Stuff we need to do...

Like so many of you, after many decades in the aquarium hobby, it's sometimes hard to plot my "next move"- what ideas I want to play with. I mean, sure, the hobby can be as simple as just obtaining a tank, filling it with some water, plants, rocks, and BLAM!  You have an aquarium...

On the other hand, it's supposed to be fun, and many hobbyists enjoy the process of researching, planning, sourcing. A lot of us love the idea of pushing out further and trying some completely new and exciting....Or just different. Or even, the same as what we've done before, just different.

That being said, it's always fun to try something different, isn't it? And sometimes, we could use a creative push in the right direction. I think that it's helpful to curate a little list of stuff that we need to do.

Here are a few ideas which I think we as hobbyists should play with a bit more, and the "problems" that need to be overcome when incorporating them into our hobby.

Brackish Water Aquariums

Yeah, brackish. Again. The "poster child" for misunderstood, underserved, and uninspired!

PROBLEM: It suffers from misconceptions and a void of information and examples.

Brackish water (arguably possessing a 1.005-1.010) is a sort of "middle ground" that for decades in the hobby has been well-travelled. And widely mis-understood. I've played with brackish water for almost two decades, in between reef keeping and my blackwater stuff, and in researching both the hobby work that has been done and the scientific materials out there on the wild habitats, have sort of made this conclusion that it's simply been an afterthought, at best for aquarists.

Although there is a good amount of scientific information on brackish-water habitats from which brackish water fishes come, but comparatively little hobby information out there outside of a book or article  here and there. , (with the rare exception of some biotope enthusiasts) we've sort of distilled brackish water aquarium aesthetics down to white aragonite sand, a few rocks, and maybe some hardy plants...and it's been mired in that aesthetic hell for decades.

And then there is that "perception" thing...

I think that the perception among many aquarium hobbyists was that brackish is more tricky to keep than freshwater, and easier than a reef tank, yet offers little in the way of excitement on first glance. I mean, the fish selection and availability has not been exactly stellar, with many dealers hesitant to stock brackish fishes for simple lack of demand and interest.

And quite frankly, many fishes that have been perceived to be "brackish" by hobbyists are either actually from pure freshwater habitats (I'm thinking about certain Glassfish and some Rainbows), or have some populations that are from brackish (which are seldom imported). And then there are those fishes, like Mollies. which are Euryhaline (capable of tolerating a wide range of salt concentrations), with the majority being found in pure freshwater. Salt, in many cases, is simply used for health purposes.

(P. sphenops by Hugo Torres. Used under CC by 2.5 es)

Okay, that's the problem, as I see it.

The solution, IMHO, is to bring a bit of new thinking to the approach which takes a more realistic look at how brackish water habitats really are. 

A system that embraces natural processes and functionality...And just happens to have a different aesthetic, too! Less emphasis on "sterile" white sand and crystal-clear water, and more emphasis on a functional representation of a tropical, brackish water ecosystem: Muddy, nutrient- rich, filled with mangrove leaves, and stained a bit from tannins. Beautiful in a very different, yet oddly compelling way.

Enter the age of the botanical-style brackish-water aquarium.

It's a bit different.

It's about husbandry. Management. Observation. Diligence. Challenge. Occasional failure.

Yes, you might kill some stuff, because you may not be used to managing a higher-nutrient brackish water system. You have a number of variables, ranging from the specific gravity to the bioload, to take into consideration. If you've never used salt mix before your skills will be challenged, but the lessons learned in the blackwater, botanical-style aquariums that we're more familiar with will provide you a huge "experience base" that will assist you in navigating the "tinted" brackish water, botanical-style aquarium.

It's not "ground-breaking", in that it's never, ever before been done like this before. I just don't think that t's never been embraced like this before...met head-on for what it is- what it can be, instead of how we wanted to make it (bright white sand, crystal-clear water, and a few rocks and shells...).

Rather, it's an evolution- a step forward out of the artificially-induced restraints of "this is how it's always been done"- another exploration into what the natural environment is REALLY like- and understanding, embracing and appreciating its aesthetics, functionality, and richness.  

Figuring out how to bring this into our aquariums. That sort of thing. WIth more hobbyists playing with more realistic interpretations of brackish water habitats, we'll see more discoveries, more collective experiences, more refinement of practices...and like, more breakthroughs!

Replications of the habitats of wild livebearers

Now, wild livebearers are definitely a "thing" for many hobbyists. There is something super cool about the many, many different species of fishes like Goodeids, Xiphophorus, Heterandria, etc...And even more cool is the idea of replicating their natural habitats in a more realistic manner.

PROBLEM: Finding detailed information about the wild habitats of many species is a bit difficult to come by.

Okay, again, if you scour scientific literature, you can find out some information about the habitats where these fishes occur. However, you often will only find a passing mention, or a reference to a site. It's up to you to do even more research on the specific locale and kind of go from there.

I think that replicating the natural streams, lakes, swamps, and other bodies of water in which livebearers occur naturally is an interesting endeavor! And the habitats which they come from might just surprise you.

And there are a bunch of interesting ideas and approaches you can take; Brackish, straight fresh, and...blackwater.

Yes, blackwater livebearers! 

Now, lest you get too excited that there is a super-colorful livebearer out there, which lives in blackwater and has somehow evaded the hobby and all of the famous livebearer experts for the last century, let me just burst your bubble right away, okay?

Most of these are (in no particular order):

A) grey

B) not typically found in the aquarium hobby

C) really obscure

D) did I mention, grey?

That being said, I have a few that do intrigue me for some reason.

My first target genus is Fluviphylax, which contains five described species, not one of which anyone who is not a native fisherman, lifetime member of the American Livebearer Association, or doesn't have the letters, "PhD" after his/her name has even heard of- let alone seen! These are rather interesting fishes, distinguished by really large (relative to their body size), almost "creepy-looking" eyes, the absence of a gonopodium in males, and the usual complete lack of color seemingly common to pretty much every obscure fish in the world...

(Does it get any better? Fluviphylax in all its glory! Image by Clinton and Charles Robertson, used under CC BY 2.)

Despite the creepy eyes and complete lack of anything resembling "color", they are tantalizing to me, because the genus is apparently endemic to the Amazon and Orinoco region, including habitats like lakes, swamps, and "floating meadows." Appropriately, the first species listed in the genus is Fluviphylax obscurum, which drew me in from the start- and its native range is listed as the "Upper Rio Negro basin!"  

Oh, that's interesting! Of course, that's a big geographic area, and just because it's in the "region" doesn't mean it's all decomposing leaves and dark, soupy water... That being said, some references have it listed pretty far inland, well into "blackwater country", so...

Maddeningly, no reference I could find to any type localities mentioned the specific water chemistry of the collection sites. However, one cool thing is its diet, which always makes me smile:  Its diet is described as "autochthonous micro-algae and detritus and allochthonous invertebrates. We know what that means, right? Yeah...Music to my ears! 

Gotta find me some of these! 

Now, interestingly , I was also told be some people definitely in the know, that Fluviphylax is actually considered an egg-laying killifish... So, I guess my information might be flawed or misinterpreted...This would not be the first time, of course. We may have to take this one out of the "livebearer" category!  And of course, one hardcore scientific paper I stumbled on provided all sorts of chromosomal analytics and stuff way over my metaphorical "pay grade", but couldn't clarify this.

In fact, the discussion section included THIS line: "All species but the type Fluviphylax pygmaeus have been described in late 1990’s, and much remains unknown about the biology, taxonomy and systematics of this group of fishes."

Helpful, huh?

Regardless- this is an unusual species of cyprinodont...whatever it is!

My next candidate group has to be the genus Pamphorichthys. The genus contains six described species, all of which look like- well, how can I say it- they look like butt-ugly wild Mollies. (Of course, 75% of people outside the livebearer-geek community would immediately tell you that, "All wild Mollies are kind of ugly", so I'm staying out of that debate...). Interestingly, they are more closely linked to Mollies than any other type of livebearer, so even with my relative lack of knowledge about Mollies, maybe I'm on to something!

(P. hollandi. Image by Marcelo Fulgencio Guedes Brito)

They are true, undisputed livebearers, which is cool, and the interesting part about these fishes is their range. The genus name means "Fertile Fish", which might tell you something here! In addition to The Amazon/Orinoco/Guyana region, its members are found in The Tapajos and The Xingu! Habitats, that, although not really "blackwater", are kind of in our "softer, acidic" target range... Getting closer, huh?

One type locality mentioned for P. hasemani is "Paraguay River drainage", also kinda close to what we're thinking about, water-wise, perhaps? The typical pH of the Paraguay River is 5.8—7.4 in the upper part and 6.3—7.9 in the lower part of the river. So, like all over the place, but... And, of course, the Paraguay River ranges from being described as "sediment rich" water to clear...I mean, pics I've seen of this river look "brown", but...

However, no exact mention of "blackwater" specifically as respects to the habitat of this fish in any of the research I've found thus far...


And then we have Alfaro cultratus, which hails from Costa Rica, Panama, and Nicaragua, and is supposedly found in creeks, streams and other waters with an average pH of 6.8, and a hardness of around 5 dGH...It's a fish that is kept in the hobby, and even has a "common name"- the "Knife Livebearer'. I know a number of livebearer specialists who swear that this species does better and looks better in softer, more acidic water...particularly its reddish highlights in the scales and fins (No, seriously, it has them!). And it does have a certain "look" that would make it fit in with those flashier fishes, doesn't it?

(Alfaro cultratus. Perhaps the best candidate yet for a "blackwater livebearer?" Image by Haplochromis, used under CC BY-SA 3.0)

Could this be our baby?

It could be our best match yet!

I mean, Fish Base has this intriguing passage about this species: "Inhabits waters of low to moderate velocity, between 0 and 300 m elevation. Lives on creeks of more than 0.5 m deep, in ditches and near shorelines of large rivers. Generally swims in small groups at a depth of 20 cm. Insectivorous, the young eat mainly aquatic insects and the adults feed specifically on terrestrial insects."  One collection locale was listed as "..a rapidly flowing rainforest stream." 

Intriguing? Yes. A perfect fit? Hell, no. I mean, a "rain forest stream" could mean anything, right? Yeah.

Sigh...I'm likely really trying to fit a "square peg" in the proverbial "round hole", but it shows you the depths an obsessed guy will go to...

And then, there's this:

A while back, I received my long-awaited copy of "Fishes of the Orinoco in The Wild" by our friend, Ivan Mikolji (NOTE TO READERS: GET THIS BOOK! PERIOD. JUST GET IT- you'll thank me.), and was pleasantly surprised to see a section with some members of the Family Pociliidae!

More clues!

And, on page 278 in this must-have book, what to my amazed eyes did I see but our good friend, Poecilia cf. reticulata, AKA, the Guppy? Well, specifically, a variety known as the "Orange Line Guppy." One that I have seen before! This was huge!

And, sure enough, Ivan relates his enchanting first encounter with these little beauties, in a blackwater habitat- the Rio Morichal Lago in his Native Venezuela!

He described that they tend to stay in schools in the most shallow parts of the river, and that they, "do not venture more than 1.5 meters offshore where the water gets really dark and larger fish live."

(Rio Morichal Lago, Estado Monagas, Venezuela. Image by Cesar Perez)

That was all I needed to hear, but the accompanying photo really let this sink in: A small group of these fishes in tinted waters, with a gently sloping sandy bottom, covered in decaying leaves, twigs, and botanical materials! Ivan indicates that the pH in this habitat ranges from 4 to around 5.5- undisputedly acidic; conditions which we seldom seem to associate with livebearing fishes! 

They're beautiful little fish, with the males possessing an unusual pinkish-orange  horizontal line across the body, with a small almost black marking at the caudal peduncle. They also possess a smaller, less distinct black spot behind the pectoral fins. The females are "generic livebearer silver-grey."

I've also seen these fishes on sale from various breeders listed as "Campona Guppies" or "El Salto Guppies", collected near Ciudad Bolivar, 50km east of El Tigre in Venezuela, in the same Rio Morichal complex Ivan refers to in his book. Curiously, despite the common moniker 'Guppy", most of the hobby listings I've seen indicate that they are Poecilia wingei ‘Campona’ (you know, like "Endler's Livebearers), so there is much taxonomic confusion, to say the least!

All that being said, these are very intriguing fishes to me. Whatever the hell they're called.

 So, yeah, if you look hard enough, you'd be surprised at what you can find...


An utterly engrossing group, with amazing colors, diverse spawning habits, and adaptability, the attributes of killifishes should make them some of the most popular fishes in the hobby!

Yet, they're most definitely NOT.

PROBLEM: The general hobby doesn't have a good understanding of just how amazing these fishes are.

To me, the reasons above and many others have kept them "top of mind" for me over the years, even though I may not always have kept them consistently.Their relative difficulty to obtain has sort of added to the mystique for me. That and the fact that they typically will not have "common names", and are generally referred to by their scientific name, followed by a geographic locale and some other numbers makes them all the more alluring to me!

Hmm... "geographic locales" never scared anyone here, right?

Yet, I digress... These arcane species names don't help in the splashy, superficial "Insta world" of social media that we've created I the 21st century, I admit.

I mean, shit- there's like 0.000034% chance that a fish with a name like "Austrolebias arachan, UYRT 2015-04" is EVER gonna knock off the Cardinal Tetra or Angelfish and crack the "Hot 1,000" list of the most popular aquarium fishes, right? 

Yet, the precise Latin descriptors and type localities bely a secret to those who do the work...they give us information of incalculable value about the specific biotope/habitat from where the fish hails from. And to those of us who strive to replicate- on many levels- the wild habitats from which our fishes come from, this stuff is pure GOLD! 

(Chromaphyosemion bivittatum, pic by Mike PA Calnun)

And of course, one of the things I like best about killifishes is that many come from habitats that would be perfect for us to replicate with our skills and interest. Hobbyists who keep killies may not be as into the aesthetics of blackwater or botanical-style aquariums as we are, but nonetheless, they understand the dynamics of using natural botanical materials like peat moss, coir, and leaves to stimulate spawning and provide health benefits for their fishes!

Perhaps what also attracts me to them is the fact that they are (for the most part) small, super-colorful fishes who have managed to adapt and evolve to life in very unusual environmental niches, like puddles, small creeks, temporary pools- stuff like that. And of course, these are extremely "botanically-influenced" habitats, replete with leaves, soil/mud substrates, branches, etc. The killies are intimately linked to the characteristics of their habitats, and the seasonal changes which impact them. 

It's utterly fascinating.

(Kwango Province, Congo- Image by Thomas Minesi)

Interestingly, we have seldom, if ever seen them being kept in anything other than a dedicated breeding setup with spawning mops and bare bottoms. I think this has perpetuated the popular perception that they require the dreaded "specialty conditions" (hobby vernacular for "weird shit that's hard to do..."), and the need for 200-tank setups that will turn you into the aquarium version of the "crazy cat lady", thus smashing your interpersonal relationships to pieces. And of course, this pretty much scares the crap out of the typical armchair hobbyist.

That's where we come in. 😎

I think that attempting to replicate, to some extent, the aquatic habitats from which they come would go a long way towards making these adaptable and attractive fishes more popular in the hobby! And instead of 300-odd plastic shoeboxes filled with killies, you might have like 6 different "biotope-inspired" aquariums for killies (I say that now...). That could help ensure a bit of "domestic tranquility", right?

How you manage your interpersonal relationships is your call- but I think we can help make it a bit easier with our approach, right? 😆

(Fp. amieti, pic by Mike PA Calnun)

Sure, some killies may be shy, skittish, aggressive, come from soft, acidic water, brackish(!), or whatever- but the last time I checked, we have community of skilled, adventurous aquarium hobbyists playing with blackwater, botanicals, and the availability of all sorts of "twigs and nuts" to create all kinds of specialty aquariums.

And we are into some pretty geeky stuff, ourselves, right? That makes us THE community to tackle fishes like killies in a new way.

Now, there are literally hundreds of species of killies to choose from, running the gamut from top-spawning species which deposit eggs in floating plants, to the famous South American and African annuals, which deposit their eggs in the mud and sediments at the bottom of the temporary pools which they inhabit, so it would be impossible to "generalize" a biotope-inspired "generic" setup for all these types. However, one could create a more-or-less "generalized" setup for say, species which come from small African streams and pools. 

Granted, this is different than what "hardcore" killie breeders will do- and not as efficient for breeding as setting them up in bare tanks/plastic sweater boxes with spawning mops- but it's a different way to enjoy these unique fishes, and to celebrate the unique ecological niches from which they come! I simply don't think that we as killie fans have done a great job "de-mystifying" these fishes and their needs. As mentioned above, we have seldom, if ever see them being kept in anything other than those "utilitarian-looking" dedicated breeding setups with spawning mops and bare bottoms- and lots of people assume that is THE way.

It's not. It's just a DIFFERENT way.

Another of the many things that we need to do. Another of the many directions that we can go in our hobby. It's all important. It's all fun. It's all stuff that "moves the needle" forward.

We've all got something to contribute when we tackle this "to do list" and get some cool stuff done!

Stay excited. Stay resourceful. Stay diligent. Stay inspired...

And Stay Wet.


Scott Fellman

Tannin Aquatics 



Scott Fellman
Scott Fellman


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