do because the salt level does not need to be precise and can fluctuate a little from water change to water change.
A brackish water tank is usually kept at a specific gravity from 1.005 to 1.015. Past that the water really becomes closer to saltwater and would benefit from just being raised to full saltwater at 1.025. For reference, 1 cup of salt per 5 gallons of water results approximately in a specific gravity of 1.005.
Brackish Water Fish
There are quite a few fish that thrive in a brackish environment. Some smaller fish include Figure Eight Puffers and Knight Gobies. Both stay under four inches and do well in salt around 1.005 SG. For the most part these two will get along and can be kept in a tank together, however, realize that puffers are individuals and while one may tolerate tank mates, another one may not.
Some other puffer options include the Green Spotted Puffer Tetraodon nigrovidis and the Ceylon Puffer Tetraodon fluviatilis. Both grow up to six inches with the Ceylon puffer typically topping out closer to 8 inches. These puffers do very well in saltwater as adults.
Some unique fish for the brackish tank include Archerfish and Anableps. Archer fish are skilled insect hunters and capture insects by either jumping out of the water or shooting a stream of water at the insect to knock it into the water. Both Archers and Anableps can grow to around 12 inches in length. They are unique because their eyes are divided so that they can look above and below the water at the same time.
There are quite a few options for fish in the brackish tanks. This type of tank can provide a welcome change from the usual collection of freshwater fish, and is a nice stepping stone to saltwater.
Information provided by Damien Wagaman, December 23, 2008.
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