Greener pastures?

In the 8 years since Tannin made its debut, we've seen a lot of incredible growth in the interest of creating truly more natural aquatic setups. Over these years, it's been really satisfying to see aquarists studying and appreciating some of the more dynamic habitats in Nature, and attempting to replicate them in our aquariums.

Land and water...

If there's one foundational concept to the botanical method "philosophy",  it's that land and water are inexorably linked together. And, I think that when we contemplate the dynamic of how water and the aquatic environment interact, it makes us look at aquatic habitats- and our aquariums-a bit differently.

Seasonally-inundated forest floors and grasslands, such as the Igapo and Varzea in South America, are some of the most fascinating and dynamic ecologies in Nature- and they're ripe for replicating-in both form and function- in our aquariums. 

The idea of the "Urban Igapo"- our home-grown version of these habitats, has been something we've talked about for about 4 years or so now, and I've seen more and more hobbyists attempting to replicate them in aquariums. And of course, in addition to questions about the techniques and processes involved to create such a display, many of you want to know what the best plants are to utilize in your own systems.

The concept behind the "Urban Igapo" is pretty straightforward:

The idea is to replicate to a certain extent, the seasonal inundation of the forests and grasslands of of Amazonia by starting the tank in a 'terrestrial phase", then slowly inundating it with water over a period of weeks or more; then, running the system in an "aquatic phase" for the duration of the 'wet season", then repeating the process again and again.  


Because you can do this in the comfort of your own home, we called the concept the "Urban Igapo." A few years years ago, we went more in depth with some of the procedures and techniques that you'd want to incorporate into your own executions of the idea.


And, as  there are with so many things in the modern aquarium hobby, there is occasionally some confusion and even misunderstandings about why the hell we do this in the first place! 

Well, that's a good question!

I mean, the whole idea of this particular approach is to replicate as faithfully (and practically) as possible the seasonal wet/dry cycles which occur in these habitats. It starts with a dry or terrestrial environment, managed as such for an extended period of time, which is gradually flooded to simulate inundation which occurs when the rainy season commences and swollen rivers and streams overflow into the forest or grassland.

Sure, you can replicate the "wet season" only- absolutely. I've seen tons of tanks created by hobbyists to do this. However, if you want to replicate the seasonal cycle- the real magic of this approach- you'll find as I did that it's more fun to do the "dry season!"

Think of it in the context of what the actual aquatic environment is- a forest floor or grassland which has been flooded. If you develop the "hardscape" (gulp) for your tank with that it mind, it starts making more sense. And, what do you find on a forest floor or grassland habitat? Soil, leaf litter, twigs, seed pods, branches, grasses, and plants.

 Just add water, right?

Well, sort of.

Of course, when you proffer ideas like this, in the modern aquarium hobby, the heat will follow!

I recall, a few years back, one of my friends who was presenting his experiences with this approach was just getting pounded on a forum by some, well- let's nicely call them "skeptics" (aka "assholes")- you know, the typical internet-brave "armchair expert" types- about why you'd do this, and how it can't possibly lead to a stable aquarium- and how it's "not a blackwater aquarium" (okay, it wasn't presented as such, but it could be...) and that it's just a "dry start" aquarium (Well, sort of, but you have to understand the concept behind it, dude!), and that "you don't need to do it this way" and...well- that kind of stuff.

I mean, the full compliment of negative, ignorant comments and attacks by some people clearly frightened about someone trying to do something a little differently was on display. In a typical display of online-warrior hypocrisy, one particularly nasty hack did not even bother to research the idea or think about what it was really trying to do before laying into my friend.

Apparently, for these people, there was a lot to unpack. The "gotcha!" kinds of attacks, asserting that this is something that is already done by the whole aquarium world are particularly ignorant and offensive to any thinking aquarist.

I mean, first of all, the idea is not intended to be a "dry start" planted tank. It just isn't. I mean, yeah-it starts out "dry", but that's where the similarity ends. This ignorant comment is a classic example of the way some hobbyists make assumptions based on a superficial comprehension of something.

We aren't simply trying to grow aquatic plants here. It's about creating a habitat of terrestrial or riparian plants snd grasses, allowing them to establish, snd then inundating the display. Most of the terrestrial grasses will simply not survive extended periods of time submerged. Now, you COULD add adaptable aquatic plants- there are no "rules"- but the intention is to replicate a seasonal dynamic.


The other point, which is utterly lost on some people, is that establishing a "transitional" environment in an aquarium takes time and patience. It's not a 48 hour "project." One particularly nasty dummy literally called the process "complete nonsense" and a "waste of time." This is exactly the kind of self-righteous, ignorant hobbyist who will never get it. In fact, I'm surprised guys like that actually have any success at anything in the hobby!

Oaky, well, enough of my venting...But you can understand how such B.S. really doesn't play well around here!

So, a lot of you want to know what plants to use, and if they can tolerate the transition from terrestrial to aquatic environments well.

Some do, some don't. (How's that for concise info!). I've played with grasses which are "immersion tolerant", such as Paspalum. This stuff will "hang around" for a while while submerged( for about a month and a half to two months, in my experience) before ultimately succumbing. Sometimes it comes back when the "dry season" returns. However, when it doesn't survive, it decomposes in the now aquatic substrate, and adds to the biological diversity by cultivating fungi and bacteria.

You can use many plants which are riparian in nature or capable of growing emmersed, such as my fave, Acorus, as well as all sorts of plants, even aquatics, like Hydrocotyle, Cryptocoryne, and others. These can, of course, survive the transition between aquatic and "terrestrial" environments.


If you want to mimic one of these habitats in the most realistic manner possible, follow the exact wet and dry seasons as you'd encounter in the locale you're inspired by. Alternatively, I'd at least go 2 months "dry" to encourage a nice growth of grasses and plants prior to inundation.

Of course, if I had to select only one plant for inclusion in the "Urban Igapo", it would have to be Acorus. Hardy, attractive, versatile, and essentially "bulletproof", Acorus is perfect for this type of setup.

Although it's far more common as a plant found around the water's edge in ponds, Acorus can do quite well partially submerged indefinitely, or even fully submerged for extended periods of time. It will glow very slowly underwater, but it will survive just fine. Although it's a native of Eastern Asia, it's ideal for simulations of the Igapo habitat.

Acorus can handle all sorts of light, from diffuse, partially shaded sunlight, to natural room ambient light, or even LED's. Its remarkable adaptability is only one of its many selling points.

And of course, there are true aquatic plants which are found in these seasonally-inundated habitats...

There are literally dozens of species of true aquatic plants that are found in these inundated grasslands and forests, and a number of representative species or genera are commonly kept in aquariums. Most of the aquatic plant life occurs in Varzea and Igapo floodplains, both of which we've talked about before. The Varzeaare seasonally-flooded forest areas, which are inundated by pH-neutral "whitewater", and can reach significant depths, whereas the Igapo are generally shallow, blackwater environments with relatively low nutrient content and acidic soils. 

Varzea forests are extremely rich, which leads to a very rich aquatic ecosystem when inundated, and tend to have greater density of aquatic plants. Várzea forest soils have high nutrient contents because they receive high loads of sediment (from the Andean and pre-Andean regions) from the whitewater rivers nearby.

Igapó forests, on the other hand do not receive this seasonal influx of sediments , which is why they have relatively inorganic nutrient- poor soils. Igapo waters are acidic, with a pH ranging between 4 and 5, and are rich in organic materials- particularly humic and fulvic acids. It is also thought by scientists that the seasonal inundation of the Igapo soils creates anoxic conditions, limiting plant growth in general.

So, we have two contrasting aquatic environments, with widely varying conditions available for the growth of plants. Obviously, the Varzea forests are better conditions for a wider variety of plants, with their less acidic water and higher overall nutrient availability than Igapo, which tend to be representative of a more "classic" blackwater habitat, with far less plant growth and fewer species of fishes.

The other important factor affecting plant growth in these aquatic habitats is light; or specifically, light penetration. This affects diversity of both the terrestrial grasses and aquatic plants present in the waters. In the blackwater Igapo areas, light only penetrates down to depths of  1-2 meters, and many submerged grasses and terrestrial forest plants simply die back from lack of light. And the forest canopy adds to the shading in some areas, further reducing the amounts of light available to plants.

It should hardly be surprising that the diversity of plants, both terrestrial and aquatic, which survive in the inundated season is much greater in the areas of the savannas flooded by clear, nutrient-rich waters. In fact, it was determined in one study that around 900 species of grasses alone occur in the Pantanal (Varzea ) region, with almost 250 of them considered aquatic!

(The flooded Pantanal region. Image by Alicia Yo at the English Language Wikipedia)

Okay, terrestrial grasses are interesting, but they're not something that we typically will be keeping in our aquariums, right? However, the common "Barnyard Grass", Echinochloa, is ubiquitous worldwide and would make a and interesting subject to play know, planting some in rich soils and filling it with water...oh, man, that's the kind of experiment I'm into!

Who's on THIS idea?

(Echinochloa- Image by Michael Becker, used under CC BY-SA 3.0)

So, what types of aquatic plants would you expect to find in these habitats? Well, in the here are a few:

Nymphaea, Polygonum, Salviania, and Pistia, and the much-loved Water Hyacinth, Eichhornia crassipes, and yeah, some species of "Amazon Sword Plants", just to name a few.

I've kept Polygonum species before (ironically, in more of a "blackwater" setting) and had great success with them, so a more "clearwater" botanical-style aquarium would no doubt really help them grow like mad!


Floating plants seem to be some of the dominant aquatic species found in both regions, with no shortage of well-known, readily varieties from which to choose. Now, their suitability for aquarium use (as opposed to ponds) is debatable, but there are numerous varieties of  Water Hyacinth (Eichhornia) to play with if you're so inclined!

In the Igapo areas, the predominant aquatic plants seem to be Cabomba, Nymphaea, and Utricularia, all of which are commonly kept in aquaria or ponds.

(Nymphaea, image by TC Tao, used under CC BY-SA 3.0)




I have always had a soft spot for Cabomba, being one of the first aquatic plants I've ever kept. So, seeing that it's at home in a blackwater habitat is, well- comforting, lol! It's super adaptable, fast-growing, and easily obtainable...Winner!

 So, yeah- an article on plants from a guy who is hardly a plant person! 

Yeah, I'm being totally honest here: I don't really know that much about aquatic plants. Sure, I can tell an Anubias barteri from an A. coffeefolia, or Water Sprite from Anacharis...I can even sort of ID a few Cryptocorynespecies...

But that's really it.

Java Moss? Sure. All of those other fancy mosses? Um, no.

I mean, they're all moss, right?

(all moss enthusiasts are cringing now!)

And I'm okay with that.

And I have a sort of theory that, while a lot of plants aren't found in blackwater habitats, many, many species are adaptable to this environment in the aquarium, especially if their lighting and nutrition requirements are met.

Now, if you're trying to replicate a specific environment, or create a highly accurate biotope aquarium, such "freelancing" is to be discouraged, I know. However, for most of us who are simply content with creating a great display, it's "game on!"

Many of us are at least semi-obsessed with replicating, to a certain extent, the flooded forest (iagpo) habitats of Brazil, which, as outlined above, contain, but are not generally known for a huge variety of true aquatic plants, there is another "frontier" to play with:

Terrestrial plants and grasses that can tolerate immersion for extended periods of time. 

This is, as far as I know, and entirely new and different "playground" for aquarists, as we've typically concentrated on the true aquatic plants in our tanks. With a greater interest in these habitats, and the evolving techniques of the planted aquarium work- specifically the use and continued development of soils, the possibilities are expanding.

Let's do a little more collective research on this topic, and make a few exciting discoveries...because that's what we do, right?

Have at it!

Stay resourceful. Stay observant. Stay diligent. Stay persistent...

And Stay Wet.


Scott Fellman

Tannin Aquatics

Scott Fellman
Scott Fellman


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