Tangled twigs and dynamic processes...

Hey there, thanks for hanging in with us. Midway through our "logistical stand down" this week, and things are going well. Yeah, there's going to be a lot of shipping next week. Again thanks so much for your patience!

I thought I'd put down some quick thoughts today on a topic I love: Alternative substrate materials. Particularly, stuff like twigs, leaves, and the like. I was looking at one of my tanks the other day and it hit me how happy the fishes seemed, poking and grazing through the bed of broken twigs and leaves that makes up the majority of the substrate in the tank.

To me, beyond the simple aesthetics. Yeah, a tank 'scape in this manner (we jokingly call it a "no-scape") has a different look. And a function which is significantly different than what we're used to. And of course, I find the function part equally- if not more- fascinating than the aesthetic part.

It's very much a representation of what we see in Nature. And to our fishes, it's what they're evolved to exist in.

And our fishes take to aquariums set up to recruit biofilms easily. And guess what, not only do you ultimately learn to love the look (well, geeks like me do!), you begin to notice the incredible stability of an aquarium managed with what I half-jokingly call an "active substrate" (to borrow a term from our vivarium friends...).

Obviously, the key to the "functional" part of a "substrate-centric" aquarium is...wait for it- the substrate materials you use!

I like little twigs and root pieces. I think that when laid down loosely on the bottom of the tank (with or without a thin layer of sand), these materials serve as a sort of "matrix" to capture detritus, foster microorganism growth, and facilitate the growth of our new BFF's, biofilms!

Yeah, those guys again.

Biofilms form when bacteria adhere to surfaces in some form of watery environment and begin to excrete a slimy, gluelike substance, consisting of sugars and other substances, that can stick to all kinds of materials, such as- well- in our case, botanicals.

Biofilm growth occurs rather quickly, too.

It starts with a few bacteria, taking advantage of the abundant and comfy surface area that leaves, seed pods, and even driftwood offer. The "early adapters" put out the "welcome mat" for other bacteria by providing more diverse adhesion sites, such as a matrix of sugars that holds the biofilm together.

Since some bacteria species are incapable of attaching to a surface on their own, they often anchor themselves to the matrix or directly to their friends who arrived at the party first.

Sorta sounds like a Facebook group, huh?

(The above graphic from a scholarly article illustrates just how these guys roll.)

And we could go on and on all day telling you that this is a completely natural occurrence; bacteria and other microorganisms taking advantage of a perfect substrate upon which to grow and reproduce, just like in the wild. Freshly added botanicals offer a "mother load"of organic material for these biofilms to propagate, and that's occasionally what happens - just like in Nature.  

Yet it does, so we will! :)

The real positive takeaway here: Biofilms are really a sign that things are working right in your aquarium! A visual indicator that natural processes are at work.

Yet, understandably, it may not make some of you feel good. Again, I ask you to make a mental shift to accept them as a perfectly natural occurrence, which is ubiquitous in the natural habitats from where most of our fishes hail.

Ecologically, the productivity and diversity of these habitats make them perfect subjects for replication in our aquariums. Not only do they offer unique aesthetics- they offer really cool opportunities to see how they canfunction in a closed system like an aquarium!

When fishes are kept in a representation of a habitat which mimics its form and function, enormous potential for discoveries and success present themselves!

Look at the way rocks, soil and branches come together in flooded forests to form interesting physical spaces that fishes utilize for protection, foraging, and reproduction. By happenstance, these formerly terrestrial features become important and unique underwater microhabitats that fishes can exploit for food, protection, and spawning sites.

By replicating the complex look and physical attributes of these features, including rich substrate, roots of various thickness, and leaves, we offer our fishes all sorts of potential microhabitats. In the aquarium, we tend to focus on the "macro" level- creating a nice wood stack, perhaps incorporating some rock- but we seldom see the whole picture allowed to come together in a more natural way.

I've always been a fan of in my aquarium keeping work of allowing Nature to take its course in some things, as you know. And this is a philosophy which plays right into my love of dynamic aquarium substrates. If left to their own devices, they function in an efficient, almost predictable manner.

Nature has this "thing" about finding a way to work in all sorts of situations.

And, I have this "thing" about not wanting to mess with stuff once it's up and running smoothly... Like, I will engage in regular maintenance (ie; water exchanges, etc.), but I avoid any heavy "tweaks" as a matter of practice. In particular, I tend not to disturb the substrate in my aquariums.

A lot of stuff is going on down there...

Amazing stuff.

Even in "non-planted" aquariums, playing with this stuff opens up a whole new area of aquarium "exploration."

Like any dynamic habitat, the "botanical-style substrate" relies on a variety of organisms to do the job of processing nutrients. A healthy and diverse assemblage of organisms dwelling in this layer, ranging from bacteria to fungi too worms and small crustaceans comprise what we call the "infauna." Essentially, the infauna is a collective of organisms which do most of the work in keeping a botanical-style aquarium functional and healthy.

Be kind to your substrate, and it will be most kind to you.

Trust me on that. 

There's a lot more to the bottom than a pile of clean white sand...that's for sure!

Stay creative. Stay bold. Stay curious. Stay patient. Stay focused...

And Stay Wet.


Scott Fellman

Tannin Aquatics 


Scott Fellman
Scott Fellman


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