The continuing search for blackwater livebearers...Why do I put myself through this?

Do you ever get going on some tangent in the hobby, and just keep researching something that you either have a "hunch" about- or just become flat-out obsessed with? Well, I have just such a strange obsession going on.

It has to do with livebearing fishes. Specifically, ones from blackwater habitats.

Yeah, 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 blog (and I know 2-3 of you might be), you are well aware of my absurd obsessions.

And as you know, other than some guppies or the occasional Molly- I've never been a big livebearer guy! I can scarcely even identify anything other than the "big three" (Guppies, Mollies, Platies...)- really. I mean, maybe a Gambusia or some others...

IRRELEVANT FACT: I did have Zoogoneticus tequila once, though!

( Zoogoneticus tequila- Image by Loury Cedric- used under CC BY-SA 4.0)

Anyways, this obsession I have is really weird, though. And I can't let it go. Like, why am I so obsessed?

Yeah, blackwater livebearers...

I know that 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?

I mean, perhaps, but I long ago gave up the fantasy of there some how being a bright red Dwarf Black Ghost Knifefish, and made peace with the "original one" so I think I'm good with the Universe at this point, lol.

It's interesting, to say the least...

One of the things I learned a long time ago is that, 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 just schooled by Fish Base, experts, or other references that dash your hopes along the way. No different with this search.

However, rather than utilize only 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! 

That totally took the metaphorical "air out of my tires", as they say...

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 and all of the famous livebearer experts for the last century, let me just 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 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... Ones we have played with before! 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...

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 in a huge 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, often obscure livebearers that we can keep in brackish water "estuary"- themed tanks!

So, all is not lost. There is always something cool to think about...

Inevitably, some livebearer fan out there somewhere will have some tips for me (Likely, something sorta of reminiscent of, "Stay the f --k out of this shit, Fellman- you don't understand these fishes, your research is flawed- and your fantasizing here...") about some of these fishes. And look, it may simply 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 species that I haven't thought of? Maybe it's right in front of my face? I mean, I know there is probably some guy out there who found a group of Endler's that were released into a blackwater pond in Florida or something...that's not what we're talking about here...We need something naturally found in this type of habitat.

Is one out there, swimming contentedly in some tannin-stained blackwater somewhere in South America?

Perhaps. Perhaps not.

Either way, it's been kind of 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.

This is pretty good.

My advice to you- as if you need it?

Be a geek. Follow your weird obsessions. Whatever they might be... And don't be afraid to share them.

Stay obsessive. Stay relentless. Stay curious. Stay diligent. Stay passionate...

And Stay Wet.


Scott Fellman

Tannin Aquatics 





Scott Fellman
Scott Fellman


4 Responses

SCott Fellman
SCott Fellman

December 08, 2019

Ohh, good one, thanks! I’ll have to research that one more…and see if it’s available somewhere!


Kris Haggblom
Kris Haggblom

December 07, 2019

You might check out Hemirhamphodon bysus – a halfbeak from Borneo. This is from It inhabits lowland forest and peat swamps in southern Sarawak, Malaysian Borneo and is currently known from Sematan, Lundu, Bau, Batu Kawa, Matang, Bako, Serian, Balai Ringin, Gedong and Sri Aman.

Scott Fellman
Scott Fellman

October 22, 2019

Oh- Good one! I can appreciate it being touchy! Sounds liek the “Chocolate Gourami” of the livebearer crowd, right?


Joshua E Morgan
Joshua E Morgan

October 21, 2019

How about Priapichthys nigroventralis? Not an easy species to find (or keep), this is a glowing orange livebearer with blue eyes. It comes from water with PH in the mid 6’s. Very prone to dying off at the slightest mistake, unfortunately…in particular very sensitive to velvet (their body color doesn’t help).

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