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FAQs on Fishes called Knifes (Black, Chocolate Ghosts, Glass...) 2

Related Articles: New World Knifefishes, GymnarchusNotopterids/Clown KnifefishesBlack Ghost Knife, Electrogenic Fishes,

Related FAQs: Knifefishes 1, Knifefish Identification, Knifefish Behavior, Knifefish Compatibility, Knifefish Selection, Knifefish Systems, Knifefish Feeding, Knifefish Disease, Knifefish Reproduction, Electrogenic Fishes, & by Group: Aba Aba Knives Chocolate/Brown Knifefishes, Electric Eels (Knives), Glass Knifefishes, (Eigenmannia), Gymnotus carapo, Notopterid Knifefishes (Clowns...),


Ossa knifefish    11/20/17
On second thought, about my earlier message.
I may actually be interested in Ossa knifefish. Did some quick research, although there is virtually no info on them other than they can grow really huge and are mainly predatory.
<Yes; Rhamphichthys rostratus gets to a meter in length>
The Ossas are around 12 cm at the lfs. Right now, i have 3 tanks big enough to house them. The 150 gallon planted tank: I see them in YouTube kept in planted tanks, however, this is a high tech, co2 infused and very bright aquarium. There is a big piece of bogwood with Anubias and java fern on the corner. It really is a big piece which gives shade to about 1/5 of the tank area. This is where the phantom Plecos come to hide during the day. Could this be sufficient for the Ossas?,
<For... more than one? For how long?>
there is dense vegetation also, the substrate is not that bright. I reckon the biggest problem will be the feeding. The tank has a lot of occupants: Rainbowfish, tetras, Kuhli loaches, a Kribensis quartet and so. Competition for food is high, and then comes the fact that the Ossa needs live or frozen foods, also he will likely be staying near the bottom while most of his tankmates will be at the surface feeding.
<According to Fishbase, live on "benthic aquatic invertebrates">
The tank is big, but i doubt the tank has enough microfauna to feed Ossas. I've seen scuds and some time ago i dropped some daphnia. Every now and then i see a single daphnia swimming. There is life in the substrate, but how much? i don't know. Also, can they eat my smaller, red phantom tetras? because they are my favorites.
<Will/would have to be fed specifically; foods (if frozen; defrosted, rinsed in tapwater to remove liquid nutrients; placed right down on the bottom near the knife>
The other aquarium, a long 40 gal which is housing Ancistrus cirrhosus and Ancistrus ranunculus, an Acara diadema and some Thorichthys maculipinnis, although these are smaller than 6 cm, they will be moved later to a bigger aquarium. This tank does not have much competition, but it is significantly smaller than the 150 gal, likely has no substrate fauna either, so feeding will be a challenge, again.
There is also a 15 gal long heavily planted tank again. However, this tank just has a female guppy, 2 black phantom tetras and 2 green fire tetras. Besides that, there is a thriving colony of cherry shrimp. For all i know the shrimp can help in feeding the Ossas! and really... i have not shortage of shrimp...
<.... this tank is too small>
Only other option i can think of is a 10 gallon, they would be by themselves though, so i can arrange the tank to fit their needs.
Any of these cases would be momentary, i would be setting a proper tank for them later, maybe mid-late February.
As for food items, i culture Zophoba, mealworms, daphnia, Microworms and have thriving colonies of shrimp and also breeding Poeciliids, probably have around 60-70 freshly born fry at any time.
There is not much info on these. Can they be taught to take flake/other prepared foods?
<I doubt it>
what about frozen pieces of shrimp and so?
<I'd ask what the shop is using. Have to be appropriate (small) mouth size>
their mouth look so small, they don't look like they could even eat my smaller tetras (red phantoms), maybe suck in platy fry.
<Maybe not>
Just realized that my fish room stays very cool, surprisingly. Unless using a heather, tanks stay between 22 and 24C during the night. 25C max during the day. during the hottest days of summer it may reach 28C. Telling you this based on the profile that they prefer cooler waters.
<Is a coastal species; likely hardy re temperature and water quality>
Thanks again.
<Welcome. Bob Fenner>

Rhamphichthys rostratus, aka ossa knife fish 9/10/09
Does anyone know about these knife fish?
<A bit. A large Rhamphichthys species, to 100 cm, upwards of 50 cm typical, that feeds almost exclusively on benthic invertebrates including insect larvae and worms. Comes from coastal parts of northeastern South America where the water isn't too warm, so a maximum temperature of 25 C is recommended. Nocturnal; hides in caves and hollow branches during the day.
Primarily a food fish of relatively little value as an aquarium fish.>
Are they appropriate aquarium pets with similar needs to other South American knife fish?
<Because all South American Knifefish are electric fish, they are generally best kept one species per tank. In most cases the smaller species are kept in groups of six or more while the bigger species may be kept singly (though it is questionable whether they occur singly in the wild, likely not). Like other South American Knifefish, water quality needs to be excellent, but water chemistry is relatively unimportant provided extremes are avoided. The water current should be reasonably strong>
Do they need a soft substrate for their "nose"?
<Certainly beneficial. There is some evidence the "snout" or "nose" on these knifefish is an example of convergent evolution with African Mormyrids such as Elephantnoses, both types of fish using the structure to locate prey hidden in the sand. Gravel or sharp sand would likely damage the skin on the snout, making the fish vulnerable to secondary infections.
Since these fish are intolerant of copper and formalin, your options for treating parasites and infections are limited mostly to salt and antibiotics. Prevention is better than cure!>
I found very little information about them.
<Indeed, not widely kept.>
One of these mysterious fish has turned up at my local fish store. Any and all information would be much appreciated. Thank you in advance, Anna
<An interesting species for the advances aquarist. Could be combined with non-bite-sized midwater characins, but otherwise not really suitable for the average community tank though. Cheers, Neale.>

Info on Sternarchorhamphus macrostomus. Platyurosternarchus (formerly Sternarchorhamphus) macrostomus   8/23/07 Hello all. <Hi.> Well, I do a lot of the ordering at a store I work at, and I managed to get in two Knifefish under the name 'elephant knives'. The species appears to be Sternarchorhamphus macrostomus, but the problem is I cannot locate ANY information on this fish outside of the limited info under the picture in Axelrod's Atlas. <Likely one reason is that the genus is considered to be Platyurosternarchus by some. Using this name will bring up more hits in databases and the net, although not as much information as you would certainly like to have. In addition a proper ID is not easy. Also have a look on other members of the Apteronotidae or Gymnotiformes in general (http://www.wetwebmedia.com/FWSubWebIndex/knifefishfaqs.htm).> I only managed to get 2, and I cannot get more, so I'm thinking very seriously of getting them for myself. <Certainly very rare if this species.> I was wondering if anyone here has any information on these fish. <Not much, but Id expect it to be similar to more common ghost knives and other neo-tropical knife fishes. Likely will attain 15 and is slightly electric. Would not keep it with other electric fishes. Many occur in groups and use their electric organ to communicate, so I would not separate the two specimens you have. Small fish will probably be eaten. Plenty of floating plants would help them to feel comfortable, since many are nocturnal. Males are usually much larger. Breeding possibly can be triggered by imitating rain season.> They are feeding well on frozen/thawed bloodworms right out of my hand, and as far as I can tell are showing no aggression towards one another. <Great.> Thanks for any help you can give! <Have fun with your new fish. Seems you are doing some pioneer work. Marco.>

BGK   1/27/06 Hi there, I have a 35-ish gallon tank, to be moved up to a larger one soon. I was planning on keeping some smaller knife fish in it for now, however all my LFS's only carry black ghosts. I am aware that these grow to ~20 inches, am I right? <Rarely more than about eight inches overall in captivity> Are there any other more suitable knifes for my tank? <... would have to know more re> It is well planted, with driftwood, etc., (lots of hidey-holes) and I have several medium sized (~3 inches) Gouramis, along with some small, 2 inch clown loaches, a whiptail cat, Pleco, and CAE, <This last may become trouble in time> as well as some cichlids. <... sounds pretty crowded... S.A. Knifefishes are not ready "fighters" for food, space> I am planning also on introducing some Cory cats, African butterfly fish, a dojo (weather) loach, and possibly (but not likely) an elephant nose. <Then skip on the knife/knives> I realize the elephant nose should be alone in a tank of my size, but could I keep more than one BGK (small, ~3-5 inches)? How fast do these guys grow? Will there be any conflict between them, or will the elephant nose and BGK's electric field thingies bother each other? <Yes> As well, what about their feeding habits? Will their nocturnal behaviour keep one or the other from getting food? I also have some medium sized angels, but I don't think they'll be too much of a problem...if you guys have any better suggestions to my choice of fish, please tell me. My LFS's all tell me that everything will work out fine, but then again, they would tell me Neons are compatible with knifefish if it meant I would buy them. I do kind of have myself set on knife fish, because of their method of movement, but please tell me if you do not think I have adequate housing for these fish. I realize I am asking quite a bit right now, so I thank you in advance for anything you can do for me -Eddy <You need more tanks Eddy... Bob Fenner>

Re: BGK   1/30/06 Thank you for the quick response. I will be keeping my CAE in a different tank, it is getting pretty aggressive... I think I'll skip on the knives till I get at least a 50 or 60 gallon, will this do for the knives? I'll stick with the cories and butterfly fish for now. Thanks, Eddy <Welcome my young friend... Have you considered working part time at a local fish store... or volunteering (if one's nearby) at a public aquarium? Bob Fenner>

Knifefish Fin Problem   1/10/06 Hello, I've had my Black Ghost Knifefish and Blue Gourami for well over a  year now. My water parameters are all normal. The Temp. is 79 degrees. They are  in a 29 gallon soon to be in a 55. My problem is that I have just noticed that a   few of his fins are torn right near his tail. Is this a result of fighting? <Possibly> Will  it heal on it's own? <Should... with the move to larger quarters, good care> Will he be all right or will he need any kind of medical  attention? Thank You <Be careful with treatments around the Apteronotid Knife... often more toxic, hazardous than worthwhile. Good clean water, decent nutrition should cure all here. Bob Fenner>

Black Ghost Knifefish, Quarantine - 10/17/2005 Greetings and salutations! I would like some advice on caring for a Black Ghost Knife. I brought home a healthy specimen at around noon, and put him in a 10 gallon quarantine. <Ah, good. Quarantine is essential with new stock.> He was a beautiful deep black with off-white markings, roughly 4 inches. It's now 2 AM and the entire front part of his body has faded to a silvery color. <Go to sleep! Actually, he could just be fading to more nocturnal colors.... though I cannot recall having seen them change to lighter colors at night - but many fish do.> It's as if his black is fading completely away! My QT water parameters: Nitrite/Ammonia-0ppm, Nitrate-10ppm, temp-78F, slightly hard water, pH 7.2. <What pH was he in at the store? He could be suffering from a bit of a shock from change in pH and hardness.... They hail from waters of low-ish pH and low-ish hardness, so this may be part of the issue. At this point, however, I would not change what you have - a steady pH is FAR more essential than a "perfect" pH.> The tank is bare but for 2 PVC pipes. <Large enough for him to enter and hide in?> The tank is in a private room, and the light is off. The fish is swimming "normally" (like an excitable drunk). Fed some frozen brine shrimp earlier, but he seemed to be spitting them out. <He may not eat for a day or so.... but likely you will need to start him on live foods. I could be mistaken, but I believe these animals are only wild-caught and not at all bred in captivity.> I read that these fish are very sensitive and their rich black color may fade due to stress, but I was wondering how common it is for this fish to fade so drastically in this short period of time!!! <Mm, 14 hours isn't really a short period of time.... a fish turning pale at night can do so in minutes. 14 hours is more than plenty of time for the fish to get stressed, as well.> I will keep a sharp eye (I can't sleep the way it is). Should I add a bit of salt? <No.> Stress-zyme? <No.> Is there possibly a metal in the water that Aqua-safe is not removing? <Not likely that this is what's harming the animal, if anything. I would suspect a poor reaction to a sudden change in pH above all else.> I always appreciate your help, thank you in advance. ~M <All the best, -Sabrina>

Black Ghost Knife Compatibility, Disease - 10/12/05 Hi - <Hello.> I have a black ghost knife that was bought recently - about 5 inches long. He's in a community tank and unfortunately we forgot about the nippiness (is that a word??) of our Serpae tetras. <Uh-oh.... Err, *I* say 'uh-oh', but Bob (whom I'm visiting currently in HI) says there really isn't a compatibility issue here. I, personally, would be a little nervous about these two species together.> They have bitten off the end of his tail!! RIGHT TO THE 2ND BAR!!! <I do agree with Bob here that the Serpaes may not have been the sole contributor here - please check your water quality. Maintain ammonia and nitrite at ZERO, nitrate less than 20ppm, with water changes.> I treated the water with this thing called MelaFix for any bacterial infection that it might get( I'm in Australia - hopefully you know what that product is!!) <I do.... and though MelaFix (extract of the Melaleuca tree, or "tea tree") does seem to have some mild antibiotic properties, I would not rely on it alone as a medication for anything severe.... furthermore, I have seen evidence in my own fishes that it may be a little (or a lot) irritating to the fish.> He seems OK but I'm worried that he won't survive without the tip of his tail. Is there any thing else I can do to help him out?? <Maintain optimal water quality, and (though Bob and I disagree on the Serpaes!) keep him separate from any fishes that might bite or nip at his wounds until he's healed. The end of the tail might not grow back in its entirety, as well.> Also we recently moved house (about 3 weeks ago) and obviously had to transport tank and contents. It's a 4 ft tank (180litres) so we took about 1/2 the water with us and didn't clean filters out etc the ph is 7, the nitrites are 0.1 and the ammonia 1.2. to me this is high as it is normally 0. <Dangerously so.> Is there any thing I can do to lower ammonia levels. I haven't done a water change since we moved. <Water changes alone will fix this.... and it is urgent that you do.> Thanks for your help... Tam <Any time, Tam. Wishing you well, -Sabrina>

Black ghost knife fish 10/12/05 Hello guys just thought of saying thank you for all you useful info. <And thank you very kindly for these words.... It is great to hear/read this, some times.> I had a 55 gallon fresh water planted tank that was running for about 2 and half years. Fish in the tank: 1. a black fin shark (5") <Gets very, very, VERY large with time....> 2. a black ghost knife fish (8") 3. 2 adult angels, a marble and a golden (3" in diameter) 4. a rope fish (8") 5. a Pleco (5") 6. a stripe Raphael cat (4") 7. 3 tiger barbs (2 ½") 8. 2 ruby cichlid (2") <A touch overstocked for my tastes! Just be sure to keep up with water quality....> It wasn't until two months ago that I started having trouble. I acquired the 3 tiger barbs from the fish store when I normally go. Some lady came in and left two containers full of huge fish, between them was the three tiger barbs that I took. I introduced them to my tank without using a quarantine tank the way I should have. <Ohhhh, no.> One of the barbs became really fat. After reading a little I thought it could have been pregnant. About three weeks later I noticed that it had cloudy eyes. They cleared after a couple of days, but it came back and ended up dying a few days later. <Many possibilities, here; including mycobacteriosis....> Now one of the two barbs left started chasing the other and nipping on its fins until it almost had none. So I decided to get three more tiger barbs to keep them in odd numbers.  <Very aggressive nippers; watch that they don't harass the other fish as well.> A few weeks later I noticed my golden angel had this white dust on its body. After reading I found out it was velvet. <Aaaaaargh! Serious bummer.> When I looked around the tank the black fin shark also had it. I did a 40% water change and treated the tank with copper. <Oh, yikes! Toxic/deadly to some of the fishes in your tank.> Kept the temperature on 80*. Next day the angel and the shark died and most of the other fish after that. I decided to get a 20 gallon set up and keep the fish that weren't sick (black ghost knife fish, the Pleco, and the two ruby cichlids). <Surprising that the knife and Plecos survived the copper - delicate fish.> I've done the constant water changes to fight the ammonia spike and it's been pretty good so far. But now I notice that the black ghost knife fish bottom jaw looks like it is decaying. I wish I could show you a picture. <I wish so, as well, but am pretty certain this is water quality related. Be sure to maintain ammonia and nitrite at ZERO, nitrate below 20ppm, with water changes.> Could you please tell me what could be wrong now? Cordially, Ivan. <Though it's entirely possible that these fish did contract velvet, I would lean more toward an environmental issue with this deterioration. Improve the water quality, and observe very, very closely.... and, as you've learned, in the future, quarantine all newcomers to your tank. Wishing you the best, -Sabrina>

Training a black ghost knife fish  9/22/05 Dear Mr.  Fenner, I have a black ghost knife fish that I have had for a month.  He is now about 7" long and very healthy.  He eats flakes in the morning and at  night, occasionally I give him some freeze-dried Tubifex worms.  What I  would like to know is how you teach them to eat out of your hand. He seems to be  a smart one he figured out the flakes were edible on his own.  If you know  how to do this I would really appreciate it. Thanks for your  help, MDM <Try feeding small amounts of meatier foods, more frequently, particularly just with some light on outside the tank (not in... too bright). Takes time, patience. Bob Fenner>

Just general random questions about Knifefish... heh Hey there! First off, I'd like to say that I'm completely Wowed by your extensive and totally awesome information and help on all sorts of fish and such. It's been a great help to me, and quite interesting to read (heh, I'm a bit dorky =P) <You're in good company here> I've had fish for all my life really, and I'm always trying new stuff, so naturally, when I spotted an odd looking fish, I snatched him up right away. Probably not the most brilliant of moves, but the shopkeeper assured me that he was what I could handle properly. (we've known each other for some time...) He sold him as a "Chocolate Ghost Knifefish". Upon proper research.... I couldn't find a single thing on them, really. ^^" I can't quite determine the species of fish he is (or she really, I haven't found many websites that are too helpful with sexing Knifefish.), but he LOOKS like a Black ghost knife... but with a longer face, brown-ish, and a yellow stripe and a white dot for a tail. He doesn't match up with Brown Knifefish either, he just...isn't. Are there such things as Chocolate Ghost Knives, or is he just a special brown? <Mmm, there are a few species of Apteronotids this could be. Most often sold is Sternarchella schotti: http://www.fishbase.org/Summary/SpeciesSummary.cfm?ID=48027&genusname=Sternarchella&speciesname=schotti> It's been a good couple months since we got him, and he seems very healthy and quite lively and happy. We've been feeding him frozen blood worms, but I've recently wanted to change it up a bit, too. I heard full grown brine shrimp aren't particularly nutritious though...can we feed just hatched, or is that too small/meager to last them? <The latter> I heard frozen krill was a good choice; compared to blood worms, where does that stand? <A mix of worms, insect larvae, crustaceans... live, or frozen/defrosted will do> When there's a downpour around our area, we often can find earthworms and such wriggling about, and our old fish gobble those up. However, we've been concerned that they may either lack nutrition, or possibly still have chemicals from landscaping/lawn work, is that a concern? <Yes> We often eat shrimp and seafood at my house, and though I know fresh shrimp are quite delicious and probably great for them, are the ones at supermarkets and such fresh enough? <Yes> You know, the ones laid out on ice, that are already dead? <These are fine> Or will only the live ones, until the hour before you eat, okay? <Will learn to take bits of these> Can they OVEReat? <Can, but not common> He seems to bloat really easily while he's eating, and because I'm concerned with him overeating, I normally give the rest to our other fish. However, the few times he does get to try and eat a lot, he seems to stop himself. Do they always stop themselves before they explode =P, or should I be careful with feedings? <One should always be careful here> Since he's been with the same tank for a while now, but I suppose I should check in while I have the chance, right? He's about 7+ inches, in a 46gallon tank. A blue Gourami, a gold Gourami, a red-tailed shark, a Pleco, and 2 angelfish. The fish are all about 4-5 inches in length. He's not terrorized by any of them, never seen a mark on any of them, asides from the Gouramis always having spats between themselves. Any problems with these? <Should be fine> The tank is well planted, with aged driftwood, a ton of leafy plants, an excellent&powerful filter, more plants, and err...more plants. =) No little tunnels for the Knifefish like I've read about having, but he seems to like the plants enough anyways. Should we find a suitable tunnel, anyways? <Mmm, not necessarily... I like transparent... glass "chimneys" or plastic... for viewing... but the plants are fine> Wow. Typing wayyyy too much now, sorry! ^^" For now, my mind has run out of pathetically inane questions to pester you with, so until later.... Thank you for all your help! <Thank you for writing, sharing. Bob Fenner>

Black Ghost Knife Won't Eat I bought a black ghost knife  week back and gave it a small place to hide. Since then it has been hiding inside and very few times, twice in fact, it came out in the night. Apart from this it does not eat anything. I feed it in the night to discover that the food is still floating in the morning. Will it take time to get set in the tank or is it sick? There were small molly fry in it which  I bred and it has not touched them. Is there anything wrong with it ? Is it a strong or a delicate fish? I do water changes once a week. pls advice <Your black ghost knife fish is indeed a nocturnal fish. Try small live invertebrates live worms or shrimp. After awhile you may get him to try frozen foods and then maybe pellet foods. If you can get him over to prepared foods then keeping him will become much easier. If you can't then live and or frozen foods may make him difficult to keep.-Chuck>

FW algae and Apteronotus skin Hi, In my 29 gallon tank there are re-brownish specs on everything. My water parameters are fine and I do weekly water changes and cleaning. what do you think it is? <Almost undoubtedly algal colonies... take a read on WWM re> Also I have a Black Ghost Knife for about 10 months now and since November he has shown a weird green/brown gel-like coating over him. I thought it was Ick but wouldn't have died by now if that was the case. Do you know what it is and how to treat it? thanks. <This is probably the animals skin itself... and your good vision. The species is "quite slimy" in good health. Bob Fenner>

FW algae and Apteronotus skin, II Bob, than you for the response I just wanted to add that my knifefish's slime is a little whitish-gray when the aquarium light is on, does that make a difference? <Actually, yes... as stated, you have excellent vision, observation> I mean when I go to the pet shop all the ones are pure jet black. Jahner <These are more stressed... Bob Fenner>

Black ghost knife problems? Hi Robert, I'm a bit worried about my new BGK (my new favourite fish!). I am currently setting up a new tank after becoming addicted to my boyfriend's set up! New tank is 80 litres, planted and has a fine gravel substrate. It is currently stocked with 2 Pearl Gourami, 2 Angels, 3 Tiger Danios, 2 Corydoras sterbai and a small (2.5 inch) BGK. <This IS small!> Tank is two weeks into its first cycle. <Yikes... Knifefishes don't "like" new systems... Hard on them to go through their initial chemical, biological changes> The BGK has been in for 3 days and while it seemed happy in the first two (hiding amongst plants) but I have come home from work today and it doesn't seem right. It is sort of hovering around the bottom of the tank, moving around almost like a drunk person. It kind of wobbles around a bit, then rests and then wobbles around again. It has plants to hide in, as mentioned, and also a piece of driftwood to go under but it doesn't seem interested in this. <Mmm, well, this is pretty standard behavior for the species... but... do you have another, older system you can/could move it to?> At the LFS it was happy hiding amongst Java Moss and seemed unconcerned with the lit tank (I'd watched it there for a couple of days and it seemed very strong and healthy). There are really no other signs/symptoms except this apparent listlessness and my gut instinct (and it appears to be easily caught in the relatively light current and moved along which wasn't happening yesterday). I checked the water parameters and everything was fine - Ph 7.0, temp 26C. Nitrite was very slightly elevated but not of note (I have added Amtrite down to fix this.) <Mmm, only temporarily and at a "cost"... as stated, Apteronotus don't like "going" through cycles> Is it just acclimatizing or do I have a problem?? <Perhaps both> Please help, I was really impressed with what I've seen on the site and decided you're the man to ask! Thanks. Alia <Best to move the specimen to an established, similarly peaceful setting, second best to be very careful of not feeding much, urging your completion of biological filtration (Please see here: http://www.wetwebmedia.com/FWSubWebIndex/fwestcycling.htm.  Bob Fenner>

Black ghost knife fish I have a BGK fish and yesterday noticed three splits in the fin under his body, today there must be about thirty of these splits, could you help me in finding out what this is and what I can do. Yesterday I bought a new African Knifefish and wondered if this may be the cause, I'm not sure because the splits were already there  before I added the new fish. Thank you Anita <These two may well be fighting... during the night probably... I would separate them... the Black Ghost will heal on its own otherwise. Bob Fenner>

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