My curious obsession with finding livebearers from blackwater habitats...more candidates?

I have no idea what my obsession with this is, but I can't let go of the idea of some wild livebearer that can be found naturally occurring in blackwater habitats. If you're a fan of this column (and I know 2-3 of you might be), you are well aware of my absurd obsessions.

This one is really weird, though. And I can't let it go.

Blackwater livebearers...

I know there have been "transplanted" species that have been found in all sorts of places around the tropical world, but I'm still trying to find examples (or an example) of a species native to a blackwater habitat!

I don't care if the fish is grey, chromatically "uninspired", or just plain dull! I just think it would be cool to find one that could be biologically appropriate for one of our blackwater, botanical-style tanks!

Think I'm being childish or unreasonable? Perhaps, but I long ago gave up the fantasy of a bright red Dwarf Black Ghost Knifefish, and made peace with the "original ones" so I think I'm good with the Universe, lol.

One of the things I learned a long time ago, in doing some of the necessary homework on such an endeavor, you inevitably stumble on some fishes that you think are viable candidates, only to be schooled by Fish Base, experts, or other references that dash your hopes along the way. No different with this search. However, rather than utilize hobbyist-level resources, this time I went to the "dusty halls" (metaphorically, of course) of the scholarly ichthyological world. Remember my previous searches for the half-mythical "Amazon Molly"- the fish with the most tantalizing name? I researched the hell out of it, only to find out that the "Amazon" part of the "common name" was because of it's unique reproductive strategy- NOT it's natural range! 

And I didn't come up too disappointed this time! I found some genera which may actually be non-coastal-confined, non brackish-water fishes!

It's a start, at least!

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 for the last century, let me burst your bubble right away, oaky? 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 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!"

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

Gotta get me some of these! 

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 ugly wild Mollies. (Of course, 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...). Actually, 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 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... Ones we have played with before! Getting close, 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! And it 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: "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.

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

The reality is that many of the livebearers encountered in the trade and often in the wild were introduced from other areas. Because of their adaptable nature, you're likely to find them i na range of habitats, from brackish water (yay!) to soft, acidic water. However, it seems to me that most of the species come from more coastal locales, and the water might be "colored" through silt and mud, as opposed to the blackwater that geeks like me are fascinated with.

And of course, inevitably, after all of this tedious research, I've once again found that there are tons of cool obscure livebearers that we could keep in brackish water "estuary" tanks! So, all is not lost. 

Inevitably, some livebearer fan out there somewhere will have some tips for me (Likely, something sorta of reminiscent of, "Stay out of this shit, Fellman- you're research is flawed and your fantasizing here...") about some of these fishes. It may just be that there are no truly blackwater livebearers, I mean, there are other similar fishes which could satisfy my obsession (hello, Rivulus!), but I have this "thing" about finding some livebearers that fill the profile here!

Maybe you have a lead on some? Maybe it's right in front of my face? 

Perhaps. Perhaps not.

Either way, it's been fun looking for something that likely doesn't really exist. It's the kind of fish geek stuff that makes you- well- a fish geek- right?


It sure does.

And I sure am a fish geek. Perhaps a stubborn, delusional, obsessed-with-the-wrong-thing one...but a fish geek through and through. And I own a company that sells "twigs and nuts" to fellow geeks.

Not so bad, actually. Nope.

Be a geek. Follow your weird obsession. okay? And don't be afraid to share them.

Stay relentless. Stay curious. Stay diligent. Stay passionate. Stay excited.

And Stay Wet.


Scott Fellman

Tannin Aquatics 












Scott Fellman
Scott Fellman


1 Response

Marc Weiss
Marc Weiss

January 10, 2018

Fluviphylax are egg laying cyprinodonts,and are considered killifish.
Almost thirty years ago, I found many F. pygmaeus in a dense forested area, of relatively calm black waters of the eastern Rio Purus ,Amazonas Brazil.. The iris of the eye is fluorescent white, shining in the dark water.The fish is brown with some blue on the bottom. Vey attractive, but tiny fish. No one had a fine mesh net, and I was eventually able to catch one in a coffee cup. It was let go. (The F. pygmaeus was identified by Ruud Wilderkamp, I had no idea what they were. The white eyes in the black water caught my attention.)
Fresh and brackish water"Amazonian" livebearers would be in the genus Micropoecilia, I was never in the areas they are found, so I don’t know whether they venture into black waters.

Leave a comment