So, what are the benefits of a "blackwater" aquarium?

We love talking about the "blackwater" environment and its affect on fishes.

But beyond the sexy aesthetic, we're talking about some real possible health benefits. Tannic and humid acids found in natural materials which break down and produce blackwater are known to have some anti-fungal properties, as theorized for many years by Betta breeders in Southeast Asia, who claim that their fishes heal up quickly from skin infections when exposed to "blackwater."

The lower pH in "blackwater" also coincides with lower concentrations of heavy metals in the water, and reduced sodium, magnesium, potassium, and calcium concentrations. As you might suspect, there are far less snails and other aquatic crustaceans found in blackwater systems than in other bodies of water, and less in the way of aquatic plants.

 From a faunal standpoint, rotifers- an important food for young fishes- are quite abundant in "blackwater" systems. And fish abundance is high- the Rio Negro, for example, has a very high number of species, with around 700 fish species documented in the river basin,  including almost 100 endemic species of fish! Some of the most popular and important fishes in the aquarium trade, such as the Cardinal Tetra, come from this region.

In the aquarium, "blackwater" provides other benefits, such as reduced algal growth, more vibrant color in fishes from this environment, and a more natural representation of their biotope of origin. From a "fun" standpoint, the creative possibilities are endless here!

With so much emphasis placed on providing our fishes natural conditions, it's the perfect time in the hobby for us to start experimenting more by creating some beautiful representations of this unique environment. The opportunity to gain insight into the behaviors, health, and reproductive habits of fishes from this rich ecosystem is too irresistible to pass up!


Consider a "blackwater" system for your next aquarium project! We have the materials, ideas, and inspiration to help you embark on this fun journey of aquatic discovery! It's a great opportunity to try something a little different than what you're used to...And isn't that part of what the tropical fish hobby is all about?

Stay Wet!


Scott Fellman

Tannin Aquatics 



Scott Fellman
Scott Fellman


3 Responses


December 17, 2020

I started a 36 gallon bow front tank 3 weeks ago. There are two large pieces of mopani wood plus some botanicals I purchased from you. The water is a rich brown color and really enhances the appearance of both the aquarium and the neons in there. My next project is to renovate my 60 gallon tank. Now it houses giant danios, gold skirt tetras, and peppered cories. I’m going to donate those to a local aquarium store, clean the tank, and start building a blackwater tank. I will be purchasing more botanicals from you, and any suggestions you can offer will be appreciated.

Scott Fellman
Scott Fellman

December 15, 2018

Oh, man, the $1,000,000 question! It’s SOO subjective…I like tetras; others liek Anabantoids, Rasbora, Barbs…Gouramis, Plecos…a ton of possibilities! I think it’s really all about researching a fish you love and going for it!



December 14, 2018

Hey guys, I’ve loved everything I’ve bought so far. It’s perfect for my blackwater tank and healthy for the fish as it’s helped heal a fungal problem my angelfish had within a couple days. I was just wondering what the most aesthetically pleasing fish would be in a blackwater aquarium in your opinion.
Thanks again!

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