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FAQs on Featherfin/Notopterid Knifefishes

African Knifefish with Elephant Nose... Ost. comp. 01/13/2008
I've read conflicting information in various media concerning putting African Knifefish with Elephant Nose fish.
<Indeed?>
I'm moving my 7" African Knife into his own 55 gal tomorrow and would like to know
if I can put my two 5" Elephant Nose with him.
<Possibly, but Elephantnoses do get a bit territorial, so make sure it has lots of hiding places. Xenomystus nigri isn't one of the Knifefishes that generates an electric field, but it is apparently sensitive to them. So while I doubt the Elephantnose will make a bee-line for the Knifefishes in the same way it does other electrogenic fishes, the Knifefishes might get annoyed by the electric field from the Elephantnose, and that could lead to tensions.>
I know both fish have weak electrical fields.
<Xenomystus nigri does not generate an electric field. Appearances aside, it belongs to the non-electrogenic Notopteridae Knifefishes, a different group to the electrogenic Gymnarchidae and Gymnotiformes, both of which contain true electrogenic species.>
Several sources say you can mix Elephant Nose with African Knifefish but *not to mix them with Black
Ghost Knifefish. A bit confusing because they don't say WHY. Temperament perhaps?
<Black Ghosts -- Apteronotous albifrons -- are members of the electrogenic Gymnotiformes group, and likely when Elephantnoses and Gymnotiformes are mixed, the two varieties of fish annoy each other with their electric fields.>
The 2 Elephant Nose bump into each other but I've not seen any aggressive behavior in the 2 months I've had them, they seem to get along well and were bought together from the same tank.
<In theory, Elephantnoses are schooling fish, but in captivity they often don't get along. The reasons aren't clear for this.>
All 3 fish are great eaters but I'd like to keep them separate from my other fish because I'm afraid they just wouldn't be able to compete for food in other tanks.
<Agreed, though provided Elephantnoses are mixed with species that never take food from the bottom of the tank, they can be placed in communities. Hatchetfish, halfbeaks, Danios, African Butterflies and so on would work.>
Would it be a reasonable solution to put them together? There will also be a 1 1/2" Raphael Catfish but no other fish.
<Certainly worth a shot. I tend to recommend against mixing catfish/loaches and Elephantnoses because of problems with feeding. But if your fish are feeding well already, then maybe you'll be fine.>
Thank you for your time, options & your dedication.
Sincerely,
Mitzi
<No problems, and happy to help. Neale.>

Re: African Knifefish with Elephant Nose 01/14/2008
I'm going to go look (online 1st) for "The Diversity Of Fishes" and snatch up the 1st copy I find, thank you! You can't put a price on a good book that you can refer back to for many years, I love books. It fascinates me that if we give a fish what IT needs (physically, psychologically & diet-wise) that the other aspects fall together.
<Hi Mitzi. Yes indeed... one of the nice things about keeping fish (compared with, say, dogs) is that it's relatively easy to create an environment so natural the fish will complete its entire, natural life cycle in captivity including social interactions, courtship, breeding, and brood care. Dogs, by contrast, are largely limited to being pets, and rarely get to interact fully with other dogs, let alone organise themselves socially.>
Common sense should tell someone Elephantnose don't need any bottom feeding completion. The fish shop told me to put them with Loaches and feed only brine shrimp, I just roll my eyes at
them most the time.
<All too common. Most stores see them as oddball "scavengers", which they're SO NOT!>
These 2 will eat just about anything. I had to get creative but I figured out that if I cut stringy chunks of any kind of meat or insect they'll devour it.
<Try putting in a small ball made of aluminum foil; supposedly Elephantnoses find these "toys" fascinating!>
All my tanks have zucchini or
squash in them and they even mash their funny noses into that. I haven't figured out if they're eating or not yet-but it's sure fun to watch them!
<Not sure if they're eating it, but perhaps. They do hunt mostly by olfaction, and only secondarily using electric field detection. Hence they "touch" interesting things with that chin barbel to taste it.>
It makes me wonder if they can communicate
somehow.
<Yes. Communication in Elephantnoses has been much studied and is known to be extremely complex. Essentially, dominant individuals "monopolise" the best frequency, and lower status individuals have to use less desirable frequencies. Within the group, there's constant jockeying as fish try to use the best frequency (i.e., the one that offers best navigation resolution). Presumably, they also use electric signals to convey things like sex and willingness to mate.>
One will find food and 1/2 a second later the other one will come shooting as fast as he can from the other end of the tank. Just like chickens.
<Hah!>
I can't wait to find that book-thank you so much!
Mitzi
<There's quite a big chapter on electricity in fishes; it is a unique sense that fish have but no other vertebrate (something to remind those annoying "warm, fluffy animal" chauvinists! Enjoy, Neale.>

Re: African Knifefish with Elephant Nose 01/14/2008
Food for thought here. There was much you told me that I honestly didn't know. I don't know where else I'd have found such specific information (which is why I pick your brain often). I wish I had access to some sort of a "fish library" like the medical library we have. I'd be in heaven.
<Hi Mitzi. If there's one book I'd recommend for anyone interested in fish beyond merely keeping them alive in a glass box, that book would be 'The Diversity of Fishes' but Helfman et al. It's a university-level text book, but so well written, and with so many diagrams and photos, that I think anyone with even a mild interest in how fish work and what they do will find it a fascinating read. Not a cheap book (I think I spent about £50 on my copy ten years ago) but should be accessible through libraries or used book stores if you don't want to pony up for the new edition. But trust me, once you've taken a peak, you'll want your own copy... it's that good!>
I did move the African Knifefish & his little Raphael Catfish yesterday as planned but did *not put the 2 Elephant Nose in there, it didn't feel right to do so because the Elephant Nose are such busy bodies.
<Elephantnoses are exceptional fish in many ways, and great fun once you understand their needs. They are among the very few fish for which scientifically accepted "play behaviour" has ever been observed, implying a level of intelligence well above what we normally associate with fish.>
I didn't want Wendell the Knifefish to be stressed with all that activity. After reading what you had to say I'm glad I held off.
<Cool.>
The Elephant Nose have been in a 3 ft tank with 10 Hatchets and I guess they'll stay there until the aquarium fairy brings me a bigger tank for them.
<Sounds as if he's happy. You seem to have figured out that elephantnoses do best with surface-dwellers. Good call.>
Thank you, Neale. You've no idea how much I appreciate you.
<Not a problem.>
Mitzi
<Cheers, Neale.>

Re: African Knifefish with Elephant Nose 01/14/2008
So much I didn't know about the Elephantnose-even after all I thought I'd read.
<Always the way!>
I found the book and ordered it on Amazon.com. I'm so excited :-)) My birthday is Jan 15th so it's a birthday present to myself, I can't wait to get it!
<Hope you will enjoy.>
I actually do understand the interactions of dogs, to a certain extent anyway as mine are all spayed or neutered. Dogs were my "1st love" as far back as I remember. People seldom understand why I 'want' a dozen dogs in the house but then they don't understand my fascination with a dozen aquariums either. I see & understand the interactions between the dogs, I can tell at a glance what each dog is portraying to another, why they're doing it and how to either stop or encourage the behavior.
The dogs know the 'leader' is the short blonde lady with the aquarium hose-ha!
<You "get it" -- Dogs are happier when kept in groups of their own kind, not just with people. At the very least, it's so much nicer for a dog when you take it on walks with someone else's dogs too, so that they can make a little "pack" and go do their thing, instead of always following the Two Legs about.>
Sorry to take up your time, but I learn so much from you and maybe what you write will help someone else with these same kind of fish.
<Who knows!>
Thank you!!
Mitzi
PS I'll try the aluminum foil with the Elephantnoses. It'll give me and the Hatchet fish both something to watch :-)
<Let me know what happens. Have read this, but never seen it. Cheers, Neale.>

African knife fish (Xenomystus nigri) fish/system compatibility question 8/4/07
<Hi Matt, Pufferpunk here>
I have read much of your site (actually just about everything in your freshwater fish section and half of the planted aquarium section) in my leisure time at work and I could not find a definitive answer to my query.

I currently have a 120 gallon tank with seven 4-5" silver dollars, an 18" common Pleco and 6-8 Cory catfish (plus about 200 plus snails of various species). The tank is well established, (ammonia 0, nitrites 0, nitrates... too high, I wont be getting the knifefish unless I can controllably get my nitrates to under 20ppm) has a variety of floating plants such as anacharis, Watersprite, and duckweed (which my silver dollars regularly nibble) and there is a large piece of driftwood which keeps the tank at a steady 6.6 - 6.8 pH.

I have built a PVC pipe condo with 2 inch diameter pipes that are 12 inches long each, into a pyramid type structure consisting of 15 tubes held together by Gorilla glue. I would like to buy between 5 and 7 African knifes to put in here. I have had one before (a while back in a different smaller tank) which only ate frozen food and instantly spit out flake food when tasted. I have read that these knife fish are somewhat sociable, not to the point of schooling but in that they do hang out together and when being fed dry foods, they would be more likely to consume it due to competition. Is this a sound theory that is tried and true?
<I'm not sure where you got that info. According to Baensch: "Difficult, larger animals are solitary and aggressive towards other Xenomystus nigri". In other words, 1 per tank. I also think topping out at nearly 1 foot, you are dreaming of way too many knives in your tank.>
Is it fish dependant? Or will it just take some time to wean them off but in the end, most should be used to flake food? (with the bi weekly frozen food treat of course).
<Although fed a variety of foods (my knife lives with 7 discus) I have never seen my knife move from his hiding spot to eat anything on there than live worms. Although I read the fish can get used to strips of raw meat.>
And also, is the size of my tank large enough for such a mixture?
<I'd say that one of this species would work well with your set up.>
Right now, the silver dollars mostly stay at the middle level and the Corys are also at the bottom and never in the PVC pipe condo, so I figured that maybe this would be suitable. My last question being, will the knife fish get along when they get older or will they become antagonistic like other knife fish?
<No>
I just bought a new light which has moonlight LED's so now I can actually observe the knife fish swimming around without sitting in the dark and holding a small flashlight on the tank, so I am rather excited for this purchase.
<Cool!>
The only things holding me back are my high nitrates (about 120ppm +/- 40ppm) and fish compatibility.
<That IS high!>
I only hope that my new aquatic plants (with their new 260watt full spectrum fluorescents and actinic bulbs, as opposed to the old 60 watt mercury bulb) and removal of my giant canister filter (Fluval FX5 aka nitrate factory) will be enough to reduce the nitrates in the coming weeks. Thank you very much for your help and for having such a detailed site. I myself work as a chemist in a machine coolant company so I often read many things which actually pertain to my job, which is always a plus. Thanks again.
<Look into a large veggie filter for that tank.
http://www.thekrib.com/Filters/plant.html#8
Please note that when purchasing, most of these fish that are bought as juveniles do not survive the first month. Enjoy your knife! ~PP>
Matt, NJ

Clown Knife Fish Non-Live Food Training – 06/28/07
Hello, Your website is great! Unfortunately I could not find anything about training a Clown Knife Fish to eat non-live food. I've tried even warming krill/shrimp, I've tried Shrimp Pellets, Freeze dried Bloodworms, and Flakes. My 6" clowns just don't eat it. I have to revert to Live Ghost Shrimp, but I do not want too. Please help me find a way to train the Clown Knife to eat other prepared foods? Step by Step, please. As you know, Feeding time for these guys is only at night when the lights are off. Hope you can help? Thanks
<Greetings. Training Knifefish to accept dead food follows the same pattern as with any other opportunistic carnivore -- patience and a little starvation! As you realise, many people keep Knifefish by feeding them goldfish and minnows. This is very dangerous in the long term because of the risk of introducing parasites and the poor nutritional value (high fat and thiaminase content) of goldfish and minnows. So well done on doing the responsible, sensible thing by weaning your Knifefish onto safe alternatives. Small Knifefish are fond of (wet) frozen bloodworms, i.e., the kind you keep in the freezer. I have yet, in 20+ years of keeping fish, to find anything that likes freeze dried bloodworms or brine shrimp. I know people use them, but I've never had any luck with them. So get the wet frozen kind. These smell yummy and even difficult fish seem to accept them readily. If you train the baby Knifefish to take frozen foods, feeding the adults becomes very easy. Larger Knifefish in the wild eat fish, large insects, and crustaceans, so these are the things to concentrate on. One of the best ways to use frozen whitebait (or any other small, silvery fish) is to defrost it and then throw it into the current of water coming out of the filter. The flash of silver mimics the movement of small fish, and predatory fish will usually strike at the flash, and eat the food. I have personally found small pieces of oily fish (such as salmon or herring) extremely good for tempting predatory fish, presumably because of the smell, but be warned that oily fish *heavily* pollutes the aquarium and you will need to do a big (50%) water change afterwards. As well as fish, crustaceans like unshelled prawns and crayfish are excellent foods for adult Knifefish. If all else fails, alternate live foods, such as earthworms, mealworms, and crickets can also be used. Once the Knifefish learns to accept a variety of foods, tempting them onto floating pellets is not difficult. It helps if they share a tank with other fish that feed from the surface, like Tinfoil Barbs or Giant Gouramis. The Knifefish will see where the food is coming from, and take the floating pellets. Obviously, Knifefish are big and potentially aggressive, so don't mix with smaller fish or anything likely to pick a fight (like cichlids). Cheers, Neale>

Re: Clown Knife Fish Non-Live Food Training – 06/29/07
You guys are great! Thank you Neale for the information.
<You're welcome. If you love Knifefish, keep an eye out for a book called "Jurassic Fishes" published by TFH. It's a beautiful book, sadly out of print, but filled with the loveliest photos of Knifefish as well as other "monsters" like Arowana and gar. One of my favourite books! Neale.>

Feeding a Clown Knife
Hello guy's I just have a little question to ask.
I have a clown knife. it's probably six or seven months old (guessing). He has been eating Rosie's and small gold fish on a regular basis. He can eat about
two dozen in a couple of days. My question is this, would it hurt him to eat earthworms? He's only had two, but he loves them. Gobbled one up before it hit the bottom of the tank. Just wanting to know so that I don't hurt him.
>> No, earthworms are fine, he will likely eat some frozen foods also, try him on frozen Krill, smelts or Mysis! Good Luck, Oliver

Clown Knife Vision, Navigation - 09/02/2005
Do Clown Knifefish have good eyesight?
<Nope, pretty crappy, actually.>
Also, do they possess and use the electrical organ for navigation like Black Ghost Knifefish and Elephant Noses?
<These are actually very different from the clown knife.... The clown likely uses scent more than anything for finding food and such. Please see here for more: http://www.wetwebmedia.com/FWSubWebIndex/osteoglossiforms.htm .>
Thanks, Kristen :)
<Sure thing. Wishing you well, -Sabrina>

Clown Knife, Cory Cat - 08/16/2005
Greetings Bob,
<Hi, Richard; Sabrina here, this morning!>
This morning I noticed my clown knife had something in it's mouth and it turned out to be a Cory cat.
<Yikes!>
I knew that the clown knife ate live fish but I didn't think it would until it was much bigger. My knife is about 6-7 inches long right now.
<That's plenty big for any knife to start eating small fish.... These are very efficient predators.>
The Cory seems to be stuck in his mouth.
<Not good.... Chances are, he spread his dorsal and pectoral fins to prevent being eaten. I suppose it worked, sort of....>
It has been in his mouth now for a few hours. Is this normal?
<No, and yes. It's a normal reaction for the Cory to prevent himself being eaten, and it's normal for a clown knife to try to eat smaller fishes.... If the Cory is dead, and the knife is in obvious, extreme distress, I would try removing the Cory's pectoral fins with thin, VERY sharp scissors, then pull it out - GENTLY - or have a vet do so, if you've got a vet who would. If the Cory is alive, let 'em have some time to work this out. Watch the knife very closely for a while. This may work out fine on its own.>
This is the first time I have seen my knife eat live food. Please advise.
<Err, this is probably obvious, but whatever the outcome of this instance, remove all smallish catfish from the knife's tank, or you'll be sure to see this happen again!>
Warm Regards, Richard D. Warren
<Wishing you well, -Sabrina>

Clown Knife, Cory Cat - II - 08/16/2005
Sabrina,
<Hi, Rich>
Thank you for your help.
<Any time.>
Unfortunately my knife didn't make it.

I appreciate all your help though.
<I wish I could have been of more help. Perhaps in the future, you might look to Xenomystus nigri instead of the clown.... Though it might still have the same issue with small Corys and otos, it would stay small enough to be safe with larger Corys and other catfishes.>
Rich Warren
<Wishing you well, -Sabrina

Clown Knife not eating 7.23.05
I have a clown knife fish and I moved him from a 45 to a 75 and know he is not eating. He was eating at least 55 Rosies and mixed with some goldfish now he goes on his hunt eats maybe one or two. Its been two weeks since I put him in the new tank. Ph and everything is fine with water. Help me please
<As long as your water parameters are in good shape I would not worry too much, make sure he has somewhere to retreat to and hide in the new tank. He may still be getting used to his new surroundings. I am sure he will come around. -Gage>

Clown Knifefish system 7/10/05
Hi, I have recently just purchased a Clown Knife Fish and am confused about what PH the tank should be.
<Where they live in the wild the pH ranges from 6-8, so anywhere in that range, as long as the fish is properly acclimated, will work fine> So far my tank is at 6.8 as suggested by the place of purchase, but I have been reading that other people have their tanks set at 7.0 or higher.
<6.8 will work fine>
I really enjoy having my fish and don't want anything to happen to it. I have a 55 gallon tank right now and would also like to know any suggestions you may have on a good tank mate for my clown knife fish. I would really appreciate your feedback.
<Be aware that the clown Knifefish (Chitala chitala) attains 4 feet+ in length, and will most definitely outgrow your 55. It will eventually need a ~500+ gallon tank if you are to keep it to adulthood. As for tankmates, anything not too aggressive, and nothing that is a fin-nipper. If you're looking for big (for that future 500 gallon tank ^^) you could go with a 'Royal pleco'>
Sincerely,
Steve
<M. Maddox>

Clown knife problem 7/5/05
Dear Bob,
 I hate to bother you with this, however you seem like one of the only people that might be able to help me. I have a clown knife, approximately 7 inches long. He was accidentally overfed and became grotesquely bloated. I haven't fed him now in a month, yet the bloating has not gone down. I spoke to the owner of a local fish store who advised me to add salt to the water. I have been doing this but it doesn't seem to help. I have never seen this before and I am having a difficult time finding anyone who can help.
<Mmmm, what sort of salt? I would try a level teaspoon of Epsom (Magnesium sulfate) per ten gallons of water>
 Have you ever seen or heard of this before? If so, what should I do?
If not, can you refer me to someone? Thanks again for your time.
Warmest Regards,
Janet Sanders
<Some sort of gut blockage... what were you feeding? Hopefully not goldfish... Bob Fenner>

Re: clown knife problem 7/6/05
Dear Bob,
<Janet>
Thanks for the quick reply. Unfortunately, it is goldfish. I had fed my fish the night before leaving on a business trip. The next day, my son (not knowing I had just fed the fish), fed them again -- my fish has been sick since. What should I do?
Thanks,
Janet
<Try adding a level teaspoon of Epsom salt per ten gallons of system water... Hopefully this will "move" the blockage. Bob Fenner>

A budding pet-fish ichthyologist, Pantodon plants, Knifefish selection - 1/30/2006
Yes, I have... however I'm only fourteen and I don't think they'd take me.
<You might be (pleasantly) surprised here... Do speak with your parent/guardian re the time commitment, pledge to maintain your current school work, and look into arrangement of a "work permit" from your school, and ask the management to consider hiring you part time... This is how many of us "got started" in the industry... at and below your age>
I have two Big Al's, aquariums west and some Petcetera's (Canadian chain stores) nearby, though, so when I get older I will have some options. By the
way, I got the butterfly fish, I believe it is female as there are 13 rays in the caudal fin.
<Indicative in Pantodon>
It seems to have an appetite for, surprisingly, pellet food.
<Ah, good>
You'd think with that huge ramp mouth it might go after something else, but it just waits for the pellet food. She (?) won't even eat freeze
dried Tubifex or blood worms that float on the surface, and gets along great with my two new upside down cats (!!). Thank you for your valuable advice. I have moved my CAE into my 20 gallon hospital/quarantine for now because it is starting to get an appetite for my other fishes' slime coats.
<Am very glad for your close observation and action here>
I hope to give it away sometime in the near future, as it is around 4 or 5 inches, maybe 6 with the tail. By the way, I was wondering if you could give me some
advice on any floating plants for my tank?
<Sure>
I have heard that they keep the butterfly fish from jumping,
<Helps, yes>
and I only have some Cryptocorynes and Sagittaria right now. My tank is fully covered, but I do not want her hurting herself on the hood.
<Look for Ceratopteris... water sprite... my fave here>
I also checked Big Al's for knife fish while buying the African butterfly, and they carry brown knifes (Xenomystus nigri?)!
<Mmm, no... this is a Notopterid... a "Featherback Knife"... see elsewhere re S. American Knives... perhaps a search on Fishbase.org>
These apparently stay smaller, so I will look into them once I have a larger tank up and cycled. Thank you for all of your help.
-Eddy
<Welcome. Bob Fenner>

Clown Knifefish, Tiger shovelnose feeding, Toadfishes
Dear Bob and Associates,
I am a relatively experienced freshwater aquarist, but I have a little problem that I have never been able to find a solution to. I have a juvenile clown knife (Chitala chitala, 6") and a juvenile tiger shovelnose (Pseudoplatystoma fasciatum), and I am stumped as to what to feed them besides live foods (ghost shrimp and mollies/platies - never "rosy reds" or goldfish). I understand the enormous size these fish will attain, and I do not want to feed them unhealthy live fish (i.e. - goldfish) as they grow. Do any of you have experience with these fish? Since they're nocturnal, I assume that it would be best to try whatever non-live foods you suggest after lights-out in the aquarium.
<I would feed these guys glass worms, blood worms, plankton, mysis, etc. Live ghost shrimp on occasion. Pelleted foods if they will eat it. If you are going to continue with the mollies and platies you should gut load them with the above foods.>
I also have developed a huge fascination with toadfishes. I am particularly interested in the three-spine toadfish (Batrachomoeus trispinosis, commonly sold as "freshwater lionfish", though I know it's heavy-brackish to marine). Do you know of any web sites with comprehensive and DETAILED information on these fish (or toadfish in general...I have looked on fishbase.org, posted in the WetWeb forums, etc. and had no luck)? I would like to set up a "community of toadfish" fish-only marine tank, but I don't want to go into it blind.
<Unfortunately I do not have much information on these fish, I would start with a search on google.com. Have you checked http://reefcentral.com/
There is also some information at the link below
http://www.wetwebmedia.com/batrachoididae.htm
Best Regards, Gage>
Any info you could give (whenever it is convenient for you...no rush) would be greatly appreciated. Have a great day! Thanks, Matt Parkison

My new Clown Knife & Ropefish
I just purchased a Clown Knife (about 6"). I put him in a 25 gallon hex with a Rope fish and they seem to be doing fine. I've been told that both can grow quite large. Do you think they'll be ok or should I return them.
<Return them.... My clown knife grew to a length of 25 inches long! It is now living quite comfortably in a 650 gallon tank... It was originally living in a 150 gallon tank but outgrew that! The clown knife will reach 18 inches long in about a year and a half, this fish will NOT be able to live in a 25 gallon tank. As for the Ropefish (Erpetoichthys calabaricus) These fish will get over 36 inches long as adults... and require a 90 gallon tank. So, that too will not be able to live in a 25 gallon tank. I suggest you do some research before purchasing fish, there are many fish that will do quite nicely in a little 25 gallon tank. Many of them are just as interesting as these fish. Trust me it's no fun having a fish that is in a tank to small for it. These fish are sick all the time, and you have to constantly be changing the water to keep up with the waste output. Good luck. -Magnus>

Clown Knife
I am thinking of purchasing a Clown Knife fish and I was wondering what size of aquarium I should purchase? I was also wondering what are common tankmates for a clown knife?
<I raised knife fish for many years, and the Clowns are some of my favorite species! They get really (really) big, they usually stay around 2 feet long in the home aquarium. In the wild you can find these fish around 36 inches in length. The largest one I had was just over 25 inches long and was being housed in a 150 gallon tank. though she seems slightly cramped in there. I would say that a 150 is the bare minimum for an adult clown knife. I eventually moved her to a 650 gallon tank since she was so large. As for tankmates, Clown knife fish aren't aggressive. They don't typically pester other tankmates, unless they are very small. The other tankmates MUST be larger than the clown knifes mouth. If they are bite-sized fish they are gone! My clown was over 18 inches long within the first year and a half, and at that size it could easily swallow a 3+ inch goldfish. I kept a school of tinfoil barbs with my clown, these fish were about 8 or 9 inches total in length. The barbs were very active and didn't seem to get in the way of the clown at all. Also in the tank was a Pleco, and surprisingly a large Raphael catfish. It seemed that my clown disregarded any bottom dwelling fish (though not sure if it's true with all clownfish). As for other tankmates, the requirements are that they must be fast fish, in case the clown does get testy. The tankmates can not be aggressive, if a clown knife should become injured, or it's anal fin damaged it will not be able to swim. And the fish will stress itself to death. Cichlids are not to be kept with knives. And the biggest concern is that the fish need to grow faster than the mouth on the clown (which will grow quickly). They will need to be big fish. If these fish are larger than the clown can swallow, then the clownfish will not even care about them.
Other concern with the clown is that you will need to offer it a place to hide. I used a large piece of driftwood in my tank along with giant fake plants (4 feet long varieties). This made a natural looking wall for the fish to hide behind, thus making it more comfortable. I also found that I only left one side of my tank lights on (the side opposite the hiding spot). As well as have one of the plastic plants floating on the surface of the water, shading much of the tank. Clowns prefer to hunt at night, and don't typically come out during the bright day. Doing this I found my clown would tend to come out more often during the day without the intense lighting. Be sure to get your clown on food other than live fish. I spoiled mine when it was young by only feeding it feeder fish and when it was older I couldn't get it to switch easily. I found myself purchasing 2-3 dozen goldfish ever couple of days to feed it. Fact: An adult clown knife can eat 2 dozen medium sized goldfish in a single night. Good luck on the fish. They are very enjoyable, and quite impressive. -Magnus>

Everybody To The Limit! - 04/13/2004
I purchased a knife clown about 5 days ago. He's about 3 to 4 inches long.
<Aww, just a little baby! Just to check, you do realize that these beauties get over four feet long, yes?>
I have him in a 30 gallon tank with 2 gouramis, 2 tiger barbs, 2 angels, a large pleco, a 4 inch silver dollar, a small Cory cat, a small tetra, and a kuhlii loach.
<Uh, and a partridge in a pear tree?? This is, nicely put, a little much for a 30 gallon tank, I'm afraid.>
I realize knife clowns grow rapidly and that I will not be able to keep this one in my tank for long.
<Or any tank.... A few hundreds of gallons would do for a couple of years.>
However, I have fed him fish flakes, freeze dried plankton, freeze dried Tubifex worms, brine shrimp and feeder guppies, and he has exhibited little to no interest in any of these. I have yet to see him eat, though he swims around freely during feeding time.
<Try frozen bloodworms, pieces of krill, squid, prawn/shrimp.... and skip the feeder guppies, unless you breed them yourself; they run a *terribly* high risk of giving your fish disease.>
All the other fish chowed down. I have also noticed that his fins are nipped.
<Uh, not to be cruel or anything, but what do you expect? A thirty gallon tank is not suitable for the sheer volume of fish you've got, and *especially* not suitable for a knife capable of growing taller than your average school kid.>
I have noticed the silver dollar nip at him a couple of times.

Any suggestions?
<First and foremost, I would forget about the knife for now. I hate to be harsh, but there is just not a place in your tank for such a fish right now. If the stress from the crowd doesn't kill him, the barbs and silver dollar will, I'm afraid. Then I'd recommend focusing on how to hone down your bioload some; characins are schoolers, and need to be with others of their kind to thrive; you might consider doing a separate tank for the silver dollar, and get him a couple pals, and include the barbs in that tank, and the tetra with some friends, too. That would take you down to two Gourami, two angels, a pleco, a Cory, and a Kuhli in your 30g. The plec will be next to need a bigger home, if he doesn't already; you implied that you planned on moving the knife to a bigger tank - perhaps instead, you could upgrade, and move this batch (Gourami, angels, plec, Cory Kuhli) into the bigger tank, leaving the characins in the 30g? I'd add a couple more Corys and a couple more Kuhlis, too; they, too, are better in groups. Then, after that's settled, you might like to consider Xenomystus nigri, the African Knifefish, for your larger tank. This is really the only knife available in the trade that will not grow far too large for the average tank; they top out at about eight inches. Here's fishbase's rundown on 'em: http://www.fishbase.org/Summary/SpeciesSummary.cfm?ID=5065&genusname=Xenomystus&speciesname=nigri .>
I am at a loss for what to do next.
<There is really nothing you can do to make the current mix work.... I do not foresee the knife surviving in the current scenario. I hope that this has been of assistance to you.... Please forgive the "nagging"; I only have the interests of you and your fish in mind.>
Thank you in advance, Mariella
<Wishing you and your finny pals well, -Sabrina>

Ghost Knife Changing Colors
What causes a black ghost knife to start to lose its color and turn a silvery white?
<The first thing I would do is test my water, poor water quality, stress, age, diet, there are many things that can attribute to these fish changing color. Gage>

Clown Knife and Algae Eater
Hey, I just bought a large-size clown fish with 2 other medium-size tropical fish in a 55 tank. I've learned that the knife is a predator and will eat anything smaller than its mouth. I'm concerned that if I put an algae eater in, the knife might swallow it as food.
Since my tank is full of plants and rocks, it'll be difficult to clean the algae. What should I do!? Thanks for your time.
<<Hello. The best way to control algae is by doing waterchanges. Once your tank is established, test your nitrates regularly, and do the waterchanges accordingly. Algae thrives on organics in the water, and even the best filter will not prevent build-up of organics, you need to remove them by doing partial waterchanges. Especially with a large predator in your tank, weekly waterchanges will be necessary. Is this tank still cycling now? You must test your ammonia and nitrites as well, each week! And keep in mind that your clown knife will eventually outgrow a 55 gallon tank. You will need to upgrade if you want to keep him alive.
-Gwen>>

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>

African Knifefish - 11/03/2004
I recently bought a brown knife fish.
<Xenomystus nigri.... Usually called the African knife, sometimes sold as the brown knife. Is this your fellah? http://www.fishbase.org/Summary/SpeciesSummary.cfm?genusname=Xenomystus&speciesname=nigri There *is* a fish more similar to the black ghost knife referred to as the brown ghost, but I've only seen this fish once or twice offered for sale.>
(It's been about 10 years since my last aquatic impulse buy. I was due.)
<Tsk tsk.... ;) >
I put him in a 55 gallon aquarium containing 5 hatchets, 7 harlequin rasboras, 5 zebra danios,
<All of these may one day be food....>
1 sunset gourami, and 3 Cory cats. He doesn't seem to be bothering any of them. He's only about 4" long now. Brown knifes don't get as big as clowns, do they?
<Hoo, goodness, no! The clown gets over four feet long! The African knife is, perhaps, the *only* regularly available knife suitable for your tank, topping out at about 12", and often a bit smaller than this.>
Will my tank be big enough if I don't add any more fish?

When he gets bigger, will my other fish be in danger?
<Plausibly. I would try very hard not to be too attached to your smaller fishes, right now....>
Since I don't get to see much of him, how do I know if he's getting enough to eat?
<Feed after lights-out on the tank. Leave a small light on in the room the tank is in; just enough for you to see by. After waiting an hour or so, sneak in with some stinky yummy treats (I've seen these relish frozen bloodworms like nothing before!) and wait until he finds it. You can use a cone-type worm feeder. If this doesn't get him biting, you might try live ghost shrimp or live blackworms; the former is the "healthier", "safer" choice.>
How do you feed live earthworms to them?
<After lights-out, try holding the worm by hand so that some/most of it is in the water near the knife. Wait. See if he bites. Don't fear, eventually this fish will be easier to feed, and will recognize you as the bringer of treats.>
I know from past experience (with fire belly newts) that they try to burrow into the gravel before they get eaten. How do I keep the worm where the knife will find it?
<Again, try by hand, or perhaps you could use a dish of some sort to place the worm in?>
I really appreciate any advice you can give me.
JoLynn
<Good luck with this new knife.... One of my favorite oddities, by far! Wishing you well, -Sabrina>

Feeding Clown Knife – 03/17/07
Hi –
<Hello Ray, Brandon here.>
I’ve had a clown knife for a couple of months now, and during that span it has grown from 3 – 4 inches to 6 – 7 inches. At first, when he was smaller, I fed him a combination of brine shrimp and blood worms (frozen) along with small (not goldfish feeders) fish. However, I had to leave for college during that time (I got it during my winter break), but not without telling my parents what I would like them to feed it (e.g. continue feeding it brine shrimp and blood worms along with the occasional fish). However, they started to feed it the minnows that are commonly found in pet stores.
<Mmmmm. Minnows are bad news. This is a really good way to introduce disease into the tank, and to your fish. Ever hear of hole in the head? This is one of the ways that your fish can get it.>
So, upon coming home for spring break, I find that my clown knife refuses to eat anything other than brine shrimp and blood worms along with live fish.
<Define anything. Have you tried any other crustaceans?>
Given his size now, wouldn’t brine shrimp and blood worms be too small and not nutritious enough for him?
<Depends on how much you give it. It is never a good idea to stick to one variety of food though.>
I went out and bought frozen krill in order to try to wean him off of live fish but he refuses to eat them. He just lets them drop to the bottom before proceeding to ignore them (the first time I
put them in he ate one but then quickly spit it back out and since then has ignored them).
<Seems that the Chitala chitala does not regard these as food.>
I even tried cutting the individual krill into smaller bits in case they were too large for him. Thus, I have not been feeding him anything lately (this has gone on for about 3 days now). Just wondering, how
long can I go without feeding him without starving him to death?
<Three days is not going to starve him, but it will definitely stress him. I would say it might take a month or more before he starves to death.>
Also, what is the best way to wean him off of live foods (save for an occasional snack) and what food should I use to do this (if not krill)?
<Krill is not really a part of this fish’s natural diet. It is quite possible that you will never wean him off of live food. I have had to come to this realization, with one of my saltwater fish. I would say that the best way to proceed when faced with this sort of thing, is to set up a 10 gallon tank, with some gravel, and a plant or two, and put about three dozen ghost shrimp in it. Feed them a high quality food (gut loading), and give the Chitala chitala about three - four a day. If it is taking blood worms, you might try mixing something that you want it to eat with them, eventually the fish will ingest the other food, and could start to recognize it. Another resort is to try a small piece of store bought fish attached to the end of a feeding stick, wiggle it around and see if the fish takes it.>
Finally, I have one final question that has nothing to do with feeding him…… sorry.
<No worries.>
I plan on building a new tank him during spring break, but I have read conflicting reports as to how large they will get. While I know that they grow to 4 feet in the wild, I have read that they usually don’t grow past two feet in captivity.
<I don’t usually show up late for work but it happens. I would plan on a four foot max length just to be on the safe side. There is no guarantee that this fish will get to four feet, but there is no guarantee that it won’t either. Everywhere I have seen them sold, I have seen a sticker posted that stated that the max length was 48 inches.>
However, I have also read in some places that they can grow up to 3 – 3 ½ feet in captivity. So my question is this – how large can I expect my clown knife to get and based on this, what size tank should I make with what dimensions?
<I would plan on four feet. I would also advise you to go and buy the tank. Shoot for 150 gallons. It will cost about the same to buy the tank, as it will to make it, and the store bought tank will most likely be (not to insult your abilities.) more well made. But since you asked, I will say that the dimensions should be something like, 72 ½ inches long, 18 ½ inches wide, and 28 ½ inches high.>
Thanks for taking the time to read this long question and thanks for making such a great website (I’ve read through many articles and FAQ’s just for fun…. Wait, is that bad? :-) ).
<You are most welcome. Thank you for the kind words. Good luck with the Chitala chitala. Brandon>
-Raymond

Freshwater tanks - African Knifefish question, cichlid in/comp. 12/28/06
Hi there.
<<Hi, Stacy. Tom here.>>
Can I put a Black African Knife Fish in with a couple of African Cichlids? Just starting a new tank and am not sure of this.
<<It depends a great deal on the size of the tank that you’re starting, Stacy. Less than a 50-60 gallon tank would be too small. These fish can grow to a foot in length.
Factor in the size of the fish you want as tank mates as well. Compatibility-wise, they need to be with large fish since smaller fish might look like “lunch”. (Tank size again.) You’ll need to provide cover, i.e. hiding places, for them since they’re not particularly active during the day. Beyond this, your question is a bit difficult to answer without more information regarding what I’ve already mentioned and the species of Cichlids you’d like to house your Knifefish with.>>
Please help. Thank you.
Stacy
<<You’re welcome even though it’s only a start. If this isn’t enough to go on, you know where to find us. :) Happy Holidays to you. Tom>>

Clown Knife Life-spans in wild/captivity - 12/07/06
First thanks for the excellent site and knowledge, when all else fails
you guys have the answers.
<Welcome>
I have been researching the Clown Knife (specifically Royal Clown Knife - Chitala blanci) life-spans. I am about to adopt a pair from a friend that have been raised in a 300 gallon tank for the last 2 years from 4" to 16" each. I am moving them both into a 240 Long (96x24x24). I am very interested in the average lifespan of them in captivity or in the wild. Can't seem to find much on the net to support an educated guess.
I have read that they rarely grow past 24" in captivity, but can reach 4' in the wild (may be pushing it IMO).
Thanks for any insight you can provide.
Joe
<I've been to the "new" Bangkok aquarium just two months back... and they have some Notopterids of this and related species that they've had for teens of years. Unfortunately fishbase.org doesn't have a chart/data for this species' length/age relationship... in the wild. Bob Fenner>

SICK JACK THE KNIFE
I have an African Knifefish and it is pretty hard to find useful information about this species. I have a 55 gallon tank that recently got ich as a result of a fairly new clown loach. The loach died and gave it to a danio and another loach I had. I raised the temp to 85 degrees and I have raised the salinity to 1.003. (Over a period of a few days of course). The loach's spots went away as well as the danios and I haven't found any other traces of ich.
Things have not been going well however. Yesterday, I found a dead African dwarf frog and today I found a heavily bloated danio who is probably dead by the time you read this. My other danio looks like his stomach is protruding a bit as well. I checked my knife and he has these two big patches of white. I didn't know if it was ich because it isn't small dots it is a very large patch (about 3cm) and another patch (about 1 cm).
I have two small Plecos that I haven't noticed any problems with and I really don't want anything to happen to my knife. Are the large patches ich or something else? They have just showed up today and were not there yesterday so I am
catching it pretty early. Any suggestions? Thanks for any help and great site.
< Your tank is breaking down from the water treatments. Drop the water temp to 78 to 80 degrees. The high water temps are stressing your danios and causing the bloat. Do a 30% water change, and vacuum the gravel. Service the filter too. Check the ammonia and nitrite levels, they should be zero. Check the nitrates. They should be lower than 25 ppm. Now that the tank is cleaned up you need to treat those bacterial infections on the knife fish. Use Nitrofurazone and back off on the salt. This medication may affect the good bacteria that breaks down fish waste so watch for ammonia spikes.-Chuck>

Request for bibliographic help on the Featherback Knifes, Notopteridae
Dear sir
This is sathish s v from India working for PhD on induced breeding in fish n notopterus . hence I am in need of your valuable references (reprints) related to the above .kindly send them to the below find address.
<What little I have is mainly pet-fish related and referenced (the intended use) and posted here on our site: http://wetwebmedia.com/bonytong.htm
Bob Fenner>
SATHISH S V
DEPARTMENT OF ZOOLOGY
GULBARGA UNIVERSITY
GULBARGA -585106
KARNATAKA, INDIA

Clown knife with a bulge
My clown knife looks as though it has swallowed a small rubber ball.. the kind that you get out of a gumball machine... All of my other fish are still in the tank and still have all of there parts... my clown knife will not eat now but is moving around fine...
<Is the clown producing feces at all? If so, is it normal and brownish, or white and stringy?>
We have had Mercury for 2 months now and have NEVER seen this before... I understand and have seen the "bulge" after eating, but this is NOT that!! The bulge he has now is huge and very round, again, like he swallowed a rubber ball.. no other way to describe it...
<Sounds very much to be a gut blockage or constipation. I'd suggest to dose the tank with Epsom salts at a rate of 1 to 2 tablespoons per ten gallons (this *should* help), and if the fish looks like he may accept food tomorrow, offer daphnia or mosquito larvae, or possibly (depending on size of the fish) a small earthworm, if the other items are too small for him. These foods are high in roughage content and may possibly help to pass the blockage.>
The owner of the local pet store thought maybe it was a bladder infection
<Hmm.... a swim bladder infection is characterized by abnormal swimming (and occasionally accompanied with dropsy) - I do not believe this to be the case.>
and told me to wait until tomorrow and see how he was....
<Go ahead and dose with Epsom salts tonight, it may very well help a great deal.>
I cannot find ANYTHING on the net regarding this.... CAN YOU PLEASE HELP?????
<I do wish to bring up another issue that this may be - there's the possibility that this is a tumor. That you seem to imply that it happened suddenly and that the fish is not eating lead me to think constipation far more likely. If it is a tumor, though, there's really nothing to be done, unfortunately. Hopefully you'll see some improvement soon.>
Thank you in advance.... Heather O
<Wishing your fish a quick recovery, -Sabrina>

Clown knife with a bulge - II
THANK YOU very much for the speedy reply!!!!!
<You bet!>
This morning when we checked in on him.. the one side has gone down completely and the other side is much smaller but now , no other way to explain it.... but it looks like a huge zit with a white head... half an inch long by 1/8 of an inch wide...
<Hmm. That doesn't sound good. possibly an injury, perhaps infection....>
it definitely looks better than last night at 9:00pm....
<That's certainly a good sign!!>
as for producing feces.. I am not sure...
<Sounds like he passed the most of it. Still, do try to feed foods with a high roughage content for a few days.>
Mercury is about 7 inches long now... and has been doing wonderful until last night... he gets along great with our other clown knife Neptune, who is about 12 inches.... we also have a convict, a scat, an iridescent shark, and a plecostomus...all live happily together....
<You seem to have a taste for the very, very large.... Ultimately, hope you've got a really big tank! ;) >
He still isn't eating... but as I said.... I think that he looks much better....
<Good.>
Again, thank you SOOOO VERY MUCH for the speedy reply... this is a site that I will keep handy in the future!!!
<Excellent. Pass it along to all your fish friends, too!>
Oh, I almost forgot... I do have aquarium salt in the tank... but will add Epsom salt if you still think that will help!
<I do think it would help, perhaps, especially if Mercury is still a little bloated. Also, please keep a *close* watch on that strange mark - if it's an infection of some sort, you'll want to quarantine and treat with an antibiotic. Hope all goes well, and glad to be of service! -Sabrina>
Heather O

Clownin' Around - Clown Knife Behaviour - 12/03/2004
I have a 55g. tank with two clown knife that are about 6 inches in length, along with a glass cat, a Pleco, and a fiddler crab.
<A few problems, here - not the least of which is the size and territoriality of the clown knives. Please note that the glass cat may likely end up as clown food, and the fiddler crab really requires a way to get out of the water for long-term survival, and really ought to be in saltwater - or at least brackish conditions.>
They are all doing great together, however, my one clown will go over to the other side of the tank near the other clown knife. They do not pick on each other but they rub their bodies together for a few seconds then they go their separate ways.

Also when the one clown gets close to the other one, he ends up rubbing his body up against the rainbow rock I have in the tank. He does this in front of the other knife fish only, like he is marking territory or showing off. I see no signs of any parasites, no ick, no frayed fins, great appetites as well.

My knifes even come out and swim during the day until I get too close to the tank. All in all, I have been watching them very closely for any signs of illness, I am out of practice as far as fish, I worked in a great pet store for 10 years and kept up to date on every single animal we sold so that I could give the best information as well.
<Always wonderful to hear of reputable fish stores - thank you for being informed on your livestock!>
But clown knives were not one on my list, my boss took care of those strictly. Can you think of any other reasons why the clown knife would be doing this in the presence of the other clown knife only?
<If there are gill parasites or another ailment at play, it could be purely coincidence - perhaps the "best" rock to scratch one's operculum on just happens to be next to the other knife's digs? Otherwise, again, I might attribute this to a display of aggression/territory, as you suspected.>
He doesn't do it any other time at all and the temp is usually around 78 degrees F, ph is around 7.0, I keep up on water changes and monitor levels and test regularly as well.

Also I was keeping a few red eye tetras, some head standers, zebra Danios and some swords in with the knives. I had to take them all out and put them in another tank because the knives were tormenting them to death.
<Heh, yeah - all of those would make tasty snacks for the knives!>
A few got ick and the knives are still fine after I took the other fish out. Which they did eat a few of the Danios and a red eye as well.
<This is concerning. How long ago were the fish removed? It is quite possible that the knife does, in fact, have ich on its gills.>
I know they are eating well. I read all the info you have given to everyone on knife fish and it was very educational for me as well.
<So glad to hear this!>
However I did not see in great detail about the actual personalities these fish generally have.
<Well, to be honest, not a great many folks can really provide adequately for this species.... Cared for properly, the fish can and should grow to be roughly four feet in length - a four-foot fish requires a *much* larger tank than would easily fit in the average living room. And keeping them just while they're young isn't really the greatest idea - what will you do when they hit a couple feet, have outgrown the 250 gallon tank you've upgraded to for them, and can't find a public aquarium that is willing to take them on? Please think very seriously about the ultimate size of this fish, and what you plan to do as they age. If they are already intolerant of each other at six inches in a 55g tank, imagine what they'll do to each other in another foot or so, if they allow each other to live that long.... At the very least, I would remove one of the knives.>
Sorry this is so long but this is pretty much the only web site I could find that has a lot of valuable info on it pertaining knife fish.
<And thank you very much for writing in, and thereby helping us expand the information available.>
Also if you think my clown knife does have parasites or some other disease, what should I be treating him with? I know there are many meds out there not to be used for scaleless fish, and I suppose the parasites will spread to the other fish in the tank as well?
<You are correct on both accounts - knives, especially, are tremendously sensitive to most medications. I would avoid treating the fish with medicines at all costs. Watch the "scratcher", and if you begin to suspect that he has ich, I would add salt to the tank. Be sure to use a salt marketed for freshwater aquaria, and test on a sample of your tank water first to ensure that the salt will not alter your pH undesirably. I would slowly (over a few days) raise the temperature to the mid-80s (84*F-86*F), increase the salinity to a specific gravity of 1.003 (use a good hydrometer to measure this) and hold it there for at least a week - perhaps a little longer. Always make salinity changes VERY slowly - spread the change out over a few days. The ich cannot survive at this salinity, and the temperature increase will cause the ich to speed up its lifecycle to bring it to a vulnerable (killable) point in its development sooner.>
Thank you for any info you can give to me.
<And thank you again for writing in. It seems as though you greatly enjoy the knifefishes. I would like to recommend, if you choose to relocate both of the clowns due to size issues, that you consider Xenomystus nigri, the "black" or "African" knifefish. This little fellow won't get much more than eight inches in length, and has many of the same qualities of the clown (same general shape, temperament) packed into a MUCH more manageable size. Though it lacks the beautiful markings, it is still a very attractive, very interesting fish, and I highly recommend it. It would live quite well and happily in your 55g, for the full duration of its lifespan. Please feel free to write back if you have any further questions, and thanks again for writing in!>
Shannon
<-Sabrina>

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