The "fungal filter?"

You saw the title.

What exactly am I talking about here? 

 

 

Today, I want to double back and talk a bit about our gooey friends, the fungi- for just a few minutes. Despite their off-putting appearance to some, they may be among the most beautiful, elegant, and useful organisms we encounter in the aquatic world.

Why do I have such devotion to organisms which most of us find truly revolting in appearance? 

Because they are among the most important and useful organisms which we can have in our botanical method aquariums. Think about how they arrive in aquatic ecosystems, what they consume, how they derive nutrition, and what they do for the overall ecosystem.

As everyone knows, when you put stuff in water, one of four things seems to happen:

1) Nothing.

2) It gets covered in a gooey slime of fungal growth, and "biofilm."

3) It starts to break down and decompose.

4) Both 2 and 3

Now, it's pretty much a "given" that any botanicals or leaves that you drop into your aquarium will, over time, break down. Wood, too. And typically, before they break down, they'll "recruit" (a fancy word for "acquire') a coating of some rather unsightly-looking growth. Well, "unsightly" to those who have not been initiated into our little world of decomposition, fungal growth, biofilms, tinted water, etc., and maintain that an aquarium by definition is a pristine-looking place without a speck of anything deemed "aesthetically unattractive" by the masses! 

So, with that little explanatory passage out of the way, let's take a closer look at fungi-the stuff that you'll see covering the leaves, botanicals, and wood that you place into your aquarium, and why you actually WANT the stuff there in the first place.

The fungi known as aquatic hyphomycetes produce enzymes which break down botanical materials in water. Essentially, they are primary influencers of leaf maceration. They're remarkably efficient at what they do, too. In as little as 3 weeks, as much as 15% of the decomposing leaf biomass in many aquatic habitats is "processed" by fungi, according to one study I found!

Aquatic hyphomycetes play a key role in the decomposition of plant litter of terrestrial origin- an ecological process in rain forest streams that allows for the transfer of energy and nutrients to higher tropic levels. 

This is what ecologists call "nutrient cycling", folks.

These fungi colonize leaf litter and twigs and such soon after they're immersed in water. The fungi mineralize organic carbon and nutrients and convert coarse particulate matter into fine particulate organic matter. They also increase leaf litter palatability to shredders, which helps facilitate physical fragmentation.

Fungi tend to colonize wood and botanical materials, because they offer them a lot of surface area to thrive and live out their life cycle. And cellulose, hemicellulose, and lignin- the major components of wood and botanical materials- are degraded by fungi, which posses enzymes that can digest and assimilate these materials and their associated organics!

Fungi are regarded by biologists to be the dominant organisms associated with decaying leaves in streams, so this gives you some idea as to why we see them in our aquariums, right?

In aquarium work, we see fungal colonization on wood and leaves all the time. Most hobbyists will look on in sheer horror if they saw the same extensive amount of fungal growth on their carefully selected, artistically arranged wood pieces as they would in virtually any aquatic habitat in Nature!

Yet, it's one of the most common, elegant, and beneficial processes that occurs in natural aquatic habitats!

It's everywhere.

Of course, fungal colonization of wood and botanicals is but one stage of a long process, which occurs in Nature and our aquariums. And, as hobbyists, once we see those first signs of this stuff, the majority of us tend to reach for the algae scraper or brush and remove as much of it as possible- immediately! And sure, this might provide some "aesthetic relief" for some period of time- but it comes right back...because these materials will provide a continuous source of food and colonization sites for fungal growths for some time!

I know that the idea of "circumventing" this stuff is appealing to many, but the reality is that you're actually interrupting an essential, ecologically beneficial natural process. And, as we know, Nature abhors a vacuum, and new growths will return to fill the void, thus prolonging the process.

Again, think about the role of aquatic hyphomycetes in Nature.

Fungal colonization facilitates the access to the energy trapped in deciduous leaves and other botanical materials found in tropical streams for a variety of other organisms to utilize. 

As we know by now, fungi play a huge role in the decomposition of leaves, both in the wild and in the aquarium. By utilizing special enzymes, aquatic fungi can degrade most of the molecular components in leaves, such as cellulose,, hemicelluloses, starch, pectin and even lignin.

Fungi, although not the most attractive-looking organisms, are incredibly useful...and they "play well" with a surprisingly large number of aquatic life forms to create substantial food webs, both in the wild and in our aquariums!

Natural habitats are absolutely filled with this stuff...It's like the whole game here- an explosion of life-giving materials, free for the taking...

Yet, we freak the fuck out about it when it shows up.

Another "mental shift", I suppose...one which many of you have already made, no doubt. I certainly look forward to seeing many examples of us utilizing "what we've got" to the advantage of our fishes! AGAIN: A truly "Natural" aquarium is not sterile. It encourages the accumulation of organic materials and other nutrients- not in excess, of course.

The love of pristine, sterile-looking tanks is one of the biggest obstacles we need to overcome to really advance in the aquarium hobby, IMHO.

Biofilms, fungi, algae...detritus...all have their place in the aquarium. Not as an excuse for lousy or lazy husbandry- but as supplemental food sources to "power" the ecology in our tanks.

And of course, as we've discussed many times here, fungi are actually an important food item for other life forms in the aquatic environments tha we love so much!  In one study I stumbled across, gut content of over 100 different aquatic insects collected from submerged wood and leaves showed that fungi comprised part of the diet of more than 60% of them, and, in turn, aquatic fungi were found in gut content analysis of many species of fishes!

One consideration: Bacteria and fungi that decompose decaying plant material in turn consume dissolved oxygen for respiration during the process.

This is one reason why we have told you for years that adding a huge amount of botanical material at one time to an established, stable aquarium is a recipe for disaster. There is simply not enough fungal growth or bacteria to handle it. They reproduce extremely rapidly, consuming significant oxygen in the process.

Bad news for the impatient.

Support. Co-dependency. Symbiosis. Whatever you want to call it- the presence of fungi in aquatic ecosystems is extremely important to other organisms.

You can call it free biological filtration for your aquarium!

GREAT news for the patient, the studious, and the accepting.

Think about this: These life forms arrive on the scene in Nature, and in our tanks, to colonize appropriate materials, to process organics both in situ on the things that they're residing upon (leaves, twigs, branches, seed pods, wood, etc.). 

Yeah, if you intervene by removing stuf-f bad things can happen. Like, worse things than just a bunch of gooey-looking fungal and biofilm threads on your wood. Your aquarium suddenly loses its capability of processing the leaves and associated organics, and- who's there to take over? 

Okay, I'm repeating myself here- but there is so much unfounded fear and loathing over aquatic fungi that someone has to defend their merits, right? Might as well be me!

My advice; my plea to you regarding fungal growth in your aquarium? Just leave it alone. It will eventually peak, and ultimately diminish over time as the materials/nutrients which it uses for growth become used up. It's not an endless "outbreak" of unsightly (to some) fungal growth all over your botanicals and leaves. It goes away significantly over time. 

"Over time."

That's "Fellman Speak" for "Please be more fucking patient!"

Seriously, though, hobbyists tend to overly freak out about this kind of stuff. Of course, as new materials are added, they will be colonized by fungi, as Nature deems appropriate, to "work" them.

It's one of those things in the botanical-method aquarium that we need to wrap our heads around. We need to understand, lose our fears, and think about the many positives these organisms provide for our tanks. These small, seemingly "annoying" life forms are actually the most beautiful, elegant, beneficial friends that we can have in the aquarium. When they arrive on the scene in our tanks, we should celebrate their appearance.

Why?

Because their appearance is yet another example of the wonders of Nature playing out in our aquariums, without us having to do anything of consequence to facilitate their presence, other than setting up a tank embracing the botanical method in the first place. We get to watch the processes of colonization and decomposition occur in the comfort of our own home. The SAME stuff you'll see in any wild aquatic habitat worldwide.

Amazing.

For those of you who MUST find some familiar comfort in established philosophy- look no further than the beloved master, Takashi Amano.  He laid down this track decades ago...

Yup. I'm channeling Mr. Amano here. 

In the botanical method aquairum, Amano's concept of embracing the Japanese philosophy of wabi-sabi takes over. Accepting the transient nature of things and enjoying the beauty of the changes that occur over time. 

Part of the game, as we've discussed ad naseum here, is to understand, appreciate, and ultimately embrace the way the aquatic environment is influenced by the fungal growths, biofilms, and decomposition which occurs when botanicals are added into our aquariums. 

Remember, your aquairum is not a pice of kinetic art. It's a miniature, closed aquatic ecosystem. Processes which occur in Nature play out daily in your tank.

Yeah, I admit, decades ago, I freaked out about seeing fungal growths in my tanks, too. I'd get a bit scared, wondering if something was wrong, and why no one else's aquariums ever seemed to look like mine. I used to think something was really wrong!

To reassure myself, I would stare for hours at underwater photos taken in the Amazon region, showing decaying leaves, biofilms,and fungi all over the leaf litter. I'd read the studies by researchers like Henderson and Walker, detailing the dynamics of wild leaf litter zones and how productive and unique they were.

I remember telling myself that what I was seeing in my tanks was remarkably similar to what I saw in images and videos of wild aquatic habitats that I wanted to replicate. They seem to look- and even function- so similarly.

I'd pour over my water quality tests, confirming for myself that everything was okay. It always was. And of course I would watch my fishes for any signs of distress...

I never saw them.

Truth be known, I knew that there wouldn't be any issues, because I created my aquariums with a solid embrace of basic aquatic biology; an understanding that an aquarium is not some sort of underwater art installation, but rather, a living, breathing microcosm of organisms which work together to create a biome..and that the appearance of the aquarium only tells a small part of the story.

 

And another big concept for you to wrap your head around:

Your aquarium- or more specificlally- the colonized botanical materials which comprise the botanical-method aquarium "infrastructure" acts as a biological "filter system."

In other words, the botanical materials present in our systems provide enormous surface area upon which beneficial bacterial biofilms and fungal growths can colonize. These life forms, like fungi, utilize the organic compounds present in the water as a nutritional source, thus creating a "nutrient assimilation process."

Understanding and embracing this has changed everything about how I look at aquarium management and the creation of functional closed aquatic ecosystems. 

It's really put the word "natural" back into the aquarium keeping parlance for me. The idea of creating a multi-tiered ecosystem, which provides a lot of the requirements needed to operate successfully with just a few basic maintenance practices, the passage of time, a lot of patience, and careful observation.

It means adopting a different outlook, accepting a different, yet very beautiful aesthetic. It's about listening to Nature instead of the "influencer" on YouTube with the flashy, gadget-driven tank and nothing substantive to back up his vapid narrative. It means educating yourself a bit. It's not always fun at first for some, and it initially seems like you're somehow doing things wrong.

But you're not. And Mother Nature won't let you down if you don't lose faith in Her.

And yeah- it's about faith. Faith in Mother Nature, who's been doing this stuff for eons. She's got this. She'll hook you up...If you allow Her. If you have faith in Her processes.

Have faith.

Stay bold. Stay thoughtful. Stay curious. Stay patient...

And Stay Wet.

 

Scott Fellman

Tannin Aquatics 

 


Scott Fellman
Scott Fellman

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