The "wood part" of the natural aquarium equation.

Pretty much every hobbyist on the planet has played with some type of "driftwood" in his/her aquarium at some point in time, right?

Yeah, I think that's a pretty accurate statement! Now, we all know that when you use driftwood, there are some steps that you need to take in order to prepare it for aquarium use. And of course, there are some expectations about what happens during the process.

There's a fair amount of misconceptions and misinformation out there about what can work and what is not safe, etc.

And a lot of misunderstanding about where and how wood in the aquarium fits into the whole "equation" of creating a functionally aesthetic aquarium habitat...

At the risk of adding to the confusion, I'll try to clear up some stuff here.

Believe it or not, if properly prepared, almost (I say…ALMOST) any type of dried wood can be utilized in aquariums. The important thing is that the wood must be…well, DRY! It can’t be “live”, or have any "greenwood" or sap present, as these may have toxic affects on fishes when submerged.

Sap can be toxic to fishes, even when dry, so if you see a piece of wood- even dry- that’s displaying some sap- it might be a good idea to remove the section where the sap is coming from, or to simply take a pass. In our experience, it’s a better idea to purchase/collect your wood from sources known to offer “aquarium safe” wood, and not worry about suitability, toxic concerns, etc.

 

"Driftwood" is sort of a generic term for wood that has been dried over time, generally free of bark, (which, other than containing tannins and polyphenols, that are largely non-toxic in reasonable concentrations- is not that problematic, actually) and "greenwood" as outlined above. In most trees, the real chemically active substances are found in the leaves, live “greenwood”, and the sap. So, a dry, largely bark-stripped piece of wood, free from sap, dried or otherwise, is generally pretty good to go, and is relatively stable and neutral.

Someone asked me if we are going to start offering (insert stupidly-named wood type here). And of course, I had to think about this for just a bit. 

It seems to me that, on any given day, such-and-such a wood type is the "IT" variety, and everyone wants it. Some guy does a tank with this scraggly shit emerging from the water, posts a few sexy pics on his Instagram feed, and the next thing you know...trend.

As someone who offers natural aquascaping materials for use in specialized aquariums, I long ago realized that I needed to stop chasing every hot type of wood that shows up on the market. I have found some types which have proven to be great to use in our natural-style aquariums. I am generally clueless on "what's hot" in the aquascaping wood world.

We'll continue to offer types of wood that we enjoy using in our own 'scapes. Some will just happen to be ones that are popular and relatively common- or even "trendy" at the moment. Some will be types which fell out of favor with the mainstream 'scaping world. Some will be obscure, niche-specific stuff. We will constantly introduce new varieties as we encounter them.

The majority, however, will simply be stuff that works.

That answers that., I hope?

Of course, that means I'm really the last guy who should be discussing what wood to use in your aquascapes. Rather, it will be a discussion on what happens at that magical moment when we place wood in water...

 

First off, let's think about where our wood comes from..

Well, shit- it comes from (wait for it...) trees.

BOOM! Minds blown, I know!

For the sake of this discussion, let's just assume that you're working with wood that's been properly collected and is suitable for aquarium use.

When you first submerge wood, a lot of the dirt from the atmosphere and surrounding environment comes off, along with tannins, lignin, and all sorts of other "stuff" from the exterior surfaces and all of those nooks and crannies that we love so much. And a piece of wood initially emersed in water typically floats, much to our chagrin, right?

And of course, there are the tannins.

Now, I don't know about you, but I'm always amused (it's not that hard, actually) by the frantic posts on aquarium forums from hobbyists that their water is turning brown after adding a piece of driftwood. I mean- what's the big deal?

Oh, yeah, not everyone likes it...I forgot. 😂

The reality, as you probably have surmised, is that driftwood will continue to leach tannins pretty much for as long as it's submerged. As a "tinter", I see this as a great advantage in helping establish and maintain the blackwater look, and to impart the humic substances that are known to have health benefits for fishes.

Some wood types, like Mangrove, tend to release more tannins than others over long periods of time. Other types, like "Spider Wood", will release their tannins relatively quickly, in a big burst. Some, such as mangrove wood, seem to be really "dirty", and release a lot of materials over long periods of time.

And it's a unique aesthetic, too, as we rant on and on about here!

What I'm more concerned about are the impurities- the trapped dirt and such contained within the wood. As you probably know, that's also why I'm a staunch advocate of the overly conservative "boil and soak approach" to the preparation of botanicals as well. A lot of material gets bound up in the dermal layer of the tree where the wood comes from. Atmospheric dust, pollutants, bird droppings, insects, etc.  None of this is stuff you want in your tank, right?

The bulk of the dry mass of the xylem (the "network" within the tree which transports water and soluble mineral nutrients from the roots throughout the plant, and comprises what we know as "wood.") is cellulose, a polysaccharide, and most of the remainder is lignin,  which is a sort of complex polymer. 

Why the botany lesson?

Well, because when you have some idea of what you're putting into your tank, you'll better understand why it behaves the way it does when submerged! In a given piece of driftwood, there is going to be some material bound up in these structures, and it will be released (gradually or otherwise) into the water that surrounds it, with a big "burst" happening on initial submersion. This is why, during the first couple of weeks after you submerge wood, that the water often becomes dark- and even cloudy.

There is a lot of "stuff" in there!

It's far better, in my opinion, to take the time to start the "curing" process in a separate container apart from the display aquarium. This is not rocket science, nor some wisdom only the enlightened aquarists attain.

We all know this, right?

It's common sense, and a practice we all need to simply view as necessary with terrestrial materials like wood and botanicals. You may love the tannins as much as I do, but I'm confident that your tank could do without those polyscaccharides and other impurities from the outer layers of the wood. The potential affects on water quality are significant!

It's pretty plain to see that at least part of the reason we see a burst of new algae growth and biofilm in wood recently added to an aquarium is that there is so much stuff bound up in it. That "stuff" is essentially "algae fuel" when added to water. Algal and fungal sports can literally "bloom" during the initial period after submersion, and this alone is great reason to take the long, slow approach to wood prep.

Interestingly, the same "process" of "curing" happens naturally when tree trunks and branches fall into wild aquatic habitats.

It's not necessarily a "quick" process in Nature, either. So, we need not feel too bad about playing a "waiting game" when it comes to curing wood for aquariums.

In fact, geek that I am, over the years I've long made it personal practice to submerge wood which I intend to use in my tank a couple of months before I set up my tank. This will enable a good percentage of the bound-up contaminants and unwanted organic materials to be released before the wood ever graces your aquascape! And it goes the wood a chance to saturate and sink, too!

Patience.

What about boiling?

Well, sure, boiling can hasten the process somewhat. But here's the deal-most of us don't have a kettle, pot, or other large enough container in which to boil a big old piece of wood, so the long-term "pre-soak" is the optimal approach. 

And let's face it, even with preparation, when you combine water, light, and organics, you're likely to get some fungus, biofilms, and even algae- for some period of time. Some fungal growth and biofilms are to be expected in the earliest days of "submersion. These tenacious life forms will exploit available nutrients and conditions that are appropriate for their survival. Just like with our botanicals, it's a normal occurrence.

Certain wood varieties, such as Manzanita, "Spider Wood", and Mangrove branches are copious "producers" of these things. Interestingly, the more "traditional" Asian driftwood tends to produce far less of this stuff. Maybe because it's been underwater for enough time to have eliminated a lot of the stuff bound up within it.

Biofilms and ... Well- we may not like the way it looks in our tanks. I totally get that.

Now, I remember deliberately NOT pre-soaking the Mangrove wood in my office tank (I love torturing myself, apparently) just to see how nasty this could be. (oh, the things I do for you in the interest of sharing knowledge!)

The result? It literally took about 4-5 months before the wood stopped producing biofilm and attracting hair algae in really large quantities.

That was freaking punishing. Well, I found it kind of cool, but pretty much everyone who saw the tank during this period thought otherwise...😫

Eventually, the familiar "patina" of harder algae came to prominence.  And minor biofilm on the softer parts of the wood will still pop up on occasion...Just like it does in nature. It's normal. It's not dangerous.

It's okay.

And of course, along the way, you can incorporate some "biological helpers", like algal and detritivorous-consuming fishes and even snails (yikes!) to help out. Of course, many, many fishes will "peck" at biofilms and other growth on wood and botanicals as a part of their daily "foraging" activities.

And of course, good old-fashioned aquarium husbandry and stepped-up maintenance practices never hurt, either!

 

And having a good, soft-bristled toothbrush on hand can help with the "day-to-day" upkeep, if needed. Likely, the stuff will continue to return until the "fuel" which caused their appearance and growth in the first place diminishes.

Obviously, happy endings typically will happen with aquarium wood, given the passage of time and perhaps a bit of assistance from the fish geek, but it's important to understand WHY the algae and biofilms appear on wood, and how to react when they happen.

Like so many things in a truly "natural" aquarium, they may not meet our aesthetic standards, but if we have a greater understanding of just what they are, why they appear, and how to address them (or not..), we can make that "mental shift" that you hear me ranting about so often on these pages.

Embracing a new paradigm of what a "natural" aquarium really is.

One that doesn't cause us to rush off, headless, screaming into the night (or onto Facebook) when some algae or biofilm appears! Goes with the territory. Embracing Nature in all of her glory is what we're all about. 

Expectations. Education. Patience.

All "core skills" which we as aquarists need to acquire to bolster our success, understanding and perseverance as we push the boundaries of aquarium keeping.

And of course, I'm fascinated by the world of biofilms, decomposition, microorganism growth and detritus, and their potential for serving as supplemental food sources for our fishes.

And this stuff plays right into that! 

Some fishes are thought to consume wood. Others are deriving sustenance from materials which form on wood...

Loricariids are the textbook example of this...

Now, the idea of xylophagy (the consumption and digestion of wood) is of course, a pretty cool and interesting adaptation to the environment from which these fishes come from. And as you'd suspect, the way that wood is consumed and digested is equally cool and fascinating! 

It's thought that the scraping teeth and highly angled jaws of the Loricariidae are a perfect adaptation to this feeding habit of scraping wood. And of course, it's even argued among scientists that these fishes may or may not actually digest the wood they consume! While scientists have identified a symbiotic bacteria which is found in the gut of these fishes that helps break down wood components, it's been argued by some the the fishes don't actually digest and metabolize the wood; indeed deriving very little energy from the wood they consume!

In fact, a lab study by Donovan P. German was described in the November, 2009 Journal of Comparative Physiology, in which several species were fed wood and found to actually digest it quite poorly: 

"...in laboratory feeding trials, (P. cf. nigrolineatus and Hypostomus pyrineusi)  lost weight when consuming wood, and passed stained wood through their digestive tracts in less than 4 hours. Furthermore, no selective retention of small particles was observed in either species in any region of the gut. Collectively, these results corroborate digestive enzyme activity profiles and gastrointestinal fermentation levels in the fishes’ GI tracts, suggesting that the wood-eating catfishes are not true xylivores such as beavers and termites, but rather, are detritivores like so many other fishes from the family Loricariidae."

Did you see that? Detritioves.

Hmm...

And this little nugget from the same study:  "...The fishes consumed 2–5% of their body mass (on a wet weight basis) in wood per day, but were not thriving on it, as P. nigrolineatus lost 1.8 ± 0.15% of their body mass over the course of the experiment, and Pt. disjunctivus lost 8.4 ± 0.81% of their body mass."

Yet, anatomical studies of these fishes showed that the "wood-eating catfishes" had what physiologists refer to as "body size-corrected intestinal lengths" that were 35% shorter than the detritivore species. What does this mean? Could they have perhaps had at one time- and subsequently lost- their ability to digest wood?

Maybe?

Arrgh!

To the point of the argument that they are primarily detritivores, consuming a matrix of biofilm, algal growth, microorganisms, and (for want of a better word) "dirt"- what does this mean? In fact, many species in the Loricariidae are known to be detritivores, and this has made them remarkably adaptable fishes in the aquarium.

Now, my limited personal experience with Loricariidae is undoubtedly nothing like many of yours, and an observation I made not too long ago is at best anecdotal- but interesting:

If you follow "The Tint", you know I've had an almost two year love affair with my Peckolotia compta aka "L134 Leopard Frog"- a beautiful little fish that is filled with charms. Well, my specimen seemed to have vanished into the ether following a re-configuration/rescape of my home blackwater/botnanical-style aquarium. I thought somehow I either lost the fish during the escape, or it died and subsequently decayed without my detecting it... 

For almost three months, the fish was M.I.A., just....gone.

And then one, day- there she was, poking out from the "Spider Wood" thicket that forms the basis of my hardscape! To say I was overjoyed was a bit of an understatement, of course! And after her re-appearance, she was been out every day. She looked just as fat and happy as when I last saw her in the other 'scape...which begs the question (besides my curiosity about how she evaded detection): 

What the @#$% was she feeding on during this time?

Well, I suppose it's possible that some bits of frozen food (I feed frozen almost exclusively) got away from my population of hungry characins and fell to the bottom...However, I'm pretty fastidious- and the other fishes (characins) were voracious! I think it was more likely the biofilm, fungal growth, and perhaps some of the surface tissues of the "Spider Wood" I used in the hardscape that she was feeding on.

This stuff does recruit some biological growth on it's surfaces, and curiously, in this tank, I noticed during the first few months that the wood seemed to never accumulate as much of this stuff as I had seen it do in past tanks which incorporated it.

So yeah, the point of this tortured example is that I think we should all think of wood in our aquariums as more than just an "aesthetic prop." Rather, it should be viewed as an element of a naturally-functioning closed aquarium habitat. An important "producer" or "aggregator" of supplemental foods, and as a source of important tannins, humic substances, and other compounds for environmental enhancement.

That's the coolest part of the "wood equation", if you ask me!

Stay creative. Stay curious. Stay resourceful. Stay engaged...

And Stay Wet.

 

Scott Fellman

Tannin Aquatics 

 

 

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