The common thread of my fishy obsessions...

It's not very often that I become obsessed with a fish.

Oh, sure, it's happened quite a few times over the years, but when you "amortize" it out over a lifetime in the hobby, it's a shockingly infrequent occurrence for me! The fishes which have reached "obsession" level with me are varied, and the list includes some choices which, for whatever reason, simply grab me on some particular level. And when I sort of analyzed my favorites, some interesting "commonalities" became evident.

Each one was very well suited for the botanical-method aquariums that I play with, and look and behave amazingly in these systems.

The Sailfin Characin, Crenuchus spilurus, was likely the first fish which really grabbed me. It wasn't just the fish; it was the "whole package"- the meaning of the Latin genus name, ("guardian of The Spring" )the habitats it comes from, it's unusual, almost "cichlid-like" behavior, and the fact that it caught my eyes when I was like 8 years old, scrutinizing my dad's well-worn copy of the classic William T. Innes book, "Exotic Aquarium Fishes."

When I finally found these fishes, after literally three decades, I pounced and purchased a group. They did not disappoint! They are fascinating fish, with an almost creepy, mysterious presence about them. As anyone who's kept them can attest, they sort of "appear" out of nowhere in your tank, and disappear just as mysteriously, fading back into the shadows. Wow!

There pretty cool!


Honestly, if a fish could earn the moniker "cool", the Diptail Pencilfish, Nanostomus eques, would be it. It's absolutely not an overstatement to declare that these Pencilfishes have distinct personalities! They're not "mindless-drone, stupid schooling fishes", like some of the Tetras. (Sorry, my homies...Love ya' lots, but alas- you have no individual personalities...😂)

There's a bunch of unique aspects to this fish's behavior which I find enormously compelling. The Latin name of the species, eques, means "knight", "horseman", or "rider", in reference to this species’ unique oblique swimming angle. 

Ah, that "oblique swimming angle" thing. Yeah, they swim at an angle of about 45 degrees facing upwards. This angle is thought to give them an advantage in feeding. They see insects and such that fall from overhanging vegetation better than their horizontally-oriented buddies do. They get more food that way. Simple.

What I really love about these fish is that they are incredibly curious and obviously intelligent, checking out just about anything which goes on in their aquarium. You get the feeling when observing them that they are acutely aware of their surroundings, and once acclimated, are cautious, but pretty much fearless. A fellow hobbyist once told me she thinks they're the freshwater equivalent of Pipefish...and that sounds about right..I agree with that 100%!

Perhaps "Diptails" are my fave fish of all? 

And then came the "Black Ghost Knife Fish", Apteronotus albifrons. Again, it goes back to my childhood. Reading one of Herbert Alexrod's books, "Exotic Tropical Fishes", and the fantastic story about the legends behind the fish, and how it was revered by the South American tribes as a repository for the souls of their departed ancestors...

An intriguing and alluring tale for a young kid, for sure! They weren't farm raised like they are now. They were all wild-caught, which made them even more intriguing to me! And when I would actually see them in the LFS, they were (at the time) mind-bogglingly expensive, at like $25.00! (Hey, I was like 11 yrs old). Add to the fact that the fish was super-intelligent, nocturnal, and just plain weird looking, and it was destined to be a lifetime fave of mine. 


Killifish always held an almost irresistible appeal to me. I guess it was the habitats which they came from, their method of reproduction and egg incubation, and the fact that I rarely, if ever, encountered them in the fish stores. It was only after I joined the American Killifish Association at age 15 that I was really able to indulge myself. I tried and loved many different species, however, my all-time favorite was, and still is, Epiplatys dageti "Monroviae", a top-spawning fish.

It's regarded as a "beginner's killie" because it's easy to keep and spawn. It was the first killie I ever kept and bred, and almost everything about the fish appealed to me the minute I encountered it! In fact, almost any species in the rather subtly-colored genus Epiplatys captivates me, but this one remains my most loved killie!

I was never a big catfish person. I never really became obsessed with them the way some hobbyists do. Regardless, there was one species which grabbed my attention" Pecklotia compta, the so-called "L134 Leopard Frog" Pleco. I think it was the color pattern that grabbed me first. And then, upon learning more about them,  it was the smaller size, it's social habitats, its xylphagic dietary preferences, and its endearing behavior which lured me in.

I was first able to obtain a captive-bred specimen in 2016, and since them, I]ve never been without one. I currently have three of them, most recently acquired from my friend (and guest on "The Tint" podcast), master breeder Sumer Tiwari, and they have genuine "personality" and are absolutely some of the most entertaining fish I've ever kept- even though they seem to sleep most of the day!

You've gotta respect THAT!

More recently, it was the little Tucano Tetra, Tucanoichthys tucano, whcih grabbed me. A tiny, incredibly attractive little characin, hailing from a very specific habitat, replete with roots and leaves. There was virtually no way I could resist this fish, and creating a dedicated biotope-inspired aquarium for it was literally my destiny! When I did a little googling and found the type paper by Gery, et al,  with the original description of the fish, I knew that this one which I had to keep.

The paper included a few tantalizing tidbits about the locality where the fish was collected, and gave me a lot of good data that would help me re-create the function aspects of its habitat. And it required a commitment. These little tetras cost around $12 USD each- for a tiny fish, that's a LOT of money! And again, worth it in every respect. It was- and is-very easy to fall for this fish!

I have to admit one heretical thing: I am not a huge fan of cichlids. I know, that's like crazy to hear in this hobby, but it's true. Most of them simply do nothing for me. I see most as big, messy, mean, destructive fish. Oh, sure, I love Angels and Discus, but I have no desire to dedicate a large aquairum to them and their fussy habits (Shit, I'll take a stony coral tank any day over a bunch of prima donna Discus!). I've kept some Apistos- and they are cool, but they never really "grabbed" me.

However, the one that did, is the diminutive and interesting Dicrossus filamentosus, the "Checkerboard Cichlid". I think the reason why is the fact that this fish is peaceful, small, won't spawn every week, saddling you with 500 fry that you don't want, and the fact that it's from blackwater habitats, filled with leaf litter and tangled roots.  I have kept groups of these in botanical-method aquariums on multiple occasions, and they have always proven to be terrific additions to a peaceful community.

Perhaps the most recent addition to my "Obsession List" is "Valiant's Chocolate Gouarami", Sphaerichthys vaillanti. This fish came to my attention years ago, when studying the unique peat swaps and blackwater streams of Borneo. If ever there were a fish that was perfect for its habitat, this could be it! It was one of those fishes that, once I started keeping, I had to wonder why I had never kept it before!

Looking for all the world like a leaf at times, this small, peaceful, and altogether endearing fish captured my attention early on. When I decided to set up an aquarium modeled on these cool habitats, I emphasized leaf litter and branches, adding in the (for me) unusual choice of live aquatic plants (Mircorsorum sp., "Java Fern") to further keep their environment shaded, providing comfort for the fish and bringing out their natural colors and behaviors. 

It's a fish that might have changed my perception of Gouramis (which I always liked, anyways) from being "nice but not essential" fishes for my collection to "ones to obsess over!"



It becomes obvious to me, when I really start looking at things analytically, that my favorite fish choices seem to reflect a preference for specific habitats or ecological niches. Almost all of my faves tend to come from smaller tributaries and streams, with moderate to minimal current or water movement. These habitats are typically filled with leaf litter, branches, and submerged root systems. 

Many of my favorite fishes come from flooded forests (no surprise there..), or other seasonally-inundated habitats, and have specialized feeding, spawning, and foraging habits as an adaptation to these environments. Most are dimly lit, devoid of aquatic plants, with deeply-tinted water and lots of overhanging terrestrial vegetation. 

Most of them feed on allochthonous inputs (stuff that comes from outside the aquatic environment) like insects, small fruits, and flowers. Some display unusual dietary preferences, such as eating detritus, fungal growths, or lignin from submerged wood and roots. Pretty much all of them spend large amounts of time foraging.

Another common denominator of these fave fishes is that they are intimately tied to their environments. They move within, or migrate among similar habitats throughout most of their lives. As aquarium fishes, they categorically seem to do better long term when kept in tanks which replicate, to some degree, the function and form of their natural habitats. These aquatic habitats are profoundly influenced by the terrestrial habitats which surround them.


I think that this love for the fishes and the allure of their natural habitats is what drew me to the whole idea of botanical method aquariums. I believe that the environments themselves are as interesting and compelling as the fishes which inhabit them. I've dedicated a substantial portion of my life as a hobbyist to studying, understanding, and attempting to replicate the function aspects of them in my aquariums.


 My love for these fishes and their habitats is very much evident in the "DNA" of Tannin Aquatics, too.

It's what this whole thing is all about.


The other common denominator among my fish choices is that most of them are not exactly what most people would call "colorful." In fact, the bulk of them tend to be brown, black, or grey, or some combination of the three! Rather, they are "earthy" looking fishes, perfectly "designed" to compliment the environments from which they come. 


I think- actually, I'm certain- that this coloration thing is one of the other things which attracts me to many of them. This subtle, interesting, and remarkably complex coloration is something which I find compelling. From a purely aesthetic standpoint, the fishes compliment their surroundings, and become a part of it, rather than standing out and placing the habitat in the background. 

In the botanical method aquarium, it's great to have a little pop of color against the deep, rich colors of leaves, seed pods, and wood, and the tinted water. However, one of the surprising things I discovered years ago is that the more subtle fishes tend to "pop" more in blackwater tanks. Now, "surprising" not in that they display better colors- the environmental conditions we create obviously assist in that- but "surprising" in that they tend to catch your eyes more than you might expect.

Even the more cryptically-colored-and shaped fishes do this. In fact, they are somewhat more engaging in this setting than the more obvious, brightly colored fishes, IMHO.

(Farlowella vittata- another fave of mine...)

Now, some of these fishes do have flashier colors at times, which make them a bit more exciting to some people, I suppose. In the case of Crenuchus spilurus, the males have an extended dorsal and anal fin, and are larger and more colorful than females. Yes, "colorful" is relative here, but when you see a group- you'll notice the sexual dimorphism right away, even among juveniles.

What really gets me going with my fave fishes, though, is their behaviors- or how they interact with their environment. For example, the Sailfin Characin...

Individuals of this species spend a lot of their time sheltered under dead leaves, branches, roots, and aquatic plants. They tend to "hover", and don't dart about like your typical Tetra would. In fact, their behavior reminds me of the Dartfishes of the marine aquarium world...They sort of sit and flick their fins, often moving in slow, deliberate motions. Communication? Perhaps.

The Sailfin feeds during the daylight hours, and spends much of its day sheltering under branches, leaves, and root tangles, and is a mid-water feeder, consuming particulate organic matter, such as aquatic invertebrates, insects, bits of flowers, and fruits...Even the dietary preferences of this fish give you some idea of the habitat from which it comes, and gives you some inspiration to replicate aspects of it within the aquarium. 

Let's talk a bit more about how the environments in which fishes are found can affect their behavior, or how they interact with the aquarium that you create? 

My overarching suggestion?

Create the aquarium environment around the specific fish you want to keep.

Really.  I know, that is hardly ground-breaking. However, I think that lately, more tanks are designed around...the "aquascape" and the fishes are sort of "force fit" into them. I mean, "arches and tunnels" might be neat to look at, and fishes will swim through them...But what about modeling structures found in the habitats they come from? How many brightly-illuminated tanks with Green Neon Tetras or Kubotai Rasbora seem to overlook the fact that these fishes often come from tangled, turbid, even tinted habitats, with mostly terrestrial influences?

It might be kind of fun-and educational- to study where your fishes are found in the natural streams, lakes, and rivers they come from...and "work backwards." I mean, fisherman have been doing this for eons...why not fish hobbyists?

It makes perfect sense, because, well, we have a pretty fair collective understanding of how fishes interact with their environment, don't we? 

I think so.

Let's briefly discuss some of the more common features in natural bodies of water where fishes are commonly found...this might give you some insight into how to incorporate them into an aquascape. 

I need not discuss flooded forests all that much, because we've pretty much written more on this topic than just about anything over the years...Suffice it to say, my obsession with these unique habitats is well-founded; they are filled with amazing features, ranging from tree trunks to root tangles, to submerged terrestrial plants and leaf litter- all of which we can replicate in the aquarium in dramatic fashion.

And then there are flooded Pantanal meadows- essentially grasslands with low scrub brush and plants, which are flooded seasonally, providing a rich and diverse underwater habitat for a variety of fishes. These habitats, equally as engrossing as the flooded forests, are seldom replicated in the aquarium, for reasons that I cannot quite understand. Perhaps it's the "dirty" aesthetic which has thrown us off? Regardless, the fishes make use of the submerged grasses and vegetation for foraging and spawning among.

And of course, there are many features of streams and rivers that fishes LOVE to congregate in...Think about how you might consciously incorporate some of them into your next aquascape!

First off, a few "sweeping generalities."

Fishes tend to live in areas where the food and protection is, as we've talked about before. Places that provide protection from stronger current, and above-and below-water predators. Places where they can create territories, interact, spawn and defend themselves.

Bends in streams and rivers are particularly interesting places, because the swifter water movement will typically carry food, and the fishes seem to know this. And if theres a tree branch, trunk, or a big rock (or rocks) to break up the flow, there will be a larger congregation of fishes present.

So, the conclusion here is that, at least in theory, if you design your tank to have a higher "open water" flow rate, and include some features like rocks and large branches, you'll likely see the fishes hanging in those areas...

In situations where you're replicating a faster-flowing stream environment, think about creating some little "rock pockets", perhaps on one side of the aquarium, to create areas of calmer water movement. Your fishes will typically orient themselves facing "upstream" to catch any food articles that happen on by.

So, from a design perspective, if you want to create a cool rock feature that your fishes will likely gather in, orienting the flow towards it would be a good way to accomplish this in the aquarium. 

Wow, I can go on and on and talk about my fave fishes and the environments from which they come, but I think you get the picture. I'll be, that if you examine YOUR list of "obsession fishes" closely, you'll find some commonalities, too...I think it's almost inevitable! 

And one of the most exciting things about this hobby is that you can pretty much count on finding some new fish- or fishes- which will catch your fancy. Fishes that you likely haven't even thought about until the moment you stumble on them. Fishes which go from being "Oh, cool fish..." to "OMG, I HAVE to have that one!"

Which species will it be?

It's okay to be obsessed!

Stay excited. Stay curious. Stay engaged. Stay curious. Stay OBSESSED!

And Stay Wet.


Scott Fellman

Tannin Aquatics 



Scott Fellman
Scott Fellman


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