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FAQs on Knifefish Compatibility

Related Articles: Knifefishes, GymnarchusBlack Ghost Knife, Electrogenic Fishes,

Related FAQs: BGK Compatibility, Knifefishes 1, Knifefishes 2, Knifefish Identification, Knifefish Behavior, Knifefish Selection, Knifefish Systems, Knifefish Feeding, Knifefish Disease, Knifefish Reproduction, Electrogenic Fishes,


Mixing FW electrogenic fishes   7/12/08 Hi! ??? I have a 46 gallon, bowed front tank which is planted and contains many hidey-holes (small and large). About a month ago I purchased my first elephant nose fish and his roommate of one year, a single black knife fish (I love both fish and didn't want to separate them after so long together). <Mmm, problematical... electrogenic fishes often don't "mesh" signal, personality wise> They seem to be great "friends", first sharing the same clear tube and then moving to the same cave. I've read many places that since they are both weak electrogenic fish, they may stress each other. I don't know if I'm hurting them by keeping them together or if they are just not of the norm and actually are good together. <Mmm, well... if yours are getting along... a reminder to all: the "price" of freedom? A: Constant vigilance... a good spiel for these personal-liberty-stolen times> Another quick question, I was interested in getting more elephant nose fish. I heard more then 3, but I'm not sure if a 46 gallon will comfortably house 4 elephant nose. I heard both, that it is big enough and that it is NOT big enough and? I was looking for a reliable answer. Please help! And thank you in advance! ~Rachel <I would not mix more in here... Please have a cautionary, informational read here: http://wetwebmedia.com/FWSubWebIndex/mormyrids.htm and the linked files in order, above. Bob Fenner>

Knife Fan Challenge, comp.  12/19/07 Thank you for your help in setting up our tanks (5, 48 and 75 gallons.) Due to Mr. Fenner's enthusiasm, I am now a Knife fish fan. I am now wanting to set up our final and largest, but before I did that, I wanted to double-check that I'm not headed for disaster. And as a side comment, it is frustrating with so much information on the web there are often conflicting opinions. For example, I thought my African Brown Knives (not Asian) would not be compatible in a pair, but after 6 months they co-existed peacefully, alongside one Black Ghost Knife who is now the same size as them at 8 inches! After finding a photo on the internet of a man holding a baby Black Ghost Knife in his hand that was born in his tank, I want to see if my Knives will breed as well, or at least, co-exist peacefully. I know this is an unusual undertaking, that is why I wanted to check with you, the supreme experts, first. If I were to get a tank of 125 gallons, then 3 African Brown Knives (24 inches of fish) with 3 Black Ghost Knives (45 inches total) would be 69 inches of fish (using the old rubric of one inch per gallon.) I also have had one Bala with the knives who has been happy and health and is now 9 inches (will get 12 I read.) I have also had 2 rubber-nose dwarf Plecos, 2 pictus Pim catfish and a Featherfin catfish, apple mystery snails and a three-striped Corydoras. Will or can these peacefully co-exist as the ghost knife fish become larger? <In this size system, likely so> So far all have been fine on a blood worm diet, weekly 50% water changes and vacuuming and testing the water weekly. The three knife fish have done well, but after I add the three more, and as the Black Knife fish grow larger, can I expect them (or the Bala) to eat the dwarf Plecos, pictus, the Corydoras or the snails? <No. They should be fine together> Then, if I may also ask, for the 75 gallons now that the tank is ready with perfect water conditions, do you approve of our adoption plan: Glass Fish, three-striped Corydoras, Round Glass Fish, Clown Plecos (4 inch dwarves), rubber-mouthed dwarf Plecos, one male Beta, guppies, silver hatchetfish (2.5 inches) or marble hatchetfish (1.5 inches) and either a Featherfin catfish or Bugeye Synodontis catfish. How does it sound? <This mix for your 75 should work... I would go with the smaller Synodontis species. Bob Fenner>

Mixing Apteronotids and Notopterids, Dempsey color, UGs...  9/10/07 ok a couple questions... <The beginning of sentences are capitalized...> could I house a black ghost knife and a clown knife together? <Not a good idea> my blue Dempsey is about 2 inches long , but he hasn't become blue yet. a little in the head and tail but not solid. rest of his body is just white. water quality is great so is there something wrong with him or does the color just come in time? <Likely> what's your opinion on undergravel filtration? <Tried and true. Can work in many applications. RMF> thank you.

Knifefish and Cichlids 8/28/07 I was wondering, I was interested in putting an African brown knife fish in a tank with my cichlids or maybe a black ghost knife . Can this be done?? < You didn't say what kind of cichlids. Usually cichlids are very territorial and will dominant other fish in the tank. Without more info on what kind of cichlids you have then I really cannot recommend Knifefish with your cichlids.-Chuck> -curious-

Black Ghost Knife fish pairs?  8/13/07 I just discovered your website, and it is wonderful!! I've found so much info on BGKs! It has been very helpful. <Ah, good> I do have a quick question. My husband and I bought a BGK about a month ago (Oscar), and he's been doing great! I had read in a fish forum about getting more than one. Several people claimed they had a pair, and they got along great and seemed to enjoy having another "friend" like them around. <Mmm, the exception actually... most Apteronotids fight in small confines> So, today we bought another BGK (Fritz). Though Oscar hasn't actually damaged Fritz or harmed him in any way, his behavior has been aggressive towards him. (Periodically, Oscar darts at him and chases him for short distances.) Fritz respects Oscars space and goes the other direction, but he doesn't seem to be overly concerned with Oscars behavior; he doesn't hide from him (he's been busy exploring his new home); and he doesn't return the aggressive behavior. He simply starts swimming the other way, and generally Oscar doesn't pursue him for long. My question is Oscar, our veteran, eventually get used to Fritz (newcomer), or do we need to separate them now before any real damage occurs/their own health and happiness? <I see the pertinent info below> Oh, they live in a 29 gallon (long) tank for now. <This is too small a world for these two> Oscar is a little bigger than Fritz (approx. 3-4"); Fritz is the same size Oscar was when we bought him a month or so ago. We are cycling a 55 gallon tank before we add any fish. <Good> Both of them have eaten well since Fritz arrived. Fritz acts totally normal besides being a little more active than usual, which I'm guessing is due to his new home. It's Oscar that all freaked out. Thank you!!! Kim <I would move one of the Knives to the new tank once it's ready... and maybe try re-acquainting them there in time. Cheers, Bob Fenner>

Black Ghost Knife w/ Rainbow Shark? <& Banded Pencil?>  - 05/01/07 Good afternoon! <Christina> I apologize if you have answered this question before but I have looked through numerous Internet sites including reading most of your FAQs on BGK compatibility without finding much of an answer for my specific concern. Let me start off by saying that I fully realize that within a couple of years, I will need to purchase a MUCH larger set up and am already planning for it, I just do not have the floors to handle it at this time. For now, I have recently set up a 30 gallon aquarium, have let it cycle, and purchased 2 "diamond" tetras, one honey dwarf Gourami, and a 4-5" BGK. My hopes/plan was to incorporate my 10 gallon fish that have a great need for a larger tank (one 4" angelfish, one 4" Banded Leporinus and one 4" Rainbow Shark). <Yikes... this Pencilfish species can be very "nippy"... the FW minnow shark possibly as well> I started with placing the Rainbow Shark into the 30 gallon that for the past 24 hours has housed the Gourami, tetras and the BGK. The shark immediately went into the large ship ornament that housed the ghost Knifefish. <A typical behaviour... hiding> Both fish started swimming around one another nipping. I removed the shark and placed him back in the 10 gallon until I am able to get advice on the situation. <Maybe another such "ship" or tube...> There are two other ornaments including a tube in the tank that the fish can swim into to hide. Will the Black Ghost Knifefish and the Rainbow Shark be OK together (even in a MUCH larger tank such as 75 gallons or 125 gallons? <Likely so, yes> Is there a better way to introduce them? Should I first place the angel and Leporinus in the 30 gallon? <I would not place the Leporinus here> Thanks for any advice you can provide. ~Christina <There is a good chance that the Shark may get along if introduced slowly (as in a floating colander for a few days, the lights off), but not the large pencil. Bob Fenner>

BGK Compatibility  4/5/07 Hi Bob, <Neil> I just purchased a Black Ghost Knife for my new 240 litre (64 gallon) tank. I haven't set the tank up yet, the BGK is in a 20 gallon quarantine tank at the mo (he's only small - about 4 inches) whilst I cycle the 240. What I want to know is how long do you think I should leave it before putting him in the new tank? <Mmm, till the new tank/system is thoroughly cycled... Not likely much cause/need to quarantine this Apteronotid...> I plan to use half my old used filter and some gravel to hurry the process along. <Good> Also I was thinking of adding 2-4 Angels as well and maybe a few BN plec's to keep algae under control. Do you think I have reached my maximum stocking level already? <Mmm, no... nor "interest level" in my estimation... I would like to add something with a bit more color, movement here... Perhaps some Bleeding Heart Tetras or other characins of their genus, Gastropelecids...> The angels and BN Plec's are not a definite so is there any other fish I could keep with the BGK that would live happily together and not run the risk of being dinner? Thanks Neil <All sorts... Maybe take a scan on fishbase.org re the Amazon fishes... read re the size, temperament of the species they list as used for aquariums... Cross-reference with books, the Net... Bob Fenner>

African Brown Knifefish. Electrogenic fishes, comp.    1/30/07 Hi! About 2 years ago I purchased an African Brown Knifefish <... is this an Apteronotus species? S. American? Or Xenomystus? Or?> and an Elephantnose fish (Fishie and Ellie, respectively). 3 months ago I had to go out of town, so my sister took care of my fish for me. Kind of. <Oh oh> When I got back I discovered the water quality was awful. I managed to fix the water, but Ellie still passed away. I want to get another elephant nose but I've since read that these 2 types of fish tend to hate each other. Is this true? <Mmm... depends on what species the former is... but in general, a qualified yes here... Electrogenic species of fishes are best not mixed in small volumes/aquariums> These two always would play together and even slept in the same little pot, despite have numerous places to sleep separately. Should I scratch the Elephantnose plan and just get a different type of fish? <Mmm, up to you... but I would be prepared to move the newcomer if there was obvious agonistic behavior> I'd be devastated if anything happened to Fishie. The tank is 55 gallons and is being upgraded to 95 in June, if this makes a difference. <Does... the larger the "world" the more likely they... and other species will get along> Thanks so much, Amanda <Thank you for sharing. Bob Fenner>

FW mix: ghost knife, barbs and red-tail shark   12/9/06 Hello! <<Greetings! Tom here.>> It's been such a blessing to have a website like WetWebMedia to hobbyists like me. Thank you very much! Thank you in advance for your reply as well. The crew has been really helpful. <<Youre quite welcome and thank you for being so complimentary.>> I am just wondering, is it possible to keep 3 tiger barbs (2"), a red-tail shark(2.5") and a black ghost knife(3") in a 15 gallon aquarium? (Since the black ghost knife would not grow that fast I want to keep it there first.) <<Not in my opinion. First, I wouldnt want to make the assumption that a given fish will be slow-growing. Theres been evidence to the contrary about the rate of growth of the Black Ghost Knifefish. Second, the tankmates youre suggesting might find the Black Ghost pretty tempting to nip at, particularly the Barbs. Third, there may just be enough similarity, early on, between the Red-Tail Shark and the Knifefish to cause problems behaviorally. These Sharks are quite intolerant of their own kind as well as other species that resemble them. Finally, unless youre prepared to ultimately house the Knifefish in a tank thats, minimally, 90-gallons or greater, I wouldnt consider this animal. Fascinating as these creatures are, they need room, room and more room in order to thrive. As you may already be aware, you can expect a healthy individual, in appropriate conditions, to grow to as long as 20 inches. Thats a lot of fish!>> Will they be good tank mates? <<See above>> Other references say that it is possible to keep them together but the pet shop said otherwise. I do not know what to believe. <<Believe the folks you spoke with at the pet shop.>> Can I still add one red-tail shark and one more tiger barb with my 5 fishes already inside? <<A second Red-Tail Shark would be a recipe for disaster if only between themselves. Stick with only one per tank. A fourth Barb would not be a problem but, again, this presupposes that the Knifefish is not part of the scheme. Im sure many of our readers feel that we belabor the issue of tank size but its with very good reason. I dont advocate mixing species that are known to be questionably compatible but in a large enough environment, youd have a chance. In a small environment, thered be little or none. Our first responsibility must be for the lives we take into our charge.>> Again, thank you very much for your help!!! ja Lukban manila <<I fear that Ive been a bit of a wet blanket but I commend you for asking before acting. I think its a good bet that youll have your Knifefish when youre properly prepared for it. My best to you. Tom>>

BGK, crayfish, and bumblebee catfish Nocturnal Animals Need More Places To Hide  9/8/06 These three fish are not getting along very well. I think that the crayfish just wants to be left alone but the bumblebee and the Black Ghost Knife keep fighting over a cave and run into the crayfish. My tank is 55 gallons but I think I just need more hiding places is this correct? < More hiding places will be just fine.-Chuck> <<... NO! Separate these fishes from the Crayfish. Chuck! RMF>>

Re: Black Ghost Knife With Diseased Tail   9/11/06 Hello again, I spoke to you last week about my BGK now it looks at his tail is rotting away and has some fuzzy stuff on it. Will the Melafix help that as   well?  I don't want to lose him. Thanks for all your help. Kelli < Do a 50% water change, vacuum the gravel and clean the filter. Treat with Nitrofurazone. The tail will not grow back but the disease can be cured if treated quickly.-Chuck>

Black Ghost Knife Missing Tail  - 09/14/06 Another question is I think that the crayfish got ticked and bit the tail off of the ghost knife up to the white part will it grow back? < Probably not. If is does it is usually not as long or as nice as the original.-Chuck> <<Separate these animals! RMF>>

Mixing Apteronotids and Mormyrids... not advised   6/3/06 Hello,       I recently sent an email to you guys in relation to keeping a freshwater dolphin in a 70 gallon planted discus aquarium. I received a reply of yes but forgot to add that I have a 15cm black ghost knife. I am aware that the ghost has a form of electrical field and was wondering if his and the freshwater dolphin will fight???? <Too likely, yes> I would also like any opinions on whether its possible to house 2 black ghost knives together? I would buy 2 smaller ones of the same size and house them in a large tank with plenty of logs and hiding places) Have you ever heard of anyone doing this successfully? <Yes... in very large systems of consistent low pH, alkalinity...> I just love this fish so much that I would have 20 of them if I could!!!!!  One more thing, how long will it take my black ghost to reach adult length. <A few years> thank for your time! Jarryd <Bob Fenner>

Mixing mildly electrogenic fishes... BGK and Mormyrids together?   5/27/06 <<Tom>> I was wondering if its possible to house a black ghost knife fish with a baby whale? My mum fell in love with one at our LFS. The tank is a 70 gallon planted discus with two canister filters going strong, and regular partial water changes. <<First of all, I'm assuming we're speaking of the Knifefish here. Very cool fish! To answer your question, this shouldn't be a problem as long as you have hiding places available. Your tank is certainly of sufficient size to very comfortably house this animal and I highly doubt there will be any serious territorial disputes going on. I hope you and your Mum enjoy your new pet, Jarryd!>> Thanks for your time, Jarryd <<You're most welcome. Tom>>

Black Ghost Knife Fish - Needs Help, diff. tankmates    4/18/06 Hi there, and thank you for your time. Just a quick question, though it may be an obvious answer. I've had my Knifefish for about 2 months now ( my third attempt) and it was doing well. I have tetras, a pictus cat fish and some Kribs. They were all fine together until recently when I noticed that my Knifefish tail was completely bitten off!! <Could be from...> There is now what appears to just be his bone. I noticed the other fish nipping at it ( though I believe it was the work of the Kribs to begin with) <Most likely> so I have isolated him in the tank with some food and shelter so that the others wont keep eating him. He doesn't look to great at the moment there is a bit of red, but my question is...will it recover? Is it possible for their tails to repair? <Possibly and yes> These are my favourite fish out of the many I have had and I really want to save him. Thanks again for your time, Dee <Do favor this fish with water conditions per the species (see WWM, fishbase.org re) and use Mardel's line... Maracyn, Maroxy. Bob Fenner>

Brown Knifefish, wrong env., tankmates  - 02/27/06 Hello!  I have a quick question regarding my brown ghost Knifefish.  Some background, I have a 29gal tank with a Eclipse 3 hood/filter;  20-25% water changes weekly, with tank salt added each time as well as conditioners. <Don't like salt> (The filter is changed every 3-4weeks);  Livestock:  Bala shark (approx 3yr old, 7in), <Too small a tank for> albino cat (about 4-5in); a blue white striped cat (about 3in); 4 ghost catfish (about 3in each); 1 Pleco (unsure the type-about 2 in); 1 pearl Gourami (3-4in); and the newest arrival (2mo.) a 4 in brown ghost knife- Charlie Brown; Ok, here's the problem.  I have provided plenty of cover for the BGK with (silk) plants and a 6in clear glass hurricane piece for cover/protection (which is completely ignored by him!) as well as a castle figure.  My question is regarding his health and behavior.  Charlie Brown (and the crew) is fed a mix of frz. blood worms or community mix (of krill, shrimp, etc) 1x/day, although I do not actually witness him eating very much at all. He spends most of the day (vertical) in the light  b/w the bubble wall and driftwood that is situated along the back. He has recently developed red spots in the gill area, and has lost some coloration. Can you please tell me if he is ill and is his behavior normal? <Is ill... poor tankmate choices (can't compete), likes different water than much of what you list... and the salt...>   And what, if anything, would need to be done?  Thanks! Rachel S. <Place this animal in an appropriate environment. Read re this per species on WWM, fishbase.org. Bob Fenner>

Brown Knifefish/African Knifefish ... comp., systems   2/3/06 We just recently purchased a brown Knifefish from the local PetSmart.  It is about 5 inches long and seemed to be doing fine.. at first.  After 2 weeks he has developed a coating in his skin, looks like dead skin or dust. <Bad...> We are very concerned and I read on your website about the parasitic disease that can be caused by ammonia and nitrate levels. <Yes... or just "unsuitable water quality" in general. Touchy fishes (S. American) knives... that like very stable, "clean", soft, acidic water of high temperature... and live foods, no rambunctious tankmates, subdued lighting... Wish the mass-merchandisers like PetSmart would leave off with such touchy animals> That sounded like what he has.  So, my question is- will fixing the ammonia levels and nitrate levels, doing a 30% water change with conditioner and vacuuming the gravel, fix the problem? <Possibly... hard to be very confident here... as if these fishes "go too far" they are very quickly lost... if assured as to real/root problems... or not, I might go with the addition of a Furan compound (Nitrofuranace) as well>   The fish is in a 55 gallon tank with lots of hiding places and the other fish leave it alone.   Thanks for your help!   Casey <Mmm, not really a "community fish" per se... I do hope yours recovers. Bob Fenner>

Black Ghost With Discus  12/5/05 Hi there. Just wondering , I'm thinking of setting up a discus tank but have a ghost knife that I love to death. My question is would the pH, water qualities of discus affect my ghost knife ???? < The water parameters for both are about the same.> More importantly would the discus co-exist peacefully with my ghostie?  Thanks for your time.  Jarryd < While the black ghost is small they would probably get along for awhile. In fact you probably would not see the black ghost during the day with other fish in the tank. But you ghost will get pretty big over time . Maybe up to 18 inches plus. At it grows up to this this size it will harass any other fish with its electrical field and would probably do best in its own tank. Chuck> 

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 serape 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>

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 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>

Black Ghost Knife, yellow water, killing fishes I have a couple questions for you, I hope you take time in answering mine. I  see you do take a lot of care in the questions people ask. Here's one; I am wanting to buy a black ghost knife fish. Is this fish territorial? I  already have a loach in here and I don't want them to fight. <Likely will get along> Plus we don't want to buy pellets or freeze dried food, so will it survive on flakes? <No> My loach has been surviving for a couple months without those foods. <Won't be healthy on nothing but flakes forever> My second question is, my tank is getting yellowish color really fast and we clean our tank (55 gallon) like once every 2 months. What is up with that? <Need to do more frequent, partial water changes, maybe weekly... and possibly use carbon in your filter flow path> My final question is, my fish seem to be swelling up really badly, and then just die. I put in some medicine.  Is this what you call ich, if so what is it and how do I stop it? Thank you. <... time to study... and adapt a better maintenance schedule... It sounds like your system needs more regular care... likely your fish deaths are due to poor husbandry, a lack of nutrition, perhaps mis-medicating. Take a read over our website: http://www.wetwebmedia.com/FWSubWebIndex/fwsubwebindex.htm re Set-Up, Knifefishes, Maintenance... IF you want to be successful at keeping an aquarium you need to learn more re what it takes to care for it. Bob Fenner> 

Mainly Black Ghost Knife questions Hi and thank you WetWeb staff, My fish are doing great, after a very scary introduction. No one died and having been doing great (refer to suddenly stocked tank on WetWeb).  Well just a few questions, if I may.  But for reference I have a 55gal with Emperor 400, heater, etc., lots of (fake) plants, semi- fine (1/8" or smaller) substrate, a few rocks of different shapes making caves, heated to 80F, 7.8 PH, all levels great. a 8" BGK <Black Ghost Knife> a Pleco 6" 2- Blue Gourami (or Opaline Gourami not to sure because they have changed colors since I got the new one) a 4" and 2". a tiger barb 1.5" a clown loach 1.5"(just got him) a zebra loach 1.5" a ????? frog .75" I feed my fish a very wide variety of foods on a change by day basis.  My BGK has always been black and yellow I researched why because what I had seen was they should be white, I think on your site I was reading that some BGK are of a yellow variation. <Yes. this is so> Well my question is since I got mine a month and a half ago, he has started to turn whitish starting at the bands on his tail? I don't know why, I know that where he came from he was poorly fed and in a bad environment. Well Are there yellow variations or not (just mistreated BGK)? <The white/yellow markings do change with diet, water quality> My next question(s) is.  I now have 2 blue gouramis how long will it be before they will reach sexual maturity?, <A few months> I know they're bubble nest builders but have never seen them do this. I have lots of plants. is it a comfort level or something? <In part... also, the motion in the waters surface, the presence of other fishes> they seem to be very happy, the most aggressive feeders in my tank (other than the BGK at night). what I'm getting at is if they will\can breed? <Doubtful, unless given a calm, warm setting... on their own> I cant find anything on sexing them so I don't know. <Search the Net, books... not hard to discern if of size, maturity> and at the same time can my loaches possibly breed? <Can, but rare... they do get BIG (a foot or so)...> They are inseparable.  I would also like to get 1 or 2 Bala sharks (I am going to be getting a new 125gal in September and plan a move) will they get along with what is in my tank? What else is a possibility for moving fish? Thank you all for the site and personal help, James <Yes, and many choices. Bob Fenner>

BGK tank mates Hello, I have a Black Ghost Knife that I've had for about 5 months, about 4 inches.  He shares a 60 gal. tank with my Pleco and 2 Platy's.  I have a Fluval 404 for filtration and maintain the water regularly.  I'd like to get bigger, livelier, compatible fish for the Pleco and BGK.  I have a feeling the Platy's will eventually be food for a larger fish.  I'd love to get an Arowana but think it will outgrow the tank too soon and eat my BGK.  What about Oscars, Eels, Catfish, Red Tail Sharks?  I had a clown loach before but it was very spastic and swam anxiously in circles and eventually died.  What fish and how many can I add to my tank that would be best fit for the BGK and Pleco?   Thank you. Kristen <Hello Kristen, I'm afraid for what you want to keep in your 60 will certainly exceed the capacity of the tank when the fish get larger.  Keep your BGK and your Pleco and maybe add a red tail shark.  James (Salty Dog)>

Re: BGK tank mates Thank you James.  If I only add the red tail shark, is that enough for a tank of this size?  I've heard that I should be keeping 9 fish in my tank at all times for natural bacterial purposes.  Are there any other fish you would also recommend? Thanks again. <Kristen, Both the black knife and the Pleco will grow quite large so I am basing that on future growth of the fish unless you plan on getting a larger aquarium in the future.  The main thing is to monitor your ammonia levels.   When you add a new fish, check these levels for a week or two to make sure the biological system can handle the extra load.  James (Salty Dog)>

Ghosts, Knives and something else I have a 55Gal tank with only an 8in. Black ghost <max over 12"> and a 7in. African black knife <max 8 to 12">. I am trying to find what other fish I can put in the tank and how many of each would be appropriate. I used to have a Silver Arowana but he got way too big for the tank (27in) so I had to find him a new home. And my albino clown that I loved died after I took the Arowana out. I have tried Nicaraguense, Bala sharks and a Green Terror but the cichlids seem to pick on the black ghost and the Balas are so twitchy.  I am thinking about trying another clown but it would be nice to have some fish they weren't always hiding. The tank is pretty lonely and I don't know who would be most compatible with the ghost. I don't want him to become fish food <Nothing that will fit in a 55 will take an 8" ghost> or make fish food out of them <Very likely, unless too large to fit in it's mouth>. Nicole. <The biggest problem I see is the size of your tank. A 55 is fine for what you have now. But you would have to add some fairly large fish to ensure they do not become a late night snack. And if you want a few of them, the 55 shrinks in my eyes. Clown loaches come to mind. They grow large, but slowly. Some of the larger Cory species would also be safe. Don>

Knives, Spines, Rope and Fire. OK to add Claws? Hi, thanks for the info that you've given me so far, but I've got another question. I've got my 130 gallon tank set-up with a 10" clown Knifefish, 12" spiny eel, 6" fire eel, and 12" Ropefish.
<No guppies or swordtails for you, huh?>
 I also own two African clawed frogs (about 4" long each) that are being kept at my mothers work. I'm wondering if I would be able to put the two frogs in the 130 gallon tank. In your opinion, do you think that the clown might decide to take a bite out of the soft, fleshy frogs, or would he leave them alone? Right now, the clown eats 3" long goldfish, but I'm trying to get him to accept frozen shrimp.
<A bit risky, IMO. A Knife will eat anything he can fit in it's mouth. Even if he only tries, he may kill or injure the frog. Not a great mix. Risk would be reduced if the Knife was off live food first and kept well fed. The eels may even cause problems at night, but less likely.>     Also, one other question.  For my 130 gallon tank, would a Classic Eheim 2215 canister filter and a Fluval 404 canister filter be enough for the tank? I'm going to be adding more fish to the tank than I have now and prefer to have above average filtration. If the filtration isn't enough, what's a good filter that I could add to the other two? <Each are rated for around 100 gallons. You should be fine as is, but those are some pretty large fish in there, and growing. I'm a big fan of Marineland's Emperor 400 for bio filtration. Surely wouldn't hurt to add the bio wheels to help with ammonia processing.> Thanks for all of your help. <One last point, which I'm sure you knew was coming. Try very hard to get the Knife off live fish. Hard to do, I know. But unless you can QT the feeders, sooner or later you WILL (not "may") bring Ick or some other nasty into your system. Treating a 130 with these large fish will be a challenge to say the least. Don>

Black Ghost Knife Help Hi there from another fishaholic!
<Hi Jennifer, MikeD here>
 Sorry to bother you with petty questions that really don't apply to any of your other visitors, but I *really* need some help regarding my black ghost knife.
<One of my all time favorite FW fish>
 Although I generally research fish species very thoroughly before purchasing them, I only did a little such research before buying a black ghost knife. It was really pretty much an impulse buy, though I was at least somewhat familiar with the species.<They're pretty tough if handled right> At any rate, the manager of my LFS promised me that if I purchased one, he would do just fine in a twenty-gallon, provided he had plenty of coverage and was kept completely by himself. She did say that it was pushing the limits to keep him in a 20-gallon, but that he'd do okay, even as an adult. (He's 7 inches now.)<I'm not sure why they told you to keep it alone, as they do well with many other species if the tank is arranged correctly. As to the adult part, my largest grew to about 15" if that tells you anything> Now, I'm starting to have second thoughts on that. I assume he's okay for *now* in the 20-gallon, but will he really be okay when he grows up? I have an extra 35-gallon that I haven't stocked yet but it's very well planted and decorated, as I tend to pride myself on that. The problem is, it's very hard, brackish water, and it would be a huge inconvenience to redesign and refill the whole thing. Besides, I was really looking forward to the archers and Sailfin mollies I was going to keep... But, if I need to, I'm willing to change conditions if that's what it takes to save my ghost knife. (I simply can't afford another large aquarium for him.)<OK. While he WILL eventually outgrow the 20 (20L or 20H?), they are fairly slow growers so you've got at least a couple of years before it should become a concern.> Wow, you're very patient if you're still reading this.
<Still here **grin**>
 I guess, to get to my point, can my ghost knife stay in that 20-gallon as an adult, or even now? Or will I have to completely revamp the 35-gallon for him? Would a 35-gallon even be enough? Should I just swallow my pride and give that poor fish to somebody that can take better care of him? Just how fast will he grow, anyway? Maybe slow enough that he could stay in the 20-gallon until I could afford a new tank?<I guess I should have waited until I got here to answer, eh? **grin**> Also, the LFS lady told me that black ghost knives can be held and are even intelligent enough to recognize their handlers... is this true? Sounds a little odd...<It depends on what she means by held. If you cup your fingers in the water, they will indeed swim into your hand if you train them.  I don't know what you're currently feeding it, but they also appreciate meaty foods, with their favorite being earthworms. They'll also appreciate ghost shrimp and even a piece of raw shrimp like you'd have for dinner, unbattered, of course.  These are small cousins of the electric eel, and I'm assuming you know that they navigate by true electronic sonar. Because of this, never add another S. American Knifefish or African Mormyrids, such as "baby whales" or "Elephantnoses"...they cross each others electric signals and a true war will result> Thank you SOOOOO much for your help! <You're very welcome>

Off-colored Ghost Knife and Oscars with Angels - 02/22/2004 Magnus... <Sabrina, today, hope all is well> Thought I would update you on my ghost who lost his color. I put him in my 5gal guppies tank.  Thought that would be best - no one to intimidate him.  Of course, he loved the old car for his home, and as expected, the baby guppies all disappeared.  Had to make a decision of sacrifice to hopefully keep him alive.  I noticed a bit of black coming back (due to fresh "sea food" I'm sure...), <And you'll surely have more baby guppies in the future, no worries.  Good that they have contributed to your ghost's well-being, a worthy cause, IMO.> but he has outgrown the little tank, <Heh, to be expected!> so I moved him to the 38gal.  This tank consists of Parrots, Tiger Barbs, and a handful of misc.  The red tail shark is probably the most aggressive, but lives in harmony with the others usually.  Once in awhile he'll chase the barbs around.  So far the ghost has found an ornament to hide in and seems to being doing okay. <IMO, all of these are too aggressive as tank mates - do keep an eye on him, watch closely for splits in his fins or any other signs of distress.> Another question....I have a 60gal octagon with two Oscars, two tins, <Hmm?  Ahh, tinfoil barbs, yes?> two fire mouth cichlids and two angels and a silver dollar.  All is well with the combination at this point, but as the Oscars grow (one is about 6"), do you think the angels will be okay?   <Not at all, not in this size/shape tank - I would consider all tankmates grossly at risk of harassing/harming one another as they "grow up" - the Oscars will likely require a tank of their own, if they're getting on well, they've likely paired.  Removing them to their own space will give you some wiggle room for the rest, and the Tinfoils are the next biggest worry - topping out at about fourteen inches.  Fortunately, they are durable, and slow growers - I would remove them with the Oscars.  A tank that is big on surface area (er, not a hex/octagon/tall tank) will do best for the four.> One angel is quite large, the other only about 2 1/2 inches.  I know there is not always a rule to go by, but do you think I should move the angels? <The Oscars and Tinfoils will need a larger tank in the long run.... not so much larger in gallonage as in usable space.> FYI-my "herd" has gone down in numbers.  I have been very blessed to have had 6 adoptions in the past two weeks.   <Wonderful!!> Down to 13 dogs-seems so quiet.   <Sounds like you're doing quite well.> Thumbs up to your girlfriend for helping the shelters and rescues-wish she was here! Have a wonderful day.  Ren <You, too.  Wishing you well,  -Sabrina>

Ghost knife with cichlids My son has had a black ghost knife fish for four years. He is about 9 inches.  We, being ignorant, were keeping him in a <gasp> 10 gal. aquarium all this time. <yikes that is a bit small...> The last few months he ("Sonar") would stay out of his ghost tube most of the time and do loops a lot.  We increased his feed. <that happens with Knifefish small tanks seem to have them get restless.> Anyway, at Christmas I bought him a 29 gal. tank <wow> thinking that would be wonderful.  It came with an Aqua-tech 20-40 power filter. <I know you're laughing>.   <Any filter is better than none, just have to make sure the water parameters are okay.> Being ignorant again, in regards to the new tank cycling.  I also bought two convict cichlids to keep him company.  My thinking was they could hold their own with him since he killed the Neons and Bala shark my son used to have.   <be cautious with any cichlids and Knifefish, cichlids are nippy things, and if a Knifefish should loose his anal fin (which is it's only real propulsion) then it is done for.  I try to keep my Knifefish with tankmates that I know won't bother it.> I used the Stress-coat and Stress-zyme.  The ammonia levels got really high.   <A fish that size is bound to put out some high amounts of waste and ammonia> I did have a knowledgeable man at Petco advise me on changing out the water and doubling up on the stress-zyme.  So I did that two times the first week, about 25%. <The stress-zyme isn't really helping the ammonia levels, it's helping the water additives in your water.  The water change is helping the ammonia levels. So keep up on the water changes.> I kept asking about using our filtered drinking water  at fish stores and no one seemed too concerned.  We have rural chlorinated hard water but a water softener, which is what I used for the tank.  I now plan on using the filtered for the next change out. <many Saltwater people prefer using filtered water for their tanks, nothing saying you can't use it.  Just that it can get expensive.> Should I still use the chemical additives? <It's not hurting the fish any, so you can keep doing it, just only add what is recommended on the package.   Good luck with the knife.  When they get older you will have lots of fun.  I have a friend that feeds his ghost by hand.> My main question is should I get rid of the two cichlids?   <I would, they run the risk of damaging the knife.> Since all this I have spent a lot of time reading and learning ( a good thing) about these guys. <That is a very good thing.  Research research research!  you will have more fun if you know what to expect.>   I think they are both males.  The bigger one (they're both about 3 in) chases the other a lot and so he hides by Sonar which is sometimes in his tube with him.  I just noticed a couple slits in Sonar's ventral fin now and I'm feeling very guilty.  Other than that they seem to not bother him.  He still does his loops and does come out to feed when the light is on although he is spending more time in his tube again. Also, I have learned we really didn't have a biological filter so I stuck a trickle filter sponge in the power filter where the water flow out hoping that will help. <any more filtration is better than what is on there.> I'm pretty sure I'm going to find a home for these cichlids even though I enjoy watching them.  I thought of just getting rid of the aggressive one.   <You can set up another tank for them.  Cichlid tanks are extremely rewarding.  Get a male/female pair, and within 3-4 years you will no doubt be an expert and breeding them for you LFS!> Sonar is my biggest concern.  Should I do anything else?  Any suggestions you have would be greatly appreciated. <I would separate the fish, chances are high that they will pick at Sonar when you aren't around.  Give some thought into setting up a cichlid tank, I'm sure you and the family will really enjoy them!> Sheryl in Missouri     <good luck Sheryl.  -Magnus in New York>

Large Fish Compatibility I have recently bought a striped shovelnose and a black ghost together and the pet store said they were compatible, which they are. they don't bother each other. later on I bought a gold Severum and 2 clown loaches, which the pet store said that the Severum and clown loaches would go good with the black ghost knife fish and the shovelnose. nothing has happened yet because they are all pretty small. but I was telling someone what I had in my tank and they said that I shouldn't have listened to there advice because the black ghost knife fish would be fish food sooner or later. so I was wondering is that true? I do know that the Severum is compatible with all the other fish but I couldn't find any information on the black ghost fish. if you can help I would much appreciate it.         thank you          sincerely, Lindsey <Hi Lindsey, I am scared to ask what size tank you have.  These are all fish that get really large.  The shovelnose can get close to 2ft, and the Ghost knife will not be too far behind.  In a large enough tank you might be ok, I personally do not trust large catfish with smaller tank mates, they have a tendency to eat them.  You can find more on the Ghost knife at the links below.  Best Regards, Gage http://www.wetwebmedia.com/FWSubWebIndex/knifefishfaqs.htm http://www.mongabay.com/fish/knifefish.htm  >

Black Ghost Fish Hi   <Hello> I   am setting up a tank for a ghost fish and want to know what sort of plants are good for putting in the tank and what other fish are suitable if any <Tropical South American plants are my fave... ones that would, could be found in the same habitat. Tropica has a nice website that shows some of these biotopes... and maybe some sunken driftwood. Many medium sized Characoids (tetra) fishes will go with this Apteronotus... as well as Callichthyid catfishes... even angels. Bob Fenner> Cheers Shelley Molloy

In Love with a Chocolate Ghost Knife Hi Bob, <Hello Susie> I have recently (three weeks ago to be exact) set up a freshwater (20 gallon) tank. My daughter has four aquariums, and has been quite successful with her fish. I went to her "fish place" to purchase a few new fish and fell in love with a chocolate ghost knife. <A beautiful and intelligent species> The owner of the shop assured me he would be fine with my mollies (5), guppies(6), Platies(2), Cory cats(2), red tail shark(1), silver stripe shark(1), leopard algae eater(1),and Neons(4). He is about five inches long and he is beautiful! I would really like to keep him, but now I have read on some internet sites that this may be bad. He seems to be fine, and prefers a rock cave to his clear tube. My questions are : <Well... it will likely eat all baby livebearers... and your Neons in time... And the "sharks" prefer different water quality... hard/alkaline versus softer/acidic... and the worst fact to relate... your tank is way too small for all these fishes.> 1.Did I make an incorrect purchase? 2.Will he kill my other fish? 3.How does he find his food (bloodworms are what the guy suggested). 4.Does he absolutely have to have live food, and if so, what should I give him. <Not live food, frozen defrosted meaty foods will likely do... offered right after "lights out" for the Ghost...> I would really like to keep him, but I do not want to do the wrong thing. <There are many other things to know about this fish and its relatives... they don't tolerate much in the way of standard fish medications... are electrogenic... Bob Fenner> Susie

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