Just add leaves...

(Dedicated to Takashi Amano (July 8, 1954 – August 4, 2015)

When you consider the types of aquariums that we work with, I would imagine that it is probably funny to outsiders, or those new to our obsession, to hear us going on and on about utilizing dried leaves, twigs, and seed pods in our aquariums with words such as "methodology" and "technique" and the like.

I can't help but think that the great Takashi Amano, who spent years studying many aspects of Nature and her influence on the aquatic environments, would really love this stuff. I think that he'd love the unique aesthetics, sure- but I think he'd especially love how these ephemeral materials we play with can influence the way our aquariums function. It's the essence of his embrace of the Japanese philosophy of wabi-sabi. I think he'd gently scold the hobby and perhaps lament how it has embraced mostly the more superficial aspects of Nature, beautiful as they are- as opposed to "the whole picture."

I suppose that there are occasional smirks and giggles from some corners of the hobby when they initially see our tanks, with some thinking, "Really? They toss in a few leaves and they think that the resulting sloppiness is "natural", or some evolved aquascaping technique or something?"

Funny thing is that, in reality, it IS a sort of evolution, isn't it?

I mean, sure, on the surface, this doesn't seem like much: "Toss botanical materials in aquariums. See what happens." It's not like no one ever did this before. And to make it seem more complicated than it is- to develop or quantify "technique" for it (a true act of human nature, I suppose) is probably a bit humorous. 

On the other hand, it's not just to create a cool-looking tank. We don't embrace the aesthetic of dark water,  a bottom covered in decomposing leaves, and the appearance of biofilms and algae on driftwood because it allows us to be more "relaxed" in the care of our tanks, or because we think we're so much smarter than the underwater-diorama-loving, hype-mongering competition aquascaping crowd.

Well, maybe we are? 😆

I mean, we are doing this for a reason: To create more authentic-looking, natural-functioning aquatic displays for our fishes. To understand and acknowledge  that our fishes and their very existence is influenced by the habitats in which they have evolved. 

Wild tropical aquatic habitats are influenced greatly by the surrounding geography and flora of their region, which in turn, have considerable influence upon the population of fishes which inhabit them, and their life cycle. The simple fact of the matter is, when we add botanical materials to an aquarium and accept what occurs as a result-regardless of wether our intent is just to create a different aesthetic, or perhaps something more- we are to a very real extent replicating  the processes and influences that occur in wild aquatic habitats in nature.

The presence of botanical materials such as leaves in these aquatic habitats is fundamental.


In the tropical species of trees, the leaf drop is important to the surrounding environment. The nutrients are typically bound up in the leaves, so a regular release of leaves by the trees helps replenish the minerals and nutrients which are typically depleted from eons of leaching into the surrounding forests.

And the rapid nutrient depletion, by the way, is why it's not healthy to burn tropical forests- the release of nutrients as a result of fire is so rapid, that the habitat cannot process it, and in essence, the nutrients are lost forever.

Now, interestingly enough, most tropical forest trees are classified as "evergreens", and don't have a specific seasonal leaf drop like the "deciduous" trees than many of us are more familiar with do...Rather, they replace their leaves gradually throughout the year as the leaves age and subsequently fall off the trees.

The implication here?

There is a more-or-less continuous "supply" of leaves falling off into the jungles and waterways in these habitats, which is why you'll see leaves at varying stages of decomposition in tropical streams. It's also why leaf litter banks may be almost "permanent" structures within some of these bodies of water!

And, for the fishes and other organisms which live in, around, and above the litter beds, there is a lot of potential food, which does vary somewhat between the "wet" and "dry" seasons and their accompanying water levels. The fishes tend to utilize the abundant mud, detritus, and epiphytic materials which accumulate in the leaf litter as food. During the dry seasons, when water levels are lower, this organic layer compensates for the shortage in other food resources. 

During the higher water periods, there is a much greater amount of allochthonous input (remember that?) from the surrounding terrestrial environment in the form of insects, fruits, and other plant material. I suppose that, in our aquariums, it's pretty much always the "wet season", right? We tend to top off and replace decomposing leaves and botanical more-or-less continuously.

Now, of course, where is where I get into what I will call "speculative environmental biology!"

What if we stopped replacing leaves and even lowered water levels or decreased water exchanges in our tanks to correspond to, for example, the Amazonian "dry season" (June to December)...And if you consider that many fishes tend to spawn in the "dry" season, concentrating in the shallow waters, could this have implications for breeding?

Could this be a re-thinking or re-imagining of how we spawn and rear our fishes?

I believe so.

I further proffer that we need to look a lot deeper into the idea of environmental manipulation for the purpose of getting our fishes to be healthier, more colorful, and especially, to spawn. Now I know, the idea is nothing new on a "macro" level- we've been increasing and lowering water temps in our aquariums, adjusting lighting levels, and tweaking environmental parameters to get fishes to spawn for a long time.

(Awesome pic by Mike PA Calnun)

Killie keepers have played with this concept in the drying and incubation periods in annual killifish eggs. That's some serious "next-level stuff" that's been done for a long time! Specific environmental manipulations for definitive results (ie; controlled egg hatching, etc.)

However, I don't think we've been doing a lot of real specific environmental manipulations...like adjusting water levels, increasing nutrient loads (ie; "pulsing" adding leaves and other botanicals), fostering biofilm growth, manipulating current, dissolved oxygen, food types, etc. for the expressed purpose of general husbandry and yeah- the spawning many other types of fishes.

I think that there are so many different things that we can play with- and so many nuances that we can investigate and manipulate in our aquariums to influence fish health and spawning behavior. I think that this could even add a new nuance to a typical biotope aquarium, such as creating an aquarium which simulates the "Preto da Eva River in Brazil in October", or whatever...with appropriate environmental conditions, such as water level, amounts of allochthonous material, etc.

Not just an aesthetic representation designed to mimic the look of the habitat- but a "functionally aesthetic" representation of a natural habitat, intended to operate like one..Full time.

Nuances. Micro-influences. Subtle steps. 

The possibilities are endless here! How do we start?

Well, we make those "mental shifts" and accept the dark water, the accumulation of leaves and botanicals, the apparent "randomness" of their presence. We study the natural habitats from which they come, not just for the way they look- but for WHY they look that way, and for how the impacts of the surrounding environments influence them in multiple ways.

There is a tremendous amount of academic material out there for those willing to "deep dive" into this. And a tremendous amount to unravel and apply to our aquarium practices! We're literally just scratching the surface. We're making the shifts to accept the true randomness of Nature as it is.  We are establishing and nurturing the art of "functional aesthetics."

My real hope for the future? 

That one day, when some kid somewhere adds some Latifolia pods, Selatan Catappa bark, or Banana stem pieces to her wild Betta tank, for example, and someone asks why, they'll respond with something like, "Because these materials mimic the allochthonous inputs which occur in their wild habitats, and provide foraging and humic substances which will manipulate the aquarium environment and encourage the development of biofilms and other microorganisms for their long-term health" 

That's a mouthful.

Okay, I doubt some 11-year-old will respond exactly in those words- but I think that she'd suggest that the idea of using botanicals to do more than just create a pretty look in the aquarium is important. My hope is that this mindset will percolate into the consciousness of the general hobby, for the good of all who play with tropical fishes. Not just for us obsessed weirdos!

Perhaps one day, among the things we indoctrinate neophyte aquarists to play with as fundamental skills, besides water exchanges, quarantine, and careful stocking, will be things like "adding appropriate botanical materials to the aquarium to facilitate more natural conditions for the aquatic organisms we keep."

This is, indeed what we mean when we talk about how we operate at "The delta at the intersection of science and art."

You're there- because you're HERE.

This is the mission of Tannin Aquatics.

Study the natural. Embrace the ephemeral. Think of the possibilities. It starts with observing and studying nature. And your aquarium.

Then, just add leaves...And open your mind...

Amano himself, I think, would appreciate this.

Stay studious. Stay curious. Stay creative. Stay diligent. Stay consistent...

And Stay Wet.


Scott Fellman

Tannin Aquatics

Scott Fellman
Scott Fellman


2 Responses

Scott Fellman
Scott Fellman

August 18, 2020

Hi Allen,

Thanks for the kind words. Here’s a link to a couple of relevant pieces on leaves and their addition to the aquarium:



Hope these help!


Allan Miller Petersen
Allan Miller Petersen

August 15, 2020

Thanks for sine great articals, i Found this, because Ive searched for fore what to know when adding leaves to an already established tank, U have commented it sevarel times, that I should be careful b4 just adding leaves, i know u have already made at artical that explains how, i just can’t find it. So if u world please link it fore me, it world be amazing.
Im a fairly new aqua neerd. Have a 6 month Old South American tank with red nose, sterbais and a few keyhole chiclids, ive used a couple of catapa leaves from the Beginning, Adding new every month, but now a Want to ad some leave litter, And i need to know how much i can ADD , and so one.. thanks a lot,

Leave a comment