Blackwater Biotope

Blackwater Biotope

One of the most interesting aquarium setups that I've seen are blackwater aquariums.

Though not all aquarists are a fan of having a gloomy and cloudy-looking aquarium, there are things that you'll find interesting about blackwater biotopes. 

Let me walk you through the ins and outs of a blackwater biotope and explain why you should try this type of aquarium setup.

Blackwater Biotope Chap. 1: Things That You Should Know

What is a Blackwater Biotope or Blackwater Habitat?


When we say blackwater, what particular picture might come into your mind? 

You might think about the stagnant water left by last night's flooded rain or perhaps the murky and mysterious deeps of the Amazon river. 

Well, either of these two illustrates what black water looks like. 

A blackwater biotope as its name implies is a dark-colored body of water, just like what we mostly see on swamps, ponds, lakes, and rivers. 

So in simple terms, it is the "natural habitat of water-dwelling livestock". 

What Causes The Water to Turn Black?

The dark color of the water is a result of the tannin released by decomposing leaf litter and woody debris that falls into the water. 

As time passes, the tannin or the stain, then mix-up with the water resulting in a tinted-water or blackwater. Think of this process similar to what happens when you dip your tea bag into a cup of water and then letting it settle.

Acidic particles from the decomposed materials also contribute to the viscosity of the water, thus, making it not only dark but also thick-looking. 

Blackwater Biotope Chap. 2: Mimicking Nature

As we all know, the idea of a creating biotope is to mimic nature. So for aquarists who love challenging ideas, a blackwater-inspired biotope is for you. 

Here are the following elements and steps that you will be needing in order to set up your blackwater aquarium. 

Setting up Your Biotope Aquarium

blackwater aquarium setup

The perfect size aquarium  will help you emulate the characteristics of a blackwater habitat. 

I suggest using a medium to large aquarium that has cube-like dimensions, it may differ from a 10-500 gallon aquarium. But larger aquarium tanks will give you more room when you conceal and separate the heater and filter, which are hard to do if you use smaller ones. 

Putting a black or dark background not only helps you hide and conceal both heater and filter, but it also adds more sense of the deepwater idea you want to achieve. 

Keep in mind that activated carbon from your filter will remove the tannin from the water so it is best to remove it or use it seldomly. In this way, you can make sure that the dark color of the water will be preserved.

In case you want to add living plants to your aquarium, instead of only using sand, use fine gravels to hold the plants firmly. You can also have other dark-colored substrates for the bottom layers of your aquarium. 

For the bottom layer of your aquarium tank, the "dirted tank technique" can be utilized. An organic potting mixture will make it have more river bottom-liked appearance. 

Rocks that do not release alkaline and calcium can also be added as a decoration. 

For driftwood, any kind of aquarium wood can be used as long as it meets the water chemistry. You see, although blackwater may look thick, it is actually soft and acidic. This means the water is maintained at low levels of pH just like the levels of a natural body of water. 

A type of driftwood that is commonly used and known to release low levels of pH is Manzanita wood. This kind of wood has a pleasant appearance that blends well in a blackwater biotope. 

Obviously, the blackwater biotope is naturally dim so experiment with what lighting is perfect to capture the best appearance for the overall environment of the your biotope. 

Now, all we need is to add the blackwater to our biotope!

Adding the Blackwater to your Biotope

To achieve the dark brownish color of the water you will need to use a variety of leaves that can produce strong tannins. Though there are blackwater additives found available in the market.

But having organic substrate enrichment makes it more nature-like right? 

Native tree leaves that I can recommend include different types of oak tree leaves such as red oak, sessile oak, and turkey oak. These leaves' decay period is slow so you can replace them within a month or two. 

If you don't have access to oak leaves you can also try other types of tannin makers which most aquarists used including indian almond, dwarf magnolia, japanese maple,  and even alder cones. 

Preferably, boiling the dried leaves and cones for up to 1 hour will help you quickly reach the desired result. Boiled leaves released tannin faster than directly soaked leaves. They also sink quicker to the bottom of your aquarium. You can see the results within a day or two.

There are no strict limitations on how many leaves you'll need to use. Some may even prefer having a dense carpet of leaves to replicate what natural blackwater looks like. Dried palm frond can be submerged and added to make your aquascape more pleasant to look at. 

When it comes to your aquarium's water maintenance conducting pH and kH tests regularly for too high or too low levels can affect your livestock and botanicals. 

Twice a week is the best for checking and the ideal level should be around from 4.5 to 7. For accurate testing efficiently utilizing test kits such as ammonia and nitrite test kit, water hardness test kit, or low-range pH test kit can be a great help.

Before changing your aquarium tank's water, keep in mind to compare the condition of the new water that you will use to your current water condition. Also, make sure that you have de-chlorinated the water that you will use. Experienced aquarist chooses to let the water sit for a few days before using it as a replacement. In this way, too much differential of the water can be avoided. 

Now that your blackwater aquarium is all set, it's time to add the inhabitants. 

Blackwater Biotope Chap. 3: Plants and Animals that Suits Your Blackwater 

Same as the truth not all aquarists are a fan of having a murky aquarium, this is also true to plants and animals as not all are capable of adapting to this type of environment. 

Ornamental Plants For Blackwater Biotope

You will need to be picky when deciding what aquatic plants you want to have  especially if you'll incorporate floating plants and water motion in your aquarium. Because, there are only selected suitable plants that can survive in a blackwater biotope.

As you choose an aquatic plant make sure that it falls under the epiphyte category. What is an epiphytic plant? Here's a trivia. 

An epiphyte plant grows and lives by attaching itself to something such as decorations or even to other plants. This type of plant loves wet and well-shaded surroundings. This means it's perfect for a blackwater biotope. 

Here are some examples of these plants: 

  • Buce Plants
  • Crypts 
  • Java moss and Java fern
  • Amazon sword plant 
  • Indian water fern(also known as water sprite)
  • Flame moss
  • Anubias

One more thing, always remember not to bury the plant's rhizome under the substrate to avoid rotting. 

Fish Inhabitants for Blackwater Biotope

To complete your biotope we are now going to see what types of fishes can live in your aquarium. As we have already discussed blackwater is the natural habitat for a lot of fishes. So the fish that you will put in your aquarium depends on your setup. 

If you don't have any specific setup and only go for the blackwater rule, then any types of freshwater fish from natural blackwater will do. 

However, thoughtful research must be done because some of these fishes can get big, and your aquarium might become small for its future size. 

Here are some of the common fishes that can succeed inside your blackwater biotope:

  • Tetras
  • Catfish
  • Brycons
  • Gouramis
  • Cichlid 
  • Loaches
  • Angelfish
  • Bettas
  • Rasboras
  • Pufferfish
  • Danios
  • Knifefish
  • Geophagus

Be careful though, even if these fishes share the same type of habitat it still does not conclude that they can work well if put in the same aquarium. 

Some Final Thoughts 

Blackwater tanks provide comfort not only to us aquarists, but also to our dear fish. As we(both new and experienced aquarists) enjoy the pleasant look of our blackwater tanks we can't ignore the fact that the fishes also enjoy it as well. 

You see, blackwater tanks help fish to leave healthy because it gives the ambiance of their natural habitat. This type of biotope also helps promote the natural color of the fish. With the blackwater's acidic condition, fish displays their natural behavior resulting to an increase stimulated breeding behavior which normally won't happen in regular freshwater aquariums. 

I hope that what you read in this article encourages you to take the challenges that come with the process of setting up a blackwater tank. 

So what's stopping you? Continue your hobby and keep your scaping going!


Leave a comment

Please note, comments must be approved before they are published