Yes you can.Should you?

Pretty much every day, I spend a lot of time thinking about how to create better, more natural environments for our fishes. This involves studying not only their wild habitats, but techniques to successfully recreate many of they characteristics of these habitats in our aquariums.

And of course, these often involve some experimentation and even some risk. In the earlier days of my botanical-style aquarium work, I took a lot of risk as I played with different types of materials and ways to recreate some of the aspects of the natural habitats of my fishes in my tanks- and it didn't always go perfectly. It took time to perfect- or develop techniques that created better outcomes for the fishes.

I think it's a safe bet to say that no lover of aquariums ever wants to put his/her animals' lives in danger. However, when you're traveling into uncharted waters (literally!) and trying things that you and few other aquarists have ever done before, the element of risk comes into play.

The degree to which we as aquarists take risks is, of course, variable, and a personal thing. However, the idea that the aquarium hobby is completely without risk to our animals sort of overlooks the fundamentals by which we operate.

Just removing fishes from a stable, wild habitat and "acclimating" them to the conditions that we provide in a glass or acrylic box of water in our suburban living room is a significant risk, right? Fishes have evolved for eons to live their lives in a specific set of environmental characteristics. For example, characins and such from soft, acidic blackwater habitats.

And when we "force acclimate" them to the environmental conditions which are most convenient for us to provide, it's clear to me that we are adding a layer of stress to their existence.

Now, as we all know, many fishes have bred and reared for quite a few generations in environmental conditions that are dramatically different from those in which they evolved. Now, when we are able to breed, for example, a Cardinal Tetra or whatever- a fish which evolved in soft, acid water- in our hard, alkaline tap water, we hail the achievement and make the observation that these fishes are adaptable and have been "acclimated" to our conditions.

And it's hard to argue that point on the surface.

Spawning any fish is an achievement to be proud of; to be celebrated. We've helped a fish become some comfortable; so adapted the environment that we provided that it responds to our efforts by initiating eons-old "programming" to start reproducing....Amazing!

However, I can't help but wonder if there is a difference between "adaptable" and "stress free" or whatever. I mean, just because the fish lives, and even breeds, in conditions far different than it was evolved to live in doesn't necessarily indicate that the fish is "acclimated" to them.

Sure, the fact that a fish are spawning indicates that it's more or less "comfortable" with your conditions- yet, if you take the approach that spawning is an almost "automatic" thing for many fishes- a necessary survival strategy that assures that the population continues, it's as much a testimony to their tenacity as it is to our skills, right? 

Not to diminish the effort of talented breeders around the world- that's not the point here...

What I am getting at is the question of whether or not many fishes truly as hardy and happy in our "forced acclimation" conditions as they would be if maintained and spawned in the conditions to which they have evolved to live in. Have we been really able to "undo" millions of years of natural evolution in a mere few decades of (commercial) breeding?

Is the breeding a "survival-induced" stress response, as opposed to a grand tribute to our skills?

Perhaps it's a bit of both.

I realize that this theory will not go down well with pretty much everyone who breeds tropical fishes...and I want to reiterate that I am not questioning our practices. It's not, "Congrats! You've bred the rare Wild Discus in hard, alkaline water because the fish is fearing for its very survival! You were LUCKY! It's NOT about YOU!" I'm just curious what is physiologically happening to species of fishes over the long term, which live their lives in conditions significantly different than those they were evolved to live under.

Yes, my ignorance of genetics and physiology are showing. But it IS something to at least consider, right?

I mean, yes, you can absolutely "acclimate" a Neon Tetra to hard, alkaline water.  I won't argue that. Over time, however, will this reduce the overall hardiness or disease-resistance of the captive population? Will different genetic selectors come into play, essentially "modifying" the species from its wild form, in terms of it's ability to function as "designed" by Nature?

Would it be such a crime to provide more natural conditions for the fish, as opposed to forcing the fish to adapt to the conditions which we want to, or are are easily capable of providing?

Yes, this calls into question the practice of a century of fish keeping.

It goes against the grain of the "keeping fishes is easy" mantra that the industry needs. So Im totally aware of the skepticism and unpopularity that this idea might foster. I'm not saying that what we've been doing is wrong. And I know that the hobby has been able to expand and grow as much as it has because not everyone wants to keep animals that require dirty-brown water and 5.7pH.

I just wonder if, in our century-long efforts to make all sorts of fishes "more accessible", if we've added an extra layer of stress to their lives?

Bringing this all home, I am no longer amazed by the many, many reports and pictures of all sorts of fishes which come from soft, acidic, blackwater conditions thriving, showing awesome color, and reproducing freely when kept in these conditions in aquariums. I mean, it SHOULDN'T be a surprise, right? The strange dichotomy of the last several decades is that many (not all...) hobbyists have been successful in keeping and breeding fishes in "tap water" conditions- so much so that reports of hearing how well they're doing under more natural conditions are the big news!

Funny. It wasn't always like this...If you read classic aquarium literature (like Innes, etc.), you see what great efforts hobbyists went to in decades past to provide more natural conditions for their fishes in order to get them to thrive and spawn. As the hobby exploded, it seems to me like it became more about making the fish work in the conditions that were easiest for the bulk of hobbyists to provide!

Yet, the reports of interesting results keep trickling in from our community. Even though we're not hitting every single environmental touch point, we are checking a lot of boxes off, right?

I don't think it's a coincidence.

"Repatriating" blackwater fishes to the natural conditions under which they have evolved for many millions of years just makes sense, right? Is its the humic substances and Tannins, and the lower ph? I think so. Sure, most of us cannot possibly maintain the 3.9-4.6pH that some species are found under- but keeping them in a pH of 5.8-6.6 certainly must be better for the fishes long term than say, a pH of 7.8-8.2, right?

This argument can be made for all sorts of fishes which come from specific environmental conditions- like brackish water fishes, African Rift Lake cichlids, marine fishes, etc.

Something to ponder as you plan your next (or first!) blackwater, botanical-style aquarium. It's more than just a pretty display or a unique setup. It's far beyond throwing in some leaves and seed pods and watching the water color up, isn't it?

Now sure, an argument could be made that captive-bred fishes which we keep in more easy-to-provide" tap water conditions could evolve through selection to be better equipped to survive in a variety of conditions than their wild brethren, who hail from a very specific set of parameters, right?

Maybe? I'm still not 100% certain that a few generations of captivitve breeding can erase millions of years of evolution in specific environmental conditions...

It's an argument that can go many ways.

It's very much the art and science of providing fishes with conditions far more representative of those under which they have evolved than we typically have done. To us, it's a voyage of discovery- a grand experiment filled with surprises and challenges.It's not as easy as it looks. To us, it's a new experience, like doing something in a different way than we've taken for granted for so long.

To our fishes, perhaps-maybe- it's like...going home. Sort of?

Enjoy YOUR Journey, while facilitating theirs.

Stay creative. Stay resourceful. Stay bold. Stay experimental. Stay dedicated...

And Stay Wet.


Scott Fellman

Tannin Aquatics 



Scott Fellman
Scott Fellman


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