"Nature by numbers" and other parcels of knowledge that we should use to advance the state of the art...

Okay, I admit that I'm a huge fan of NOT chasing numbers and following absolute "recipes" to achieve success with aquariums. I mean, I know dozens of reef hobbyists who have literally driven themselves crazy trying to make sure that their calcium level is exactly ______ ppm, and their phosphate is ______ppm, or whatever. And yeah, I know a considerable number of freshwater guys who carry the same mindset. Like, matching the "numbers" from either some successful aquarium they admire or some article by some expert somewhere is the "Holy Grail" of success. 

And of course, objectively, we know it isn't.

Numbers are important, however. I'll give you that. And numbers don't lie or play favorites. They just exist. I'll have to admit, however, that despite my fear of "target fixation" when it comes to chasing environmental parameters (I've always said to find a range that you're comfortable with and don't let your parameters deviate from the range..), I do find some of the numbers from natural blackwater streams and other habitats fascinating, oddly compelling, and educating.

I realize, from the outset, that a tank is not a river, blah, blah, blah. However, there is much we can learn from understanding the environmental parameters of some of the will habitats we find so compelling.

In a recent study of Amazonian blackwater habitats near Manaus, Brazil, researchers came up with the following average parameters among the dozen or so sites surveyed: 

The streams had acidic waters (pH 3.7–4.8) with low conductivity ( 3.7 mS/cm, range 5 2.99–8.00) and relatively similar temperature (24.4 C, range 21.8–25.8). Waters were highly saturated in oxygen. Some other readings, such as the concentrations of various types of humic and fulvic acids present in the water was fascinating, yet possibly beyond our means to test for in an aquarium. Way over my head! Of course, if you're a scientist with access to proper lab equipment to test for this kind of stuff, just imagine the possibilities here! What can we learn from just this simple data set? How can we maintain pH levels so low and keep stability? We've discussed this before; it's possible and surprisingly straightforward to achieve with proper methods. And not all that difficult to maintain. It's just scary to many of us, because we've not done this before. We've heard warnings. 

But numbers...well, they don't lie. They just exist. It's up to us to see why, and to see what the numbers can do for us.

Numbers from studies of wild habitats can tell even us a few things about how many of each type of fish we could stock in a given aquarium and keep a sort of "natural ratio"  of fish types.  One could use survey numbers from a given Igarape or stream, for example, and with a little simple math, come up with some rough extrapolations about how many of a given type of fish could be kept in an aquarium display intended to faithfully replicate the habitat. This information is readily available if you look online, and is fascinating. From a fish species richness standpoint, a recent study of  just a few igarapes near the Amapa River in Brazil yielded the following numbers: 133 species were found, belonging to seven orders and 28 families. These include Characins (73 species), Silurids (27 species), Gymnotids (15 species), and Perciformes (14 species).

That's pretty serious diversity, with a preponderance of my faves, the Tetras! If one wanted to stock a "community aquarium" using-the the ratios as a guide, quite an interesting display could be created.  Like any interpreted numbers we use in aquarium design, you can't always take them literally and use them as your "roadmap"...However, they are a great source for determining just what the population density of given fish types is in an area. Granted, the raw numbers from field surveys don't tell the whole story, and there are numerous other factors, but they are an interesting starting point for "brainstorming" fish populations for your tank, right? Yet another example of the value of...well, values- in aquarium work! 


This quote from a paper by Mendonca, et al, tells me so many cool things about the habitats we love to replicate:

"In Central Amazonia, terra firme environments (uplands that are not seasonally flooded) are drained by streams that have acidic waters due to the presence of humic and fulvic acids. The waters are poor in nutrients and the forest canopy impairs light penetration to the stream surface, so aquatic plants are virtually nonexistent (Junk and Furch, 1985; Walker, 1995). In these oligotrophic environments, food chains are dependent on allochthonous material from the forest, such as pollen, flowers, fruits, leaves, and arthropods (Goulding, 1980; Goulding et al., 1988; Walker, 1991). However, small fishes are frequently abundant, and 20 to 50 species may occur in a single stream (Lowe-McConnell, 1999; Sabino, 1999)."

In streams, studies indicate that an increase in species "richness" is positively related to the habitat complexity and shelter availability as well as current velocity and stream size, and that substrate, depth and current speed are among the most important physical features in many bodies of water, which contribute to the formation of numerous "microhabitats", all with fascinating ecology, environmental parameters, and fish population diversity.  Stuff we've barely tapped into in the freshwater aquarium world yet!

The implications of this information for aquarists are profound and fascinating, and understanding, interpreting, and applying some of these numbers and concepts can potentially lead to some fascinating breakthroughs in aquarium work.

However, we have to "get out of our own way", first.

(FRIENDLY WARNING: This next couple of paragraphs WILL piss off some people, especially the guy who recently delivered to me a vitriolic, venomous attack asserting that we espouse "sloppy" and "undisciplined" aquascape design that is "truly an affront to most skilled aquarists." (I loved that part!) It kind of made me laugh...and made me a bit mad, of course. It's only my opinion, but I'm happy it makes people think.  I've asserted this position consistently, and I'll present it yet again, because I think it sort of applies to the overall theme of this discussion, so if it aggravates you, please skip this section or boycott "The Tint" or whatever makes you feel better...)

We're talking about numbers and stats and information, and about using this stuff to create aesthetically compelling, physically functional aquariums. There is always the danger of going too far, and falling into that cliche of closed-minded replication that is, in my opinion, consuming the aquascaping world, so use the information you find with a bit of interpretation...but make use of it nonetheless.

In my opinion, one of the great untapped resources for hobbyists our there is the numerous ecological studies being done on aquatic habitats worldwide. There is so much information out there which we can utilize to help create more realistic replications of natural habitats that it's almost tragic that we expend any energy at all trying to copy "Mountains of LIghtness and Being" by ________, or whatever ridiculous name is given to this year's "Intergalactic Aquascaping Championship" winner's aquarium, and held up as the ultimate in "aspirational" freshwater aquariums.  Yikes.

No disrespect to anyone intended, but, for goodness sake, nature has been doing it for millions of years, and is a trillion times better at it than anyone. Surely there is at least one natural habitat that you'll find almost as compelling as some underwater waterfall or "Middle Earth" scene or beach diorama scene, or whatever else it is that everyone is going "ga-ga" for  at these contests, which are presented to us THE pinnacle of aquascaping and aquarium design. Hello- they are just ONE category of aquarium...they represent one aspect-one interpretation of nature in the aquarium. Outstanding work, indeed- yet not the "end-all and do-all" of this stuff. Please take your heads out of your glossy contest brochures and rock-placement "rules" for just a second, and realize that there is far more to be inspired by (and apply your considerable talents to) than just this stuff. Like, this entire planet. Earth. I think you've heard of it?  End of rant. :)

Oh my God, that felt good! A bit mean-spirited, perhaps, but it felt good. And I think it was actually relevant to the topic.

So, back to our point...

Nature and taking a look at what goes on there is a very compelling starting point for designing functional, sustainable, and yes- aesthetically beautiful aquariums. You don't have to make sure that every twig, seed, and grain of sand is coming from the stream in Borneo that you're attempting to replicate. However, interpreting the data from field studies not only gives us "a track to run on" when attempting to replicate some of these habitats from a physical/aesthetic perspective, it gives us valuable clues as to the conditions which we need to understand, which might unlock the secrets of long-term maintenance and reproduction of numerous species. And of course, some of which have eluded our efforts to date, and even some who's survival in the wild may be questionable as well. 

By understanding the "numbers" and the "whole picture" of what goes on in the rivers, streams, bogs, igarapes, and other aquatic habitats of the world, we are in a much better position to create optimum conditions for our precious fishes, and to understand how to protect and preserve these priceless ecosystems, and relieve some of the pressures off of wild fish populations.

The numbers provide information. They provide a challenge. They throw down a gauntlet of sorts, daring us to see if we can free our minds from a century or so of aquaristic practice that says, "You can't keep these fishes" or "It's not safe to maintain these types of environmental parameters in an aquarium." There is a reason why these environments are successful, why life exists- and indeed- thrives- in them. And there are reasons why we're starting to see incredible results when replicating some of these environments in a more faithful manner than may have been attempted before. Numerous questions remain to be answered. Tons of data to be accumulated. Setbacks to recover from. Triumphs to savor.  Invaluable knowledge yet to be gained.

And you're right in the thick of the hunt! 

Stay bold. Stay firm. Stay focused. Stay open-minded.

And by all means...

Stay Wet.

Scott Fellman

Tannin Aquatics




Scott Fellman
Scott Fellman


2 Responses

Scott Fellman
Scott Fellman

January 20, 2017

Thanks for the interesting feedback (and as always, wonderful tank pics!), Rene!

I agree, the maintenance of what we in the hobby deem “lower pH” levels (like below say, 6.5) is not as difficult or scary as the popular hobby sentiment says it is. With good husbandry, like you suggest, stability within a range is achievable for long periods of time. And I think it’s great to see hobbyists such as yourself utilizing the information, like Heiko’s, which is out there for us to interpret. SO much to learn- so many concepts that we can learn from the natural habitats and apply on a macro scale to our aquariums, with the understanding that they are closed- yet very dynamic-systems. Looking forward to seeing more of your inspiring work in the future!


René Claus
René Claus

January 19, 2017

A late reply to a very interesting piece.

Quite a few years back I got hold of Heiko Bleher’s fantastic work ’Bleher’s Discus Volume 1". I was fascinated by his findings regarding water parameters and how many fish species live together in streams and Igarapé’s. This book has certainly had an impact on the way I ‘run’ my aquarium.

I started to use more leaves, branches and pods and I have maintained a ph between 5.5 and 6 successfully for years now. It is not difficult if you do regular water exchanges (with water that has always the same composition). This is of course easier in a bigger tank than in a small aquarium. The bigger the volume, the more stable your values will be.

Also in fish diversity I have not been afraid to have more than a few species of tetras in my tank. Many underwater recordings show this is a natural situation. Of course there are limitations and also here the volume of your tank is leading.

Anyways, I find these numbers fascinating. It’s a challenge to see how close you can get to a more natural situation in your aquarium without losing the balance.

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