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Black Water Aquarium Tips

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Some fish hobbyists change the chemistry of aquarium water to fit the native environment of their fish. Setting up a black water aquarium will match South American and Asian streams filled with dead wood, leaves, and peat.

Blackwater streams are slow moving and have a low pH because of the dead leaves and wood that has accumulated in the water. This is the normal environment for popular South American fish such as Angelfish, Tetras, Dwarf Cichlids, Corydoras, Plecostomus, Discus and others. A blackwater tank enhances the color and health of fish native to that environment.

BlackwaterBlack water aquarium Additive

Water in blackwater streams is brown. Aquarists can reproduce this water for their tank with a commercially made extract specifically made for aquarium use.

TIP: Being able to keep blackwater chemistry consistent is an advantage of using a black water extract as it is formulated to strict manufacturing standards.

An aquarist can make their own by boiling leaves, such as oak, in water and using this for water changes and setting up the tank. Making the extract this way allows the aquarist complete control over the end result, but they should be well informed on the chemistry.

Sphagnum Peat Moss

Using sphagnum peat moss is another way to make blackwater. Replacing carbon in the filter with the peat moss lowers the pH and makes the water more acid. Carbon filters need to be removed as they eliminate the effects of the moss. Put in a mesh bag and soak to remove some of the tannins before use. Replace the moss periodically as the tannins deplete.

Bogwoodmopani wood fish tank, Driftwood and Mopani Wood

Woods such as bogwood, driftwood and Mopani wood provide decoration as well as making blackwater. These woods should be soaked long enough for them to absorb enough water to sink before using them in an aquarium. The soaking also removes possible harmful minerals. While well rinsed woods will provide some tannin to the tank, it shouldn’t be the primary source of tannin for the tank.

TIP: Change the water frequently the first few soakings to remove excessive tannin.

Bogwood is wood preserved in peat bogs for years where peat tannin has soaked into the wood and preserved it. Soak in hot water to remove some of the tannins before placing the wood in an aquarium. Doing that controls how brown the aquarium water will turn.

Driftwood can be good for a blackwater aquarium. The hazard of driftwood is that it has absorbed minerals and salt water. To use driftwood, soak in water to remove them. Driftwood from the ocean is much more susceptible to retaining harmful minerals.

TIP: Driftwood from freshwater streams is preferred as it contains less minerals that what is found in ocean driftwood.

Mopani Wood is from the African Mopane tree. This is a gnarled hard wood that makes for an interesting aquarium décor. Follow the same procedure as with other woods.


Blackwater fish are in a slow moving environment in their native habitat. That would mean a controllable filter that doesn’t have a continuously high flow rate. For a blackwater tank, a filter with an adjustable flow control is the best.


Do water changes more frequently with a blackwater tank to keep the chemistry in control.

Test the water frequently to make sure the pH is in control, and it can change quickly. Selecting the correct amount of peat is a guess, and will affect the chemistry. Less is better than more.


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