Startups and evolutions...

I'm in a sort of "startup mode" with some new aquariums in my home office...And it's been quite a while since I actually set up some tanks. These aquariums are some  smaller ones, being set up in a corner of my new home office before I set up my larger ones. These are sort of "test beds" for some of the theories, ideas, and products that we'll be working with in the weeks and months to come. 

Right now, I'm really playing with my idea of creating aquariums from a terrestrial phase and working them into an aquatic phase over a longer period of time, building up the biome via leaf litter and bacterial inoculation, then adding the fishes after a longer period of time. This is stuff we've talked about here for a while. 

When you play with some of the ideas that we do-like utilizing sedimented substrate materials, leaves, and other materials, right from the start, you have no choice but to embrace some unusual and perhaps unpopular aesthetics, like dark,  turbid water, biofilms, and fungal growths.

I've long been a fan of soaking wood prior to use, for the purposes of saturating it so that it may sink, and perhaps leach out any surface impurities. Lately, however, I've found myself typically giving my wood pieces a good rinse and a scrub with a soft brush, and then placing them in my aquariums. What this yields, of course, is not always pretty: Cloudy water, more of a darker tint, and almost immediate growth of biofilms and fungal growths o the wood surfaces.

So, why the hell would I subject myself to these things? Well, to begin with, because I believe that we as aquarists have operated under the assumption that it's a good idea to exclude as much organic material from our aquariums as possible, and also, as you know, aquascspaing forums are filled with frantic please from hobbyists wondering when there wood will "stop leaching tannins" into their tanks. I see this as a sort of plus!

One thing that I am fascinated by is the way our aquariums, like the wild aquatic systems they seek to emulate, transition from terrestrial habitats to aquatic ones. The "Urban Igapo" idea we've been playing with for the past couple of years now has really cemented my opinion that this is a very rational approach to creating a more durable, biologically diverse aquarium ecosystem. 

that they become the basis for biological activity in the tank. As we have discussed a million times here, as botanicals break down, they recruit bacteria, fungi, and other organisms on their surfaces.

What I am starting to feel more and more confident about is postulating that some degree of denitrification occurs in a system with a layer of leaves and botanicals as a major component of the tank. At the very least, good nutrient processing occurs in such a system because of the resident micro and microfauna present in this botanical bed.

Now, I know, I have little rigorous scientific information to back up my theory, other than anecdotal observations and even some assumptions. However, there is always an example to look at- Nature. 

Our ability to mimic this aspect of the flooded forest habitats is a real source of benefits for the fishes that we keep- and a key to unlocking the secrets to long-term maintenance and husbandry of botanically-influenced aquariums.

The transformation of dry forest floors into aquatic habitats provides a tremendous amount if inspiration AND biological diversity and activity for both the natural environment and our aquariums.

Of course, Nature and aquariums differ, one being a closed system and the other being "open." However, they both are beholden to the same laws, aren't they? And I believe that the function of the captive leaf litter bed and the wild litter beds are remarkably similar to a great extent.

The thing that fascinates me is that, in Nature, leaf litter beds perform a similar function; that is, fostering biodiversity, nutrient export, and yes- denitrification.   Now, that's not exactly a hug stretch, I realize. However, I'm starting to think about another idea...The idea of running a botanical-style aquarium without supplemental filtration of any kind is appealing to me; not "just because"- but for the idea of how they can efficiently process/sequester nutrients.

On my ADA 60F, a long, shallow tank, I am incorporating a surface-skimming, and perhaps a very small (perhaps even undersized) outside power filter to remove some of the initial debris which end up in aquariums from time to time after terrestrial materials are first submerged.

I've postulated the idea about botanical/leaf litter beds functioning as a sort of biological filter, and I think it's pretty much a given that these systems do indeed perform that role. I believe that it's not only possible- but probably very efficient- to utilize the materials in the botanical/litter bed to foster denitrification.

I believe that the idea of embracing some of the things that we’ve feared- like having all of that fungal growth on new wood, understanding the turbidity and cloudy water, and accepting the fact that things will evolve past the early, perhaps unsettling aesthetics. “Pushing through” the earliest phases. When you think through the idea of how these early impacts are mostly aesthetic, you start to realize that the looks of this stuff is actually more awful than any possible detriments that they bring.

Utilizing our friends, the bacteria- the biofilms, and the fungal growths- to work with us to create amazing, functional systems is irresistible and more achievable than ever before.

And, if we can make that mental shift once again, which says that “looks aren’t everything”, we open ourselves up to pouching beyond previous limitations which have been part of standard hobby “doctrine” for generations.


Keep pushing. Right from the start.


Stay diligent. Stay curious. Stay open-minded. Stay bold…


And Stay Wet.



Scott Fellman

Tannin Aquatics 




Scott Fellman
Scott Fellman


2 Responses

Scott Fellman
Scott Fellman

October 14, 2020

Hi Matt,

Absolutely worth experimenting with. I’ve been doing numerous iterations of my “Urban Igapo” tank for a while now with great results. I’ve used everything from terrestrial grasses to Cryptocoryne, to Bamboo, and Across, and other stuff. It certainly will work for your Southeast Asian theme. Do a search on our site for more articles o the topic. Here are a couple to get you started:

Hope these help. You can do a search on “Igapo” and similar topics here and find a lot of my ramblings…and on the Tint podcast, too.




October 14, 2020

After listening to several of your podcasts, I too have been playing with the idea of a “seasonal” tank. My idea is to create a terrarium planted with a mixture of plants that would live or die if flooded. So for example, i would start some pothos and mondo grass. Then once these plants appeared to be established I would start flooding the tank. In my experience the pothos vine would continue to grow filling the tank with roots. The mondo grass (which is mistakenly sold as an aquatic plant at the big box stores) would eventually die. I would have twigs, leaves and extra that I would allow to float and then most would probably sink. Which I recently have realized is an unused area of scaping. Nature is full of floating twigs and leaves. Not everything has to sink. I have not decided on what to stock it with. Fish? Crustaceans? Snails? To take it a step further I would try to follow the season of a particular area. In this case SE Asia.Adding water when the rainy season began, topping off during and then stopping when the dry season kicked in. Then allowing the tank to evaporate until the terrarium returns. I would probably use no tech other than a light. The livestock would be removed when the water level receded too far to support them. Would it be possible to have seasons plants that would return when the water dried up? Or vice versa? Perhaps Java moss that could survive both ways? Just some thoughts triggered by tannin.

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