A tale of...Tucanos...

Some of the biggest ideas start with the smallest executions.

That's a good philosophy and attitude, IMHO. And more economical, too! 

We've talked many times about the idea of using so-called "nano aquariums" as a sort of "testbed" for ideas and concepts. The idea that it's easier to try some of these exotic experiments on a small scale than it is to go right to the "big time" is top of mind.

Not long ago, you followed us on such a journey with a simple, but well-thought-out Ultum Nature Systems 45A all-in-one aquarium, set up for a very specific little fish.

It was a great example of this "big idea/small execution" philosophy.

I had been "mentally testing" my concept of what came to be called the "Tucano Tangle"- a biotope inspired aquarium to replicate aspects of the habitat of the Tucanoichthys tucano, a small characin found only in one area, the Rio Uaupes- specifically, "...a brook emptying into the igarape Yavuari"...like, that's pretty damn specific, right?

Damn, those little bodies of water  in the jungle again...

It was time to really get past just the hobby literature for this one- and that meant a voyage into more scholarly writings. I was doing a geeky "deep dive" into this type of habitat in Amazonia, and stumbled upon this gem from a scientific paper by J. Gery and U. Romer in 1997:

"The brook, 80-200cm wide, 50-100 cm deep near the end of the dry season (the level was still dropping at the rate of 20cm a day), runs rather swiftly in a dense forest, with Ficus trees and Leopoldina palms...in the water as dominant plants. Dead wood. mostly prickly trunks of palms, are lying in the water, usually covered with Ficus leaves, which also cover the bottom with a layer 50-100cm thick. No submerse plants. Only the branches and roots of emerge plants provide shelter for aquatic organisms.

The following data were gathered by the Junior author Feb 21, 1994 at 11:00AM: Clear with blackwater influence, extremely acid. Current 0.5-1 mv/sec. Temp.: Air 29C, water 24C at more than 50cm depth... The fish fauna seems quite poor in species. Only 6 species were collected I the brook, including Tucanoichthys tucano: Two cichlids, Nannacara adoketa, and Crenicichla sp., one catfish, a doradid Amblydoras sp.; and an as yet unidentified Rivulus, abundant; the only other characoid, probably syncopic, was Poecilocharax weitzmani."

Yeah, it turned out to be the ichthyological description of the little "Tucano Tetra", and was a literal treasure trove of data on both the fish and its habitat. I was taken by the decidedly "aquarium reproducible" characteristics of the habitat, both in terms of its physical size and its structure. 

Boom! I was hooked.

Now, I admit, I wasn't interested in, or able to safely lower the pH down to 4.3 (which was one of the readings taken at the locale), and hold it there, but I could get the "low sixes" nailed easily! Sure, one could  logically call me a sort of hypocrite, because I'm immediately conceding that I won't do 4.3, and I suppose that could be warranted...

However, there is a far cry between creating 6.2pH for my tank, which is easy to obtain and maintain for me, and "force-fitting" fishes to adapt to our 8.4pH Los Angeles tap water! 

And of course, with me essentially trashing the idea of executing a hardcore 100% replication of such a specific locale, the idea was essentially to mimic the appearance and function of such an igarape habitat, replete with lots of roots and leaf litter.

And the idea of executing it in a nano-sized aquarium made the entire project more immediately attainable and a bit less daunting. I wanted to see if I could pull off a compelling biotope-inspired setup on a small scale.

That's where my real interest was.

So, even the "create the proper conditions for the fish instead of forcing them to adapt to what's easiest for us" philosophy can be nuanced! And it should! I don't want to mess with strong acids at this time. It's doable...a number of hobbyists have successfully.  However, for the purposes of my experiment, I decided to happily abstain for now, lol.

And without flogging a dead horse, as the horrible expression goes, I think I nailed many of the physical attributes of the habitat of this fish. By utilizing natural materials, such as roots, which are representative of those found in the fish's habitat, as well as the use of Ficus and other small leaves as the "litter" in the tank, I think we created a cool biotope-inspired display for these little guys!

And man, I love this tank.

Being able to pull off many aspects of the look, feel and function of the natural habitat of the fish was a really rewarding experience.

That's one example of this philosophy in action. Again, it's NOT perfect. It's certainly something that can- and should- be improved upon. The pH thing, for example. But the physical environment; the biological nuances...the long-term function of this type of aquarium microcosm...I think we are well on our way to building a lot of "best practice" stuff here. 

I'm still not satisfied yet...

However, I think it's a good start.


I think it also requires the usual caveats- a "mindset shift" that embraces the fact that the natural habitats we love don't always meet our "acculturated" aesthetic expectations. We need to understand that Nature does her own thing, regardless of whether we "approve" of it or not! 

Like, I love it more than any other "biotope-inspired" tank I've ever set up.  

And, people have asked why I didn't do it in a larger tank. Well, it's pretty simple: I tried it on a small scale because of the tiny size (and breath-taking price!) of the Tucanos; I figured they'd be utterly lost in a larger (like 50 US gallons) aquarium. Not to mention, that I'd have to take out a second mortgage on my home to acquire a population significant enough to make it look like there were any fish in the tank! 

So, here I am. 

Of course, I love the physical appearance of the aquarium so much that I totally want to scale this baby up! That's a total fist-geek mindset, for sure. Now, the idea of populating a significantly larger tank entirely with the little Tucanos- although tempting from a conceptual standpoint, is really an economically impractical approach. I suppose I could do that...but at $12USD each, to get a school justifiably large enough to place in a 50-gallon tank would be pretty damn pricy!

Would I add some other fishes to this tank?

My original plan was to sort of stay reasonably monospecific, with just the Tucanos. However, reaserch showed that some fishes are found sympatrically with the Tucanos- specifically, the cute little cichlid, Ivanacara adoketa, some Amblydoras catfishes, Rivulus (yeah, killies- but the f- ing things jump like mad...and in my open-top tank...), and the coolest of all- the equally tiny and somewhat pricy Poecilocharax weitzmani- a fish that looks a lot like the Tucano, but dwells in the leaf litter!  

How could I resist doing this? Why wouldn't I want to go bigger?

I don't know if I can for much longer, lol.

So, picture a scaled-up version of the little tank...The main thing I'd do differently would be to slope up the substrate towards the rear of the tank, and really make sure that the Melastoma roots that I use are placed more towards the rear, giving the impression of a bunch of roots from marginal vegetation (species of Ficus and Leopoldina species are the dominant jungle plants in the habitat I'm interested in replicating), perhaps in a bit of an "arc", which will provide a lot of "front and center" swimming area- and a "basin" of sorts for leaf litter to accumulate.

I'm just scheming.

I did add some Corydoras pygmaeus to the mix, to create a little interest and some action (Yeah, the Tucanos are not the most active swimmers, lol).

The scale of a larger tank will allow me to create the more open, yet still complex  'scape that I am envisioning here. 

Oh, I'm liking this idea even more now. I can fully visualize this.

However, can I AFFORD it?


So, my little exercise in scaling up will cost me a lot of money, a little bit of enjoyable time, and provide unlimited awesomeness...

I think.

Yeah, it will.

Right? Maybe? Yeah.

Damn it. Stop me.

Or maybe not...enable me, then. Yeah! 


Yet, never forget that you can pull off a "big idea" on a small scale, and fall in love with it just the same!

That's the biggest takeaway from the "Tale of the Tucanos..."

Stay innovative. Stay creative. Stay restless. Stay bold. Stay motivated. Stay studious.

Stay just a little...weird...

And Stay Wet.


Scott Fellman

Tannin Aquatics 


Scott Fellman
Scott Fellman


3 Responses

Joshua E Morgan
Joshua E Morgan

October 30, 2019

Thanks :) The TDS would start at 20 ppm after the water change (I would also add a decaffeinated tea bag for every 2 gallons to supplement the tannins produced by the leaves, sticks, and peat moss already in the tank) and DROP to 10 ppm before the next water change…those plants were ravenous :O

Scott Fellman
Scott Fellman

October 30, 2019

Hi Joshua,

You’re a brave man! I think the lowest pH I’ve ever personally worked with was around 5.4 on a digital pH meter…I was able to hold it steady, but never got it lower (didn’t want to, lol)…But an interesting experiment nonetheless! Thansk for sharing your experience!


Joshua E Morgan
Joshua E Morgan

October 29, 2019

I have pondered setting up a tank for this tetra in the past…haven’t actually done it yet, but it is on the bucket list :)

I have had licorice gourami tanks before with such low PH levels…per two gallons of new distilled/rain water, I added a very small (something like a tenth of an eighth of a teaspoon?) of sodium bisulfate. The PH was at 4.2 after the water change and was still at 4.7 at the next water change.

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