Aquascaping as an art and science is really starting to evolve.
We're seeing an interesting evolution of styles, ideas, and inspiration coming on line. And a very rapidly growing interest in utilizing botnaicals in all sorts of aquaecapes is bringing new questions.
Like, the one I receive quite a bit:
"Which of your botanicals last the longest, Scott?"
And of course, there most certainly ARE a bunch of botanicals which hold up better during long periods of submersion, there are many variables which can affect their durability, such as the water chemistry, current, the types of fishes you maintain, etc.
Hell, just being submerged in water over time softens stuff...
Water is a tremendous "solvent"- right?
I mean, do the words "Grand Canyon" mean anything to you?
Oh, back to botanicals...
There are some variables which apply:
One "instant variable" is the constant "grazing" or foraging activities of some species of fishes and shrimp (and snails!), which hasten or begin to break down the tissues of even the most durable pods over time, often from the inside out- a factor that we don't always think about.
And of course, our recommendations to prepare your botanicals by boiling or soaking begin the process by "softening up" these materials- to what extent is largely dependent upon which botanicals we're talking about- but all soften to some degree via the preparation process. Lignins and cellulose do soften up a little bit when boiled.
Let's think about the actual physical structure of these materials for a moment.
Most of the more durable botanicals we work with are the seed pods of various species of plants, and often are comprised of a wall-like structure called a pericarp. The pericarp has a durable single-cell layer called the exocarp, which facilitates gaseous exchange and protects the seed or fruit within. This layer can be pretty solid, and depending upon the species, may last a pretty long time under water.
That being said, all botanical materials will soften over time, gradually breaking down, often from the inside, where the tissues are softer and less durable. Fishes like Plecos, some characins, and many species of snails and shrimp will gradually consume portions of both the exterior and interior parts of the pod, which may also break down from fungal or bacterial action over time.
You've sent us lots of pics over the years of fishes and shrimp consuming the softer interior parts of many botanicals- a process which happens in Nature, too!
Some materials, like Dysoxylum and Caliotropis pods, tend to soften rather quickly- at least, their interiors do- and can often breakdown very rapidly. They are very attractive to shrimp! In fact, we don't recommend either one of them for use in an aquarium that doesn't contain shrimp, because their soft interiors are more likely to foul before they will really break down.
So, with all of these factors in play, there are, of course, some botanicals which will really stand up well to long term submersion, and we'll look at just a few of our most durable faves here.
Let's face it, I realize that whenever I compile a list of ANYTHING about the stuff we sell, it's kind of tough not to accuse me of some form of "crass commercialism..." I mean, it's sort of like a promotion for our stuff, right?
That being said, it's important for many of you to know the durability of the materials you're spending your hard-earned cash on, so please make that your takeaway here.
This is by no means an exhaustive examination, or even THE definitive ranking for them- but the few that made my personal "short list" of "Most Durable" are certainly ones that have proven to be long-term "players" in both my systems and those of others in our community for some time!
You will no doubt have your own additions and/or observations on this stuff- so let's hear 'em!
Here are my faves for durability and longevity:
1) Monkey Pot- this is actually a seed pod from plantation-grown Brazil nut trees (Lecythis pisonis), so you'd expect it to be extremely durable...and it is! These pods are without a doubt, the longest-lasting botanicals we work with. I've had specimens go two years or more without any significant "softening" occurring. Oh, and they are a great place to hide, and they release some water-tinting tannins, so all-in-all they're a real great "vehicle" for natural-style aquariums.
2) Mokha Pods- these are really durable, almost "nut-like" pods, from the Shrebera swieteniodes tree, and will hold their shape and "structural integrity" for extended periods of time. These pods are a really great aesthetic component for your 'scape, offering that "generic tropical" look that will no doubt work in all sorts of aquascapes! Of course, for a Southeast Asian or Indian-Inspired biotope aquarium or vivarium, these would be truly great to use.
3) Cariniana Pods - This is the prototype awesome tropical seed pod for aquarium use! I still have a CarinianaPod in use that's been submerged, more or less continuously, for the better part of 3 years. That pretty much says it all. Now, what we call a "pod" is really what a botanist would call a "dehiscent pyxidia"- a really cool way of saying that it's a fruit capsule, from which the upper part falls off when the seeds are released! Fishes like Apistos will take to them easily, utilizing their cavity as a place to rear and protect their clutches of fry, much as they would exploit such a submerged seed pod in nature. Now, if only my supplier in Brazil could ship to us again soon!
4) Sterculia Pods- Of course, you'd expect these large, woody pods to be durable! And- surprise- they are! Although they will soften quicker than most of the larger pods mentioned here, they are among the most durable and versatile botanicals we offer. It's actually the fruit, or "follicle" (as botanists call it) of the jungle tree Sterculia foetida. Calling it a "pod" is a little stretch, actually- but not much! (Unless you're a botanist, in which case your colleagues would just totally hate on you...) It's also known locally in Southeast Asia as the "Java Olive."
What we can confidently say is that these botanicals, like pretty much every seed pod or leaf we place in the aquarium, will leach some amount of tannins, lignin, and other organics into the water over time. You certainly wouldn't use Sterculia Pods for the sole purpose of providing "tint" to your water, but you would be perfectly correct using them for aesthetics and utility as a shelter. At the end of the day, the Sterculia Pod is truly one of the most useful, attractive, and versatile botanicals you can add to your aquarium. Not a day goes by that we don't find ourselves thinking of some new application for them in an aquarium, terrarium, or vivarium!
5) Afzelia Pod- Okay, I'm sort of cheating, because even though you can and should use these guys in aquariums, they look amazing in vivariums! The seed pod of Afzelia xylocarpa from Southeast Asia, is a big, heavy, and undeniably attractive botanical that will serve a variety of uses, ranging from simple hardscape piece, to serving as a perch, feeding area, or shelter for your frogs. These big, solid pods last a good long time under water. Like, potentially years.They are excellent for vivariums, because they stand up to humidity really well.
In the end, I suppose that you could conclude that the word "durability" is a relative term in the context of submerged botanicals.
What I see as "long-lasting" might be unacceptably short to some- especially newcomers to our game who are accustomed to more "traditional" hardscape materials, like wood, which typically lasts a really long time under water. Like, decades...
That being said, I think it's at least important to share some sort of "baseline" observations of this "durability factor", so that you can have a "starting point" for creating the kind of hardscape that you're trying to achieve!
So, while I can't guarantee that any botanical will last "x" amount of time underwater, I am more than hoary to give you my opinion on the more durable ones, based on my personal experiences. By knowing what will last longest, you can make more informed decisions- and we're always happy to help you with that!
Of course, the tradeoff with "durability" in botanicals is their ability to recruit biofilms, fungal and algal turfs on their hard surfaces. This is, of course, not a bad thing. However, for those of you out there who love pristine, spotless hardscape items, you'll be breaking out the stiff-bristled brush frequently, or replacing them after a few months with new specimens.
Again, part of the "function" of botanicals- and wood- for that matter- in addition to their utility as hiding spaces, etc., or their ability to influence water chemistry, is to serve as a substrate for growth of these important supplemental food sources for many aquatic organisms, just like they do in Nature.
We have to get used to this stuff.
Understanding that what the uninitiated to our obsession see as "gross" or "dirty" as beautifully "natural" and "functional" is a true mental shift- one of many we ask you to make when working with a natural, botanical-style aquarium.
And, if you can keep these materials in play for extended periods of time- it's just that much more satisfying, isn't it?
Kepe experimenting, observing, and enjoying!
Stay creative. Stay excited. Stay engaged. Stay curious...
And Stay Wet.