February 26, 2017

Still haunted by the Black Ghost...

If your like me, you've got that "one fish" that never leaves your mind. The one that captured your heart at some point and simply never got out of your system.

Mine was the "Black Ghost Knifefish", Apteronotus albifrons. I'm not sure what it was that first attracted to me to this fish. The odd name, the amazing "look", or, after I had seen them in real life- their interesting behavior and yes- personalities! I remember seeing a pic in "Exotic Tropical Fishes" that had a "head shot" of the fish, and it had this oddly comical, yet altogether weird look- you know, all black...even the eyes...and it's mouth gave it a sort of friendly look. And of course, the references to the endemic people of the region believing that the souls of their departed ancestors resided in the fish and I couldn't let this one go.

And since I have't kept one in years, I thought that I'd take a quick look on what the fish REALLY needs and how best to keep it based on my accumulated experience and research. There must be a FEW things we had wrong about the fish, huh?

The only "down side" I ever though about with this fish is that it has the potential to hit put to 18" (45cm) or more in length, necessitating a large aquarium if you're wanting to accommodate the fish for anything approaching a natural life span (decades!). Like a 5-6 foot long tank is appropriate.

Now, this little piece is not going to be the usual "Keeping the _______ in the Aquarium" stuff. I simply can't write a good, solid article like that without all of the weird inferences and such that I like to make. Rather, let's quickly examine my beloved fish on the basis of what we know about it from science that can help us keep it happy in our aquariums!

As we all probably know by now, Black Ghosts are known to be weekly electric fishes, using their capabilities for navigation, location and identification of potential prey. This has been extensively studied by scientists. Like, really extensively...As a fish geek searching for information on the ecology of the fish, I was met with dozens of "way-over-my-head" style scientific papers on the fish's electrolocation capabilities. You know, the kinds of articles filled with exotic graphs and formulas, and nothing that tells you what kinds of water conditions the fish comes from? Yeah. That kind. Had to really dig for that stuff.

Although they are nocturnal predators, they're hardly what we'd call "aggressive" fish; instead, being rather shy and retiring! In fact, descriptors such as "peaceful" and "friendly" have been used over the years to (accurately, IME) describe the fish's temperament! This is, I think, a bit contrary to what most of us would immediately assume about such a fish, right? The popular perception for a fish like this is usually: "It's big, it's menacing- it's a Tetra killer and hell-raiser for sure!"

Even the swimming behavior of this fish is a bit cool. And well-studied, of course...From a paper by M.J. and S.J. Lannoo, 1993 entitled, "Why do electric fishes swim backwards? An hypothesis based on gymnotiform foraging behavior interpreted through sensory constraints." you find this gem: "The fish swims backwards (reverse swimming) which is characteristic of two foraging behaviors: searching for prey and assessing it. In assessing a potential prey item, it typically scan the prey from tail to head by swimming backwards, then ingest it after a short forward lunge. A scan in the opposite direction - from head to tail by forward swimming - would have the prey located near the tail and out of position for the final lunge."

Yeah, that about covers it.

Gut content analysis of a number of wild collected specimens from Paraguay and Peru indicated that the bulk of it's diet consisted of worms (annelids) and insect larvae, so yeah, that explains why they seem to love "black worms" and "blood worms" in the aquarium. Can they prey on small fishes? Sure- they have a pretty good sized mouth and a sophisticated electromagnetic navigation system, so yeah, they can locate potential prey items easily at night when they hunt...However, in no instance in any of the papers which I reviewed on wild-collected specimens of this fish did gut-content analysis of both juvenile and adult specimens reveal anything other than worms and insect larvae! Would I trust them with my "Green Neon Tetra" shoal in my aquarium? Umm, not likely, but I think they'd have a more difficult time with the more laterally compressed, vertically oriented characins, like Hyphessobrycon species and such! And, in general, if you keep them stuffed with worms, the likelihood of "Phee-Phee", your beloved Pencilfish, disappearing one night goes down dramatically, in my experience!

Now, because they come from Amazonia, the first thing that comes into mind is sluggish, acidic blackwater streams ('cause, like, that's everything in The Amazon region, right? NO SCOTT!) The reality is that most specimens are found in the wild in rapidly flowing waters of streams with a sandy bottom. And as we know from many of our past pieces on the substrates in this region, a lot of those sands are chemically neutral. However, much to my happiness, usually, lots of botanical debris and wood are found in these habitats.

So, if one were to recreate the habitats where these fishes are commonly found, it would be an aquarium environment with good water movement, a pH range from 6.0-8.0 (hello, that's all over the freakin' map, right?), and water temps typically around 77-82 degrees Fahrenheit (25-27 C). The tank would be at least 6 feet long, with nice white sand and a ton of branchy wood, lots of hefty botanicals, and probably some vertically oriented plant growth (like Amazon Swords or something equally as generic) Since blackwater is definitely a part of the fish's natural habitat, I'd be inclined to let it tint a bit, with some large leaves and other botanicals. And, of course, good water movement, probably provided by directed returns or external pumps like EcoTech Marine VorTech powerheads.

Tank mates would be larger characins, like Headstanders, and maybe a big shoal of fishes like Emperor Tetras or other laterally compressed, non-bite-sized Tetras. Oh, and a few smaller cichlids. Simple, easy, and "semi-cliched." But hey, the star of the show, the Black Ghost, is what this is all about, right?

And I'd feed a ton of blackworms and bloodworms. I'd have fat fishes in there.

Yeah, that's all Ive got this morning. Nothing earth-shattering. Just thinking of the Black Ghost.

Again.

So the takeaway here? Is there one? There is a lot of good information out there if you dig for it, and you don't need to accept what everyone says about a fish as the absolute last word on it.

Oh, and the fact that we gave it sort of "generic" aquarium conditions all of these years, and that those were surprisingly appropriate conditions for the fish based on its natural habitats does not make me bitter at all....I think it was just luck, lol.

Yeah. Right.

Stay engaged. Stay relentless. Stay excited.

And Stay Wet.

Scott Fellman

Tannin Aquatics