Beyond the tint: Clearing the waters about botanical-style aquariums...

With the explosion of interest in botanical-style aquariums, there has been a tremendous influx of aquarists who have never worked with stuff like leaves, seed pods, and twigs in their tanks before. It makes a lot of sense; we've been told for a generation that these things can create environmental conditions in our aquariums which might challenge our abilities to manage them safely. 

Now, I've spent the better part of the last two decades doing all sorts of crazy experiments with botanicals, and all of the past 5 or so years evolving Tannin Aquatics and advancing the "state of the art" of the botanical-style aquarium approach in general. It's been a very gratifying several years. 

Yeah, I love the natural, botanical-style blackwater/brackish aquarium. I'm totally obsessed with utilizing botanicals in all sorts of cool aquariums! They look amazing, create a functional ecosystem for all sorts of fishes- and are utterly incapable of doing everything that we seem to want them to do!

Yep. That's correct.

With all of the cool tanks we're seeing coming up, and a growing global interest in blackwater, botanical-style aquariums, we're seeing a lot of discussion about the "functional" aspects of botanicals. Perhaps most astonishingly, we see self-proclaimed, yet likely well-intentioned "experts" (many of whom simply have not worked with these types of systems before personally) ascribing all sorts of characteristics to them, and alternatively proferring unsubstantiated claims about the benefits they can provide, as well as unfounded warnings about their "dangers."

It can be a head-scratching experience perusing forums sometimes! The spread of misinformation (unintentional or otherwise) is something we have- and will continue to- work very hard to clear up. It's not simply because we sell botanicals. It's because we are on the cusp of an aquarium movement and are helping foster the development of technique for these aquariums, hoping to dispel many years of misunderstanding and mystery- for the benefit of the entire aquarium hobby.

I consider it as much of an honor as it is our responsibility.

And with all of the discussion and "armchair experts" comes more than just a little confusion, a lot of opinion, and some occasional misconceptions about what botanicals can and cannot do for our aquariums.

Yeah. Confusing.

In this little blog piece, I'd like to focus on what botanicals cannot do! 

Yeah, you heard me correctly.

Maybe I should clarify: Let's talk about what they can't do as completely as many hobbyists tend to assume that they can! We're just gonna look at four things- but these are topics which seem to come up again and again and again, so I feel there definitely worthy of a closer look!

IMOH, it's very important to clear up lingering (or emerging) misconceptions about the use of botanical materials in aquariums. Since our self-proclaimed "competitors" seem more intent on selling stuff than sharing information about it, we'll take the reins on this one yet again.

As in so many areas of the hobby, the more people become involved in the process of utilizing botanical materials in their aquariums, the more we break through and clear up some of the confusions about them...Now, it's not like anyone was intentionally trying to mislead people over the years- I think it was more of a matter of us just making lots of assumptions and drawing conclusions from widely varying sources- often with questionable validity, experience, or accuracy, or "regurgitating"  second or third hand information from tangential topics.

Not a great way to help foster a hobby movement, right?

So, let's get down to it!

In no particular order, here are some concepts that I think we need to address:

1) Botanicals cannot soften your water! If I had a dollar for every question I've fielded on this topic.... Perhaps this is the most misunderstood thing of all about botanicals? Maybe. I think it's easy to see how this one got started and tends to hang around a bit in forums and such: Most botanical materials contain tannins and humic substances, which can drive down the pH in water with little to no carbonate hardness.

 And of course, the tinted, soft acidic water in many natural habitats often has an abundance of leaves and botanicals present. I think that this gave a lot of hobbyists the impression that you could simply add some of these materials (leaves, etc.) into your tap water and create "Rio Negro-like" conditions easily!

Now sure, humic substances, tannins, and other compounds which color the water will be imparted to it when you add botanicals...

Yet, that's really only half of the story.

Botanicals cannot reduce the hardness of the water. This can only be accomplished with reverse osmosis or ion exchange ( a process in which calcium and magnesium ions are "exchanged" for sodium or potassium ions.)

Reverse osmosis is a water treatment process which relies on a membrane which has pores large enough to admit water molecules, yet "hardness ions" such as Ca2+ and Mg2+ remain behind and are flushed away by excess water. The resulting product water is thus called "soft water"-free of hardness ions without any other ions being added. 

There is no botanical, leaf, or substance you can add- natural or otherwise- directly to your water to soften it. 

And just because you toss in a bunch of catappa leaves, Alder cones, or whatever into your aquarium filled with un-altered tap water, it doesn't mean that the pH will plummet to Amazonian levels. The impact of these materials on pH is limited in water with significant carbonate hardness.

And this dovetails nicely with our next topic:

2) Tinted water is not necessarily acidic. Once again, another assumption that no doubt arose from the aesthetics of blackwater itself. And it is easy to see how it got started...Much like the misconception that botanicals soften the water, it was often assumed by hobbyists that the brownish tint imparted to the water by leaves and botanicals somehow implied that it is "soft and acidic."  I mean, "If it looks like the Rio Negro, it must be just like the Rio Negro! Right? Um, nope.

Yes, once again, there is more than meets the eye.

Botanical materials contain substances that can reduce the pH in water with low to negligible carbonate hardness. However, the tannins, which are the substances which tint the water, cannot "overcome" the Calcium and Magnesium ions, and drive down the pH significantly in water with high levels of these carbonate hardness present. It simply is putting more materials into the water (which are often detectible by TDS meters in aquariums).

Color is simply not a reliable indicator of the pH and other characteristics of the water. And, as we've discussed before, there are natural aquatic habitats, such as the Tapajos, which have essentially clear water, yet are rather soft and acidic. 

FINAL THOUGHT ON THIS TOPIC:  If you want to create soft, acidic blackwater conditions with botanicals, you need to invest in a reverse osmosis/deionization unit, or use RO/DI water in your aquarium. 

Okay, moving on to our final common misconception...

3) Catappa leaves can "cure" fish diseases. Well, this is one of the favorites which has been perpetuated for years (often by people who sell leaves online and elsewhere -hey, I'm in that group, huh?)- and it actually has some degree of validity to it. However, it's not a damn "cure all"- please get that out of your head once and for all. 

It has been known for many years by science that botanicals like catappa leaves (and others) have substances in their tissues which do have some potential medicinal functions, like saponins phytosterols, punicalagins, etc.  Fancy names that sound really cool- and these are often bounced around on hobby sites as the "magic elixir" for a variety of fish ailments and maladies.

Now, I can't entirely beat the shit out of this idea, as these compounds are known to provide certain health benefits- in humans. and for a long time, it was anecdotically assumed that they did the same for fishes. And believe it or not, there have been scientific studies that show benefits to fishes imparted by substances in catappa and other leaves.

I stumbled across a University study conducted in Thailand with Tilapia  which concluded  that Catappa extract was useful at eradicating the nasty exoparasite, Trichodina, and the growth of a couple of strains of Aeromonas hydrophila was also inhibited by dosing Catappa leaf extract at a concentration of 0.5 mg/ml and up. In addition, this solution was shown to reduce the fungal infection in Tilapia eggs!

And it is now widely accepted by science that humic substances (such as those present in Catappa leaves and other botanicals) are thought to have a wide range of health benefits for fishes in all types of habitats. We've covered this before in a great guest blog by Vince Dollar, and the implications for the hobby and industry are profound. Although they are not the "cure all" that many vendors have touted them as, leaves and other botanicals do possess a wide range of substances which can have significantly beneficial impact on fish health.

It's long been known that fishes from many blackwater environments seem to have relatively little resistance to many diseases present in aquariums when first imported. Anecdotally, a lot of fish importers and breeders report better acclimation periods and fewer losses of "blackwater-origin" fishes when held in aquariums which utilize catappa leaves and other botanical materials.

Coincidence? I don't think so. "Cure-all?" Definitely not.

Now, I would definitely say that utilizing botanicals and leaves in your aquarium can offer some potential health benefits to your fishes. However, once again, I'd stop well short of presenting them as some sort of "magic elixir" that can cure fish diseases with the reliability of a round of antibiotics, or whatever. 

Rather, I think that there are some possible prophylactic health benefits for your fishes by utilizing these materials in the aquarium. I would not, however, utilize leaves and botanicals in aquariums as the sole means of curing or preventing  fish diseases. However, in my opinion, when fishes are kept in a botanical-style aquarium in which other basic components of aquarium husbandry (ie; regular water exchanges, careful stocking, and good overall maintenance) are employed, they could provide a more healthy overall environment for many species of fishes.

4) Botanical-style aquariums are difficult to manage. As botanical materials decompose in the aquarium, they degrade the water quality. This is another popularly-embraced idea which I can't entirely brush off, because there is some validity to it, and it would be itotally rresponsible of me to dismiss it outright. This sort of goes hand-in-hand with our first "myth", but it deserves a bit of its own discussion.

Let's face it- when you have materials of any type breaking down in the aquarium, they are part of the bioload- and that requires an appropriately-sized population of beneficial bacteria and fungi to break down these materials without adversely affecting water quality.

This is not some abstract concept, unique to our area of interest. It's a "universal constant" in aquarium keeping.

We've written about this idea many, many times here in "The Tint", and talked about the "ecosystem" aspect of working with this type of aquarium quite a bit. In addition to husbandry, part of the game is accepting- indeed, encouraging- the idea of having these "natural partners" in maintaining a healthy aquarium.

Now, that being said, it would be utterly irresponsible of us to say that you can simply add tons of stuff to an aquarium- specifically one that has been in a stable existence for some time- and not be concerned about any impact on water quality. That's part of the reason why we repeatedly plead with you to go slowly when adding these materials to an established tank, and to test and gauge the impact on your water quality.

Going slowly not only allows you time to react- it gives your bacterial and fungal population the opportunity to grow and adjust to the increased bioload. These organisms can go a long way towards creating a stable, healthy botanical aquarium environment...But they can't work miracles- and they can't do it alone. And of course, common sense husbandry procedures, like regular water exchanges, use of chemical filtration media (activated carbon, PolyFilter, etc.) give you an added layer of "insurance." A healthy dose of common sense and judgement goes a long way towards a successful outcome! 

Now, I'll be the first to state it. In fact, I will guarantee (something I rarely do) that you will kill every fish in your tank if you throw large quantities of botanicals into an existing aquarium without due regard for what they can do, how they function, and what is required of you to manage such a system. Basic understanding of the habitat your trying to replicate, the nitrogen cycle, pH, and aquarium management practice are all essential.

Don't f---k with Nature. She'll kick your ass.

Simple as that. Not pretty. But I think we can all understand that. If you're not up to the pleasurable effort of reading up on this stuff before you attempt a botanical-style aquarium, you have no one to blame but yourself when you fail.

So, pushing back against some of those long-held misconceptions about the botanical-style aquarium will hopefully encourage the uninitiated to give this whole "twigs and nuts" thing some due consideration. We as lovers of this type of system need to do our best to share the realities that we understand from personal experience, and to encourage others to give them a shot.

I can't help but reiterate once again that blackwater, botanical-style aquariums are no more difficult to set up and maintain than any other type of aquarium.

They do require understanding of what's going on and what is involved, observation, and upkeep...And, if you're not careful about following good common sense procedures, you can occasionally have a bad outcome. Shit happens- and it's not always good. That's part of the game. It's the reality of forging into new territory, but it contributes to the body of knowledge that is the aquarium hobby.

Okay, so that's my top four misconceptions about botanicals and botanical-style aquariums.

Of course, there are many others which arise from time to time- but those are "the big four" that we seem to hear about a lot. And, as we've seen, these are not entirely erroneous. However, it's important NOT to make assumptions about botancial materials, and to assume that they are "miraculous things" we can add to our tanks to do achieve smashing success.

The fact is, we still don't fully understand all of he affects- mostly good- but some possibly not so good- about the use of botanicals in aquariums. We have seen a LOT of instances of seemingly "spontaneous" (or at least, rather rapid) spawnings of fishes which have otherwise eluded the aquarists' efforts- shortly after introducing botanicals to their tanks.

Is this a result of some "substances" present in the botanicals? Is it a lowering of the pH in a softer-water aquarium? IS it those humic substances? Shock or some type of stress response? (!) Or could it be just a coincidence? It could be all of the above- however, I must admit that the number of times we've seen and heard this happen to us and others leads me to believe that there literally IS "something in the water!" Exactly what, of course- and how it influences these events is yet to be fully determined! 

And isn't that just the kind of stuff that keeps hobbyists coming back for more...searching, experimenting, tweaking?

Yeah, it is.

And with more "technique" than ever before starting to replace the "dump and pray" method of using botanicals in aquariums, we're seeing more and more interesting results that simply go beyond just enjoying the unique aesthetics offered by blackwater, botanical-style aquariums. We're starting to see some interesting effects on the health and well-being of many species of fishes. We're learning about the value of replicating (to some extent) the natural conditions which our fishes have evolved under for eons.

And perhaps most important- we're taking a good, long look at many aspects of these precious- and often endangered- natural habitats. This search for knowledge and appreciation of nature will not only benefit the hobby, but quite possibly the ecosystem of our home planet, as we gain a better understanding of the dynamics of blackwater habitats and the need to preserve and protect them as havens of life.


Oh, and we're having some FUN, too!

We're learning...together.

Breaking through the barrier of assumptions, hyperbole, misconceptions, and fluff that has often clouded this tinted world before we all came together and made a real effort to understand the function as well as the aesthetics of this dynamic, engrossing environmental niche. 

Keep sharing your experiences- both good and bad.

Stay studious. Stay excited. Stay open-minded. Stay skeptical. Stay resourceful. Stay careful...

And Stay Wet.


Scott Fellman

Tannin Aquatics 


Scott Fellman
Scott Fellman


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