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FAQs on Featherfin/Notopterid Knifefishes Behavior

Related Articles: Featherfin Knives, Bony Tongue Fishes, Arowanas, Arapaima, African Butterflyfish, Featherback Knifes, Mormyrids, ElephantfishesNew World Knifefishes, Black Ghost Knife,

Related FAQs:  Feather Fin Knives 1, Feather Fin Knives 2, & FAQs on: Feather Fin Knife Identification, Feather Fin Knife Compatibility, Feather Fin Knife Selection, Feather Fin Knife Systems, Feather Fin Knife Feeding, Feather Fin Knife Disease, Feather Fin Knife Reproduction, & by Species: African Featherfin Knife, Xenomystus nigri, Clown Knife, Chitala ornata, & Bony Tongue Fishes, Aba Aba Knifefish, South American Knifefishes, African Butterflyfish, Arapaimas, Arowanas, Mormyrids,

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>

Clown Knife Behaviour - 11/01/2005 My (Clown) Knife often breathes from the surface (I read that they are capable of breathing atmospheric air) is this in any way stressful for him?  <Uhh, no, not unless water quality is forcing him to do so.> If so would adding an air pump help this situation?  <I would test water quality - be sure to maintain as optimal (0 ammonia, 0 nitrate, less than 20ppm nitrate).> Also, he/she has recently begun keeping its mouth open constantly with it's tongue partially out. Is this an indication of anything bad? <Possibly so. With no information about your system, there's not much I can go off. Do please be testing your water.... if it is not optimal, make it so with water changes. Wishing you well, -Sabrina>

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>

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. <I would assume that this is either courtship or aggression - and far, far more likely to be aggression.> 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. <I would guess this is part of the aggression issue - but possibly an indicator of gill parasites.  Please observe the fish for heavy breathing or any other abnormalities.> 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.   <I am assuming, then, that ammonia and nitrite are at zero, and nitrate is below 20ppm?> 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!> <-Sabrina>

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