The South-American Knifefishes thread

[Marc van Arc]

There is not very much information on this group, which is scientifically known as Gymnotiformes. According to Silurus (HH), only one book on them has ever been published (Electric Fishes of the Continental Waters of America, Mago-Leccia, 1994). Googling for images of S-Am Knifefishes results in an abundance of pictures, including Asian and African knifefishes as well as several mormyrids......

I have found that quite some people here are interested in S-Am Knifefishes, but that there are lots of questions about all kinds of subjects wrt these fishes.
Therefore it may be an idea to gather all questions, (possible) answers and experiences (good and bad) in this thread, so they all sit in one place.

I will add some information myself shortly. Feel free to join in. Your opinion may be very useful/valuable to a fellow aquarist.

[apistomaster]

I have always been interested in SA Knifefishes although I have only kept 3 that are fairly common and a fourth if I can count the 24 inch/60cm Electric Eel I had.

1. Black Ghost(Apteronotus albifrons). Many times some reached 12 inches/30 cm.
They always became very tame and loved taking small earthworms from my fingers.

2. "Carapo" Knifefish (Gymnotus spp. One of the banded spp.) Mine was about 9 inches/~23 cm.
Mine was rather vicious. I shipped in 4 and they arrived in tatters. The one I kept healed very rapidly as they are known to do. I kept it with larger fish at first but I ended up keeping it alone as something of a pet. Easy to keep. It also loved small earthworms and blackworms, of course.

3. Glass Knifefish (Eigenmannia virescens). I kept 6 for about a year but I didn't see them often. They hid among plants, inside caves or under bog wood. They were in a fairly peaceful SA community tank and were easy enough to maintain but very shy. Even so, they are a good beginner's species and not expensive. Some live worms are appreciated.

I always wanted to try one of the long nosed knifefish but they are expensive and not always in good condition at first.
That is about all I have to add but I guess it's a start.

[Marc van Arc]

Here is a picture of one of my diggers/buriers, Gymnorhamphichthys rondoni. Not the best of pictures - these fish are very fast - , but you may get an impression. This one is feeding and they do so by putting their mouths into the substrate in a chicken-like manner. If things become too tense for whatever reason, they bury themselves completely.

(this picture was shown previously in the auchenipterid thread).

(this specimen buried itself rather sloppily)

[apistomaster]

Marc,
Those are the Knifefish that "got away" from me. One of the weirder ones I always wanted.
Great find.

[Marc van Arc]

That is about all I have to add but I guess it's a start.

Thanks Larry, there nothing wrong with a good start. And you may include the electric eel

[wrasse]

[coelacanth]

Look in great condition Richard, must be easy to care for...

One to avoid unless you have a huge aquarium is Sternopygus, easily top 1m in length, superb fish at that size but need aquaria around the 1000galls mark as a minimum. They do come in as youngsters and are very appealing at 6", but they eat and grow.

[wrasse]

[quote="coelacanth"]Look in great condition Richard, must be easy to care for...

Thanks Pete... they are and they aren't.
The main hurdle is to get them eating when they're new to your tank. To achieve that they do best in a species tank with no competition. Once they're eating well and putting on weight it gets easier.
Although glass knives will eat small live foods, the trick is to feed something that 'fills out' their stomachs and adds bulk... I found the best food for that is finely chopped earthworm.
Once they are eating a variety of other foods, alongside earthworm, they're ready to join a community of fish.

[nvcichlids]

i will complete my post this afternoon/tonight.

I am converting my 125 gallon community bar tank into a centipede knifefish (Steatogenys duidae) tank. My friend is bringing them in from South America this week. I hope to pick them up this weekend (pending his OK to release them.) Right now the tank has for plants vals, I will be adding amazon frogbit once my new LED light comes in. I will also be adding some sword plants, anubias and java fern to the wood. The tank has a decent amount of driftwood. (picture coming tonight). I intend to get atleast 10, if not more. 24 total fish are supposed to be coming in. Here are the tank specs:

Temp: 78
Filtration: Fluval FX5, Eheim Pro II 2028(I think..) plus 2 HOB's rated for 75 gallon tanks if needed.
2 x 300 watt heaters
Lighting: Currently a 96 watt PC light fixture (48"long) which creates enough light in the center and dark spots around the edge.
fine sand substrate with some small pebbles in places, few larger rocks
8 ish large pieces of driftwood

I hope to eventually keep the following in this tank:
10ish Steatogenys duidae
12-16 Silver hatchetfish
6

Farlowella sp

6

Loricaria sp

Thoughts/ideas for the eventual outcome? All fish but the hatchetfish will feed mid/bottom and are slow eaters, which to me would make little competition for food... I am completely open as I want the knives to be happy.

[naturalart]

Aside from catfish, knife fish are some of my favorite fish. I've kept 5 species total:

African knife (xenomystus nigri) Super cool fish. Most fish-like of the knives listed here in my opinion. Ate just about everything offered; staple, live or frozen. Once killed a paradise fish that wanted to challenge it. Kept 7yrs. Passed in a 3 day power outage.
Black Ghost (Apteronotus albifrons) Had it only briefly, knew it would get too big for my tanks and sold it. I think I observed that other fish could feel this fishes charge as they dodged or 'jerked' out of the way when the knifes nose got close. Has anyone else observed this?
Brown ghost (Sternacella schotti) I don't think I have good karma with this fish. It was a very nice fish with a relatively small mouth. The other nice thing is that this fish stays small (@4-7"according to scant lit.) My first purchase a heater blew up and cooked the fish. And a 2nd fish carried a 'superbug' that survived quarantine: wiped out a whole tank including my main S. shoutedeni of 15yrs.ARGG! Needless to say I won't be purchasing this fish again anytime soon.
Brown ghost (Apteronotus leptorhyncus) Very similar to S. schotti in appearance. This fish, according to scant literature, grows to @1ft/30cm. My fish was at about 6.5"/15cm, able to keep up with my other syno's. Fast, quick to the food. Able to handle/avoid conflict. I kept the fish for about 3yrs. Then I put it in with my S. waterloti's and after about a year it died. Not sure why but maybe waterloti's were too aggressive?
Zebra knife (Gymnotus pedanopturus) Quickly became one of my favorite fish. Very attractive, interesting behavior, quick moving. This fish was what I would imagine a smaller version of its larger cousins (electric eel or Carpo knife) would be like: semi-aggressive, sometimes a bully. But alas, a slow eater ('chewer'). It was definitely a piscivore, as it bit and ate a number of smaller 'dither' fish I kept with it. It lived for 4yrs and then something bit the tip of its tail off and that was the beginning of the end. It stopped eating slowly, and slowly wasted away.

The one down-side about all of these fish (except the X. nigri) is that they didn't like eating staple foods. They would eat them sparingly, and although flakes were probably the most acceptable, none were eaten with gusto. And in a community tank thats not a good thing for success. Live foods and frozen were the preferred choice in that order.
I'm of the mind now that the knives I've kept were not the best cohabitants for my syno's, or most catfish tanks for that matter (A. leptorhyncus might be an exception). I think they do better in specimen tanks, where they are the main fish. My 2¢

[Marc van Arc]

Brown ghost (Sternacella schotti)

Could you expand a bit more on this one? I can't find any reference to this species - except through Google, which refers back to this thread.
FishBase also doesn't list it, so I'm very curious.

[apistomaster]

Brown ghost (Sternacella schotti)

Could you expand a bit more on this one? I can't find any reference to this species - except through Google, which refers back to this thread.
FishBase also doesn't list it, so I'm very curious.

Same here. Never heard of these.
Maybe a case of mistaken identity? Were they different looking than Brown Apteronotus?

[apistomaster]

On a hunch, I checked in my copy of Freshwater Fishes of the World by Gunther Sterba, revised edition 1966.
Found them on page 362, Figure 515. Sternacella schotti. I'm 100% sure they are an abandoned synonym for the Brown ghost (Apteronotus leptorhyncus).

[Martin S]

Whilst knifefish don't tend to appeal, I saw a photo of one of these and found it very unusual, almost prehistoric!
Compsaraia compsa

Martin

[nvcichlids]

Searching for my camera ...

Martin, that one looks like... someone I know

[naturalart]

To marc van arc and apistomaster: Yes both of these fishes look very much alike, but, after both of these fishes passed, out of curiosity I preserved the bodies and examined/compared them later. Also I misspelled, its: Sternarchella schotti (Steindachner, 1868) according to Fishbase. The Apteronotus just looked different from the first Sternacella I had. It looked more like A. albifrons. but slimmer. And on comparison they were different. S. schotti is much slighter in build. The head is more elongate and narrow, and the anal fin is much shorter than A. leptorhynchus. which extends almost all the way to the caudal. The behavior was different also, with A. leptorhynchus being more bold and aggressive. Both of these fishes were roughly the same size. I can't remember now but if I took pics I will see if I can dig them up.

[apistomaster]

Hi naturalart,
Am I ever sorry that I claimed that I was 100% sure the Brown Ghost and Sternarchella were identical.
I also misspelled Sternarchella although Sterba had spelled it correctly in his 1966 edition of Freshwater fishes of the World I(A real collector's item, I special ordered it through a public library in 1968.)
I don't know why but Sterba described and his illustrations of Sternachella schotti and Apteronotus albifrons show a long and filamentous dorsal fin. I have never seen any Apteronotus spp. with such a feature. I wonder why they are shown with that long dorsal filament?
Furthermore, the illustration of Sternachella schotti, lacks the pronounced elongated head that is characteristic of Apteronotus spp. It more closely resembles the head shape of a Glass Knife.
So it does indeed appear to be the case that these are two different fish.

[naturalart]

Hi Apistomaster, completely understand. I don't own Sterba so can't speak to those pics but I ran into similar problems with other publications. I really had to sift through various pieces of info, book/web and otherwise just to get some support for what I was seeing with my own eyes. Appearently, there has been so little work done, or at least information available to the public, concerning these fishes that I bet most people don't even know they exist. If I hadn't had the bug to keep some of these fishes myself I would never have known either. Stack on top of that: time, changes in taxonomy and nomenclature, undesirable color patterns etc., and (I'm sure you're aware) you have many fishes buried in science and unknown to the public.
I would cut my beard if I could get my hands on the descriptions of some of these fishes. Do you know if there is a way to do that without paying large sums of money? Still looking for images.

[Shane]

Happy to look things up. I have the below as well as several other books that list individual species profiles.
-Shane

[Birger]

If anyone is putting together papers on these...I have just a few, most of these are fairly recent...maybe more if I look harder: (naturalert get your shaver out)

Comparable Ages for the Independent Origins of
Electrogenesis in African and South American Weakly
Electric Fishes-2012

Morphology and distribution of the cave knifefish Eigenmannia vicentespelaea Triques, 1996 (Gymnotiformes: Sternopygidae) from Central Brazil, with an expanded diagnosis and comments on subterranean evolution-2006

Three New Species from a Diverse, Sympatric Assemblage of the
Electric Fish Gymnotus (Gymnotiformes: Gymnotidae) in the Lowland
Amazon Basin, with Notes on Ecology-2005

A New Species of Gymnotus (Gymnotiformes: Gymnotidae) from Rio Tiquie´in Northern Brazil-Gymnotus tiquie

Evidence of the color pattern variation in populations of Gymnotus pantanal
(Gymnotiformes) from three streams in the upper
Paraná River basin, Brazil-2011

A New Species of Gymnotus (Gymnotiformes, Gymnotidae) from Uruguay:
Gymnotus omarorum-2009


Nesting and Paternal Care in the Weakly Electric Fish Gymnotus(carapo)
(Gymnotiformes: Gymnotidae) with Descriptions of Larval and Adult
Electric Organ Discharges of Two Species-2005


Three New Species of the Neotropical Electric Fish Rhabdolichops
(Gymnotiformes: Sternopygidae) from the Central Amazon,
with a New Diagnosis of the Genus-2010

New Rheophilic Species of Electric Knifefish from the Rapids and Waterfalls of the Lower Rio Xingu, Brazil (Gymnotiformes: Apteronotidae)-Sternarchogiton zuanoni,2010

Revision of the Deep-channel Electric Fish Genus Sternarchogiton
(Gymnotiformes: Apteronotidae)-2007


Birger

[bekateen]

Following Birger's lead, here's two more:

Maldonado-Ocampo, J.A., López-Fernández, H., Taphorn, D.C., Bernard, C.R., Crampton, W.G.R. & Lovejoy, N.R. (2013). Akawaio penak, a new genus and species of Neotropical electric fish (Gymnotiformes, Hypopomidae) endemic to the upper Mazaruni River in the Guiana Shield. —Zoologica Scripta, 43, 24–33.
DOI: 10.1111/zsc.12035
http://onlinelibrary.wiley.com/doi/10.1 ... 12035/full


Cristina Cox Fernandesa, Adília Nogueirab and José Antônio Alves-Gomesc. 2014. Procerusternarchus pixuna, a new genus and species of electric knifefish (Gymnotiformes: Hypopomidae, Microsternarchini) from the Negro River, South America. Proceedings of the Academy of Natural Sciences of Philadelphia 163(1), 95-118. doi: http://dx.doi.org/10.1635/053.163.0107

[naturalart]

Shane: would love a copy of that publication( is it french?) you attached if there's a way to purchase it and its not too expensive? But I would settle for any descriptions of any of the fish I listed above.
Biger: I am not trying to put anything together but would love info on any of the fish I listed in my tag.
Thank you bekateen for the links. Will be definitely digging into them.

[Marc van Arc]

Shane: would love a copy of that publication( is it french?) you attached if there's a way to purchase it and its not too expensive?

See my initial post for title and author. It is in Spanish (and English?).
And - to my regret - copies of this publication are scarce and (thus?) expensive. There was one for sale on Ebay recently for 150 USD.
However, the book being from 1994, it may very likely be outdated in several respects.

[amiidae]

Compsaraia compsa

Martin

Parapteronotus hasemani

[Martin S]

Thanks Ben - does the snout grow with age then? Your video shows a specimen with a short snout?
Is Compsaraia compsa an old name for Parapteronotus hasemani?
Thanks
Martin

[Marc van Arc]

Thanks Ben - does the snout grow with age then? Your video shows a specimen with a short snout?
Is Compsaraia compsa an old name for Parapteronotus hasemani?

Apparently these larger snouts are to be found in (sexually) mature males; they are used to impress or even to fight other males (afaik!!).

[Martin S]

Interesting - thanks Marc

[Marc van Arc]

Have a look at this:

Not my way of fishkeeping, but it gives you an impression of a species known as Compsaraia samueli, which has this gender difference.

Btw: Ben (Amiidae) must be our top expert given the enormous amount of species he has kept over the years. I hope he doesn't mind the following:

[Shane]

As Marc said, it is pretty hard to come by. Found my copy in a small bookstore in Caracas.
-Shane

[amiidae]

Thanks Ben - does the snout grow with age then? Your video shows a specimen with a short snout?
Is Compsaraia compsa an old name for Parapteronotus hasemani?
Thanks
Martin

Think the old name is Apteronotus anas. Compsaraia sp. are newly discovered species by Dr. William G.R. Crampton.

The elongated snout is related to sexual morph of a male.