Tip-toeing the Tapajos and the idea of replicating "clearwater" Amazonian rivers...

With all sorts of hobbyists playing with botanicals in their aquariums, it's understandable that they want to utilize them for creating different types of aquatic environments. Although we spend a lot of time waxing poetic about blackwater aquariums and replicating all sorts of cool blackwater habitats from around the world, the fact is, there are numerous "clearwater" habitats with slightly acidic water, dynamic fish populations, and incredibly inspiring niches to replicate in our aquariums.

As we've discussed repeatedly, it's entirely possible to keep botanicals in an aquarium and completely control the tint of the water. We receive this question all the time, so I will defer once again to my personal experiences. We've done this "anti-tint" botanical thing many times over the years, most recently last year in what is now the blackwater aquarium in our office. Yes, it was a painful experiment for this blackwater lover, but I stuck it our and enjoyed all of my leaves, pods, and other botanicals in the vaunted "crystal clear, blue-white water" of hobby legend. It just took a little activated carbon, and a lot of "dealing with it" on my part, before I came to my senses and went "back to black..."

So, back to the wild for a bit. 

One of the more popular clearwater rivers in Amazonia for hobbyists to replicate- or, at the least- keep fishes from, is the Rio Tapajos in Brazil. It's the fifth largest tributary of The Amazon, and accounts for about 6% of the water discharged into The Amazon.

This interesting river is home to over 325 documented fish species, with more than 60 being endemic to the river itself. Many of them have only recently been discovered, and scientists think that there are probably hundreds more species residing in the river yet to be cataloged. Yeah, pretty rich fish diversity, right? As you might expect, the Characins seem to dominate the fish diversity spectrum, followed by the Loricariidae and Cichlids.

(Moenkhausia pittieri by SOK, used under CC BY SA-4.0)

Although the Tapajos has low levels of dissolved solids and relatively low conductivity like a blackwater rivers, yet the pH is not significantly acidic; rather, it's typically between 4.5-7.8. - quite a range, huh? This river is subject to seasonal inundation, which means that the water level increases dramatically (like 4-5 meters!) during the rainy season. Like many rivers, it encompasses a wide variety of habitats, ranging from near "whitewater rapids"-type conditions to slow-moving driftwood "snags", to mud/silt/sand bottom areas of modest water movement, and even areas with lots of rocks and aquatic plants.

All this means is that if you're into the whole "precise biotope" contest aquarium game, you're going to have to specify exactly what area of the river and what niche you're attempting to replicate, or the judges will express their significant dissatisfaction with you...

So, let's just say you're the typical, slightly-more-than-casual lover of biotopes, but you don't want to be so hardcore as to match every rock, stick, and seed pod to some geographic locale on the Tapajos. What do you do? Pretty much what we've always done as fish geeks: Design a tank around the fishes you intend to keep, and 'scape it and manage its characteristics accordingly. So, if you're intending to feature the L-Series catfishes, for example, it's best to research the specific region of the river your species comes from and work backwards. Woah. Earth-shattering.

Suffice it to say, you can take a large amount of "artistic liberty" in your replication attempts, and still end up with something that works for your fishes- and for you. (This mindset will now officially ban me for life from any biotope competitions, but hey- I've got other stuff in my life, okay?)

And you're kind of in luck, because there are so many fishes found in many different niches within the river that you can almost pick any one, design a tank around its specific needs, and end up with something really cool!

Personally, I find great interest in some of the areas where you're apt to find a variety of cichlids, such as the much-loved Geophagus. These fish, collectively heaped into the popular moniker of "Eartheaters", really appreciate finer-grained substrates, less than 1mm, so they can do their digging thing.

(Geophagus brasiliensis by Christoph, used under CC BY SA-3.0)

And yeah, since they move stuff around with these activities, you'd want to go with "beefier" aquascaping materials, such as more durable seed pods, driftwood, small rocks, etc. And yeah, we DO have a botanical pack that we've developed specifically for the "Geos", featuring a selection of materials that are a bit more durable, with a few "grazable" (my word!) softer ones, all of which are  somewhat less inclined to impart tremendous "tint" to the water if prepared properly.

 If you're inclined to keep Loricarids, the "sweeping generalities" that we discussed above are perfectly applicable! Of course, if you really want to be hardcore about finding out exactly what habitat you should replicate for your "L134 Lepoard Frog", Peckoltia compta, for example, do a little research on where the type specimens were collected. You'll get some seriously detailed information: "Brazil, Pará, Itaituba, Pimental, rio Tapajós downstream from the confluence with rio Jamanxim, 04°41'06''S 056°23'07''W."  All of this is well and good, but you'll have to dig deeper, unless you have a good friend or family member who happens to live nearby and can clue you in.

In the case of my beloved "Leopard Frog", the specimens were collected in moderate to fast flowing waters, over a rocky bottom.  Okay, helpful. Yet, you'll dig deeper and find that the fish is commonly found in more still water, usually over rocks and wood tangles in this habitat, with a smattering of botanical materials. Plants are less common.  So, you're kind of back to square one, finding a "common denominator" to work with- moderate water flow, mostly rocks, a few pieces of gnarled wood, and probably a fine-grained sand.  Had I done this ahead of time, I certainly wouldn't have added this fish to my blackwater, largely leaf litter-enhanced aquarium...but she seems none the worse for it...

And that's kind of how it goes with the Tapajos. A lot of different habitats to play with...the key attributes are clear water and typically sandy bottoms.  Both of which are perfectly compatible with tossing in some botanicals if you want. 

Where are we going with this? Well, sort of all over, really! The Tapajos, and other clearwater rivers, are classic examples of watercourses of the world where a lot of our beloved fishes hail from- and they are as diverse as the fishes themselves, offering many possibilities for replication, from "generic" to incredibly precise, depending upon your interests. It's hard to arrive at "one habitat" that exemplifies this, or any river. 


*Do research.

*Chill out a bit.

*Use activated carbon.

*Build the 'scape with the fishes in mind.

*Incorporate all sorts of botanicals, except maybe leaves.

*Chill out a bit more.

*Do whatever you want.

Gee, this might be my least helpful piece yet...or maybe it isn't , because the whole point is to simply approach aquascaping and water tint and such in a manner that you enjoy, taking what you like and applying it...not by adhering to some clinical standard of what is and is not "correct", as intimated by "them."

Unless you're into that, of course...

Okay, I think we've went nowhere long enough. I have orders to pack and worlds to conquer.

Stay bold. Stay creative. Stay resourceful. Stay...calm.

And Stay Wet.

Scott Fellman

Tannin Aquatics 

Scott Fellman
Scott Fellman


2 Responses

Scott Fellman
Scott Fellman

June 21, 2021

Hey Heidi,

Happy you enjoyed and got the point. There IS a lot of science, but it’s super important to chill and enjoy this stuff, too! The guys at AI are super knowledgeable people, and Im glad they hooked you up with our blog/podcast!

Heidi Dugger
Heidi Dugger

June 18, 2021

This is the most helpful thing I’ve read in a hot minute, and I read quite a bit! I really appreciate the emphasis on chill out a bit in between sciency bits. Aqua Imports, in beautiful Boulder Colorado, sent me when I mentioned that I’m a black water noob. Thanks to you both! Shine on!

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