Shattering a botanical myth: An idea that I can't "leaf alone..."

As more and more of us expand into the botanical method aquarium world, it's only proper that more and more of us experiment with different things. Being both a hobby-level "power user" and a vendor of botanicals, I certainly consider myself fairly well-versed on a lot of this stuff (okay, as "well-versed" as one can be about adding "twigs and nuts" to his aquarium!).

And, like you, I enjoy a good experiment or two, particularly when it comes to trying new botanical items for use in our aquariums!

I am often approached by hobbyists who found "such and such" a tree or bush in their yard, or while on vacation in Florida, or wherever, or from some other online vendor, and ask me if the seed pods, roots, or leaves are suitable for use in aquariums. And honestly, most of the time, I give the same answer if I have not used the item in question:

"I don't know."

Well, shit. That kind

"I thought that you were some kind of expert, Scott! WTF?"

I get it.

Hardly befitting of an answer from a guy who makes his living selling botanical items for use in aquariums, I know- but it's the truth. There are around 400,000 described plant species in the world, and an average of 2,000 new species are described each year!

I'm a fish geek, not a botanist, so understanding physical/chemical/environmental impact of almost any plant is "beyond my pay grade", as they say! I can only speak in general terms, or based on my own experience with specific materials. To assert otherwise would simply be irresponsible.

Yet, I think it's time to shatter a rather monolithic "myth" of sorts that we have collectively created in our hobby sector:

"Only certain tropical leaves and botanical materials are useful in the botanical-method aquarium."


The longer that I play with botanical stuff (almost three decades now)- the more I'm starting to think that you can use just about any dried leaf you can collect in your aquariums. Of course, the "qualifier" is that the leaves should be naturally fallen and dried, having expended the sugars and other chemicals within their tissues which could contribute to water quality degradation. And it's a given that you don't want leaves from areas of known agricultural pesticide use or industrial pollution in your tank.

Oh, and of course, using leaves from plants known to be toxic to higher life forms is simply a "red line" that you just wouldn't want to cross...I mean, use some common sense here! If a plant is called "Poison___________" or "Deadly Nightshade", or something equally evil-sounding, you'd have to be a complete moron to try to use it in your aquarium! (No mincing words here)


(Poison Oak. NOT a good one for aquarium use!)

Why am I getting increasingly comfortable with this position about using all sorts of leaves? Well, for one thing, it's based on my experience and the collective experience of our global community with using leaves in aquariums. Leaves seem to "function" the same in aquariums regardless of what tree they come from. Sure, some are more durable, are different structurally or aesthetically- but they all sort of do the same thing for the tree they come from, right?

Also, so many leaves of so many varieties of plants fall into waterways all over the world that it seems unlikely that you can ONLY use Catappa, Guava, Jackfruit, etc. in aquariums. Most of those aren't even found around waterways. Rather, it's stuff like species of  Ficus, etc. that you find in the bottoms of streams and rivers in the tropics. 

( Yeah, the pervasive Ficus!)

Sure, some leaves likely have greater concentrations of tannins and other beneficial compounds than others, but I dare say that many leaves are similarly comprised, thus making them acceptable for what we do.

I mean, live oak leaves from Texas or California are just as useful and beneficial in real-world aquarium applications as Jackfruit leaves from India. They just are.

Leaves don't have to be from some exotic locale to be useful for our tropical aquariums!

"Woah! Fellman just killed the market for tropical leaves after 9 years!"

Nope, of course I didn't.

I merely said that you don't HAVE to use "X" leaves from Southeast Asia to have a successful botanical method aquarium! The past decade was fun for  experimentation with exotic leaves and botanicals, but my personal conclusion is that you don't need to buy everything from us or any vendor in order to have a successful botanical method aquarium. 


You can create amazing botanical method aquariums with what you can find locally. I'm proud of the fact that I've been saying this for years- but now it's time to really scream it out loud!

When I started Tannin, I had a good working knowledge of playing with many of these items in closed aquatic environments. Catappa (Indian Almond) leaves, for example, had been used for decades by fish people to impart tannins and other substances into the water, as had guava, jackfruit, and a few other tropical leaves.

Now, it just so happens that Catappa has been studied pretty extensively by science, and it's generally acknowledged that there are some beneficial substances contained in the leaves and bark, many of which are known generally to have potentially medicinal properties.

Now, keep in mind that these substances are present to protect the tree from fungi, bacteria, and parasites, so it's likely a bit of a leap when aquarists immediately extoll the virtues of them as "fish remedies." However, flavonoids, such as Quercetin and Kaempferol, which are apparently abundant in Catappa leaves, are known to have anti-inflammatory and possibly even anti-cancer affects, and anecdotally have been determined to be beneficial to fishes.

I actually did come across a laboratory study from the Fisheries Ministry in Malaysia that determined catappa extract to be useful as a remedy and/or prophylactic for some fish diseases, so that vindicated some of the "anecdotal" stuff, in my mind.

Yet, you see tons of vaguely-worded "articles" on the purported "medicinal" properties of Catappa, typically on websites that, well- sell the leaves. And often, they're "muddy" and filled with wonderful marketing hyperbole and claims about their "powers"-all of which serve to simply compound the myths that are unfortunately so abundant in the aquarium world about botanical materials.

And I can't help but wonder- are there other, not-so-"exotic" leaves out there around the world that have similar properties? I'll be that there are- it's just that no one has really gotten around to testing them!

Could it be that the main reason that these seemingly exotic leaves from Southeast Asia and other places have been used for decades in aquarium work is because they were simply the most abundant leaves available to adventurous and resourceful hobbyists who resided in those locales?

I think so.

I mean, if these adventurous souls resided in Cleveland instead of Bangok or Malaysia, would Ash, Oak, Beech, or whatever leaves are abundant in the local forests be THE leaves we use in aquariums?

The mind wanders...

Does every dried leaf from every tree in Nature have some degree of these, or other "medicinal" compounds?

I don't know for sure. I think so, but I can't really say with certainty. I honestly don't know who does. It'd be pure speculation to make this leap, right?

We steer clear of this kind of vagueness, and rather, choose to focus on their use as an ecological base for beneficial microfauna, as aquascaping materials, and as a means to impart tannins and other substances from their tissues into the aquarium water, creating the visual tint and possibly impacting some of its environmental parameters.

Those things are typically not disputable, with the exception of to what extent they do this.

However, personal experience with a wide variety of botanical materials from around the world has made me question the "micro-dogma" we have in our sector that you absolutely HAVE to use certain tropical species of plant materials to get these effects.

Yes, I've spent the better part of three decades seeking out the most exotic botanical materials I could find, all over the world, and I've come to the rather generalized conclusion that you can essentially get the same effect in your aquarium with locally or domestically-sourced materials as you can with exotically-sourced tropical materials.

In the end, the differences may simply be more about form than function.

Sure, some just look more exotic. Some DO come from regions where our fishes hail. Some are perhaps more "regionally biotopically appropriate" than others...but in the end, most any botanical (with the caveats discussed above about toxins- and care for where/how they are collected) will accomplish the same damn thing in your aquarium.

What ARE we trying to accomplish with botanicals in our systems?

Well, we're trying to create a "substrate" for an underwater ecology- a place for fungal growths, bacterial biofilms, and other microorganisms to colonize and create the basis of a food web and a biological "filtration" system. We hope to take advantage of some of the tannins and other compounds bound up in the botanical materials to impact water chemistry as well.

And it doesn't take a "Pongo Pongo leaf" from Malaysia or a "Buganki Pod" from Borneo to do that!

It just doesn't. 

Some of the best and most successful botanical method aquariums I've ever created utilized decidedly "un-exotic" oak twigs and oak leaves! 

Botanists will tell you that most trees and plants have leaves, bark and seed pods which contain tannins and other substances. And of course, these can impact the environmental parameters of aquatic environments when submerged or steeped in water. To what extent, may only be determined by careful field/laboratory analysis- something most of us are simply not equipped, educated, or prepared to do.

Some materials may prove toxic to aquatic and other animal life if consumed, steeped, or otherwise utilized in the aquarium.  Fact.

I can't tell you if that cool seed pod you found on holiday in Ibiza or on your hiking trip in The Appalachians is going to "nuke" your Geophagus tank.

I can only tell you how I'd approach how to find out about it: Try to research what you can (there's this crazy cool site, g-o-o-g-l-e, and they have all sorts of information you can look up!), and...experiment...with what you consider "expendable" (gulp- I cringe even saying that...) fishes in a reasonably controlled setting.

Yeah, "experiment."

Risk. Chance. It's not for everyone, but if you want to use "any old seed pod" or leaf, you'll need to experiment for yourself to know for sure. Someone has to be first to taste the metaphorical "berries", and sometimes, they might be deadly.

As I've told you for years, every single botanical item which we offer has been tested- and fairly extensively- in our own aquariums, and in those of some of our friends- with our own precious fishes. It's the best way to know for sure, IMHO.  We didn't just wake up one day and decide to create a business because we found some cool acorns in a tree down the street. We spent years playing with this stuff.

And guess what? We've killed a few fishes- very few- along the way. It sucked. But we have killed some. And it wasn't just because the botanicals used were somehow "poisonous" was usually because we pushed it, in terms of numbers of stuff added, using the materials without preparing them, or just added too much too quickly. Even with "safe" stuff, as we've discussed many times here- you can push too hard too fast, and create potentially tragic outcomes for your aquariums. 

There is a technique to using botanical materials in aquariums. A process.

You have to prep them, add them slowly, and observe carefully.

We say this over and over to the point where you're probably sick of hearing it- but we'll keep saying it. No matter what you use, where you obtain it from- or what anyone- even myself- says. Every aquarium, every fish, every situation is different, and the possible outcomes are always subject to lots of variables.

Even "proven" natural materials can sometimes still  have unpredictable results. Because, ya' know- Nature. We're not entirely in control here.

It's as simple as that.

Anytime you add anything to your closed aquatic environment, "stuff" can happen. It's reality, as you know. Some fishes, like Apistos, Bettas, and some Characins, are very sensitive to even minute changes to their environment, and even with "safe" botanicals, you need to go slowly when adding them to an established aquarium.

Our "best practices" about what to use and how much to use have been developed in our community for many years now. Now, after a while, like anything else in the aquarium hobby, you sort of get a "feel" for what can and cannot work with botanicals.

You'll sort of look at a seed pod, leaf, or whatever, and have a sort of hunch, test them, and be very pleasantly surprised. Other times, you'll be shocked that the seemingly innocuous leaves you just added to your test tank have the fishes gasping at the surface. You just can't be sure until you test it yourself. 


Don't want the risk? 

Don't play with botanicals in your aquariums.

Simple as that.

That being said, if you're fortunate enough to have a nice oak tree nearby, for example, go for it- collect and test those leaves, and if they are not harmful, use them in your aquariums! Chances are, they'll be totally fine. This is the fun part of playing with botanicals! There is a lot of "DIY" potential here.

But you have to take the risk. 

(White Oak. Pic by Msact, used under CC BY-S.A. 3.0)

And remember, it's not all about getting the "coolest stuff" for your tank. It's not just about creating a cool "look"- although that is a collateral benefit which we all appreciate.

It's about learning and observing and appreciating what botanical materials can do in your aquarium, and how they can form the basis of your underwater ecology.

After my little "sabbatical" that I've taken from being active in the business of Tannin, it's just become a lot more clear to me that we (by that I mean vendors and hobbyists) are often placing too much emphasis on the acquisition of "stuff"- in our case, materials with exotic names and some sort of "cachet" within our niche, as opposed to understanding and celebrating the "craft" of what the botanical aquarium movement is all about. 

One of the most amazing things about our practice of adding leaves, twigs, seed pods, snd other botanical materials to our aquariums is that they can be almost "relied on" to perform in a fairly predictable manner in our aquariums.

The same natural processes which affect the decomposition of an Alder Cone from Europe impact the Sterculia pod from Southeast Asia, the oak twig from North America, the Jackfruit leaf from Malaysia, or the Banana Stem from Thailand. Colonization by biofilms, fungal growths, and the resulting decomposition which occurs are the same all over the planet.

And they're the exact same processes which govern what happens in our aquariums.

Think about that for just a second. 

We receive a LOT of questions from our community, asking what botanical is suitable for a tank intended to represent a specific environmental niche or geographic area. The answer isn't always as simple as "use this leaf" or whatever.

The reality is more nuanced, really.

We should understand conceptually that the way Nature functions is the same, regardless of what materials you're using to do the job. I know, I'm being redundant here...

However, it's a really important point, specifically for those of you who are just hell-bent on assuring yourself that every leaf, twig, and seed pod in your "Southeast Asian-themed aquarium" is, indeed from Southeast Asia! NEWS FLASH: It doesn't have to be.

Yeah, unless you live in the area that you're trying to represent in your tank, or are really dialed in to a good supply of whatever botanicals are native to that region, you're almost going to have to use stuff that's largely representative of what comes from there.

And that's just fine. Really.

Often, I'll come up with an idea for the aquarium representation of a unique niche habitat, and will spend a lot of time researching the ecology and, more important to me- the function of  the habitat, before embarking on my project. 

And yeah, more often than not, I'll find that the plants, wood, leaves, or whatever that I need to really nail the project in a a full-on "biotopic manner" are simply not available to me.

And guess what? That's okay. I don't "get stuck." 

I just don't get stressed-out about it.

You shouldn't, either. Contest entries be damned.

I'll bet that there are less than a handful of experts in the world who judge biotope aquarium contests who could even make positive identifications of the leaves used in many entrants' aquariums...especially after said leaves have been submerged for a while, have started to soften, and have recruited a "patina" of biofilms and fungal growths.

So don't stress out over this.

Yeah, I receive a lot of emails from fellow hobbyists who are "stuck" because they can't find leaves or seed pods from "that" exact plant...And so they dramatically change, or even abandon their projects as a result.

A real shame.

A suggestion, if I may?

Look for some sort of analog.

Now, sure, anyone can make dozens of arguments for why a serious biotope aquarium should have only stuff from the given region, but we'd be lying to ourselves if we expected everyone to comply with this dogmatic POV. Practicality has to reign sometimes. You simply can't get every single leaf or seed pod that is found in any given geographic area, for all sorts of reasons. I mean, you certainly should try if that's your thing- we do...and it's a kind of fun pastime for some of us!

However, let's keep it fun. 

And speaking of fun- please don't get swept up into the "hype machine" that's already forming around our little hobby sector in social media and elsewhere.

I don't want this hobby niche that I've helped play a small part in creating to become what the reef aquarium hobby is now- an endeavor dominated by the marketing and acquisition of over-priced, diminutively-sized, exotically-named "collector coral frags."

The thought of  a proliferation of botanical vendors trying to "one-up" each other on social media, with ever more exotically-named and higher-priced items (which, in reality, are often the same stuff everyone else offers, or offer little advantage to what's already available, other than they're "new" and from some other exotic locale!) frightens me.

The "'gramification" of our sector has begun in earnest. 

It makes me want to vomit.

I sold my interest in my coral business a decade ago after coming to that very realization about that hobby sector. I didn't want to be involved in the dismantling of the enjoyment of the reef aquarium hobby. I don't want that to happen with the botanical movement.

The aquarium hobby is expensive, but I don't think that our little sector needs to be. Creating "cachet" around certain natural materials is kind of weird, isn't it? And yeah, I think that I am partially to blame for that, and I'm gonna put a stop to my participation in making it that way.

I absolutely hate it when I get an email from a potential customer talking about their planned botanical-method aquarium that starts with something like, "...and when I save up enough to order some ________ pods from you, I'll start this tank!"

Shit. That sucks.

Sure, stuff costs money, but the cost of the botanicals themselves shouldn't be the primary barrier to entry for starting your next botanical method aquarium. I'm not going to contribute to the creation of said barrier. Yes, stuff costs money, but the value is what we perceive it to be. 

The reality is, we collectively have to place a greater emphasis on technique and processSharing our successes and our failures. So that we can all learn from them

And, on a personal note...a "mea culpa" of sorts:

I've struggled mentally with this tension between hobby and business of late...and I've done a terrible job at managing it. In addition to taking on a distracting side project, I stepped away a bit for my own health, leaving many of you wondering WTF was up. I handled this extremely poorly. I'm very sorry for this, and I'll make it right for all of you. Please be patient if you can.

As Tannin re-emerges from its "hibernation" (Much more on this in a later installments of "The Tint"), I'm going to double down on what got us all here: The sharing of ideas, discoveries, processes, and techniques. Building a community of adventurous, bold, like-minded hobbyists. Not simply trying to bring in more "stuff" to sell and create a "high-end" market for.

I don't intend, need, or want to do that. I never did, but I saw that it was heading in that direction, to be honest. Tannin got big- a little too big for what I intended, really. I didn't like it. Something had to give. I had to "break" or it would break me mentally. 

Change is coming.

Now, this doesn't mean we'll quit offering botanicals, or new stuff. It doesn't mean that I'm against selling stuff or making money or growing the company in a positive way.

It simply means that we're going to place emphasis on what's really needed right now: Sharing the ideas behind this stuff. More of that. Offering materials that will help you get there, without continuously trying to "one up" ourself or other vendors, by seeking to offer every type of botanical material available. Been there, done that. Let them have that headache!

We'll be offering some "staple" items of our craft; stuff that we love to use ourselves- and try to keep pricing reasonable, while still reflecting the operating costs associated with what we do.Yeah, when I stumble across something interesting, I'll make it available as I can source it.

I want to continue to make Tannin the "clearinghouse" for information on the botanical-method aquarium, rather than the source for buying everything.  A much more "personal" business. I want to have fun again. I want YOU to have fun, while being able to afford to do more. A "win-win."

We'll talk more about collecting your own stuff, using what you've got already- and directing you to alternative sources to find some of the materials that we can utilize in our botanical method aquariums. 

We will continue to offer and develop our "NatureBase" substrate line, since so many of you really have enjoyed the product, and since I love playing with and developing them! And we'll talk more about how substrate materials work in the botanical method aquarium. And yeah, I'll even share a few "recipes" for making your own similar substrates!

And sure, because I just can't help myself, I'll still try to develop some more "ecology-based" products, to help foster the microbiome that's so important to our work.

In the end, it'll be all about sharing the craft- the love- that we have for this crazy cool aquarium hobby sector.

It's been an 8 year ride. A lot has happened. A lot is yet to unfold. And the most exciting thing is that it feels like I'm just getting started again!

Thank you for your faith in me, in Tannin, and in the ideas we discuss here. Thanks for your interest, your passion, your patience- and your faith in the processes of Nature.

Let's continue to move forward together in a positive way.

Now, the future starts.

Stay bold. Stay dedicated. Stay curious. Stay diligent. Stay passionate...

And always Stay Wet.


Scott Fellman

Tannin Aquatics 


Scott Fellman
Scott Fellman


1 Response

Florian Preissler
Florian Preissler

April 20, 2023

I fully agree – once heard a German podcast in which a scientist from the Humboldt University Berlin confirmed pretty much everything you said.
According to him you can use every dried, non-toxic leave (even dried fallen of pine needles) to put in the aquarium directly or make an infusion from it.
Shouldn’t use ornamental shrubs though, better to stick with native plants you know about.

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