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FAQs on Black Ghost Knifefish, Apteronotus (Sternarchus) albifrons, Compatibility

Related Articles: New World Knifefishes, GymnarchusNotopterids/Clown KnifefishesElectrogenic Fishes,

Related FAQs:  Knifefish Compatibility, BGK FAQs 1, & FAQs on: BGK ID, BGK Behavior, BGK Selection, BGK Systems, BGK Feeding, BGK Disease, BGK Reproduction, & Knifefishes 1, Knifefishes 2, Knifefish Identification, Knifefish Behavior, Knifefish Compatibility, Knifefish Selection, Knifefish Systems, Knifefish Feeding, Knifefish Disease, Knifefish Reproduction, Electrogenic Fishes, Notopterid Knifefishes (Clowns...),

NOT w/ mean fishes, nor ones that will outcompete it for food


Re: Got My First BGK; multiple Mormyrid stkg.      5/1/17
If you can stand yet another question from me, I was hoping you could clear up some information (or, possibly, misinformation) I found on the internet.
I have read that you cannot (or at least should not) keep more than one mormyrid in one tank.
<Does depend on the species. Some are quite sociable, and do well in groups of 6 or more specimens. Indeed, most of them probably are social in the wild, certainly the class Elephantnose seems to live in big schools, but the sheer size of the standard Elephantnose makes this very difficult to accommodate at home. Singletons can do well, becoming fairly tame if looked after well. A big group should be fine too, but unfortunately in twos or threes they tend to squabble unless the aquarium is very large, so they're rarely kept in groups outside of public aquaria.>
They say that the electrical impulses these fish use to find food would conflict and potentially cause both fish to starve.
<Correct. Dominant specimens hog the best frequencies, forcing weaker specimens to use less effective ones, making it harder for them to navigate and find food. Not a problem in the wild where a big school of them couldn't be dominated by a single specimen for any length of time, but in the aquarium, it can be a bully's paradise with so little space available for weaker fish to move out of trouble.>
I have no intention of getting any more BGK's, but I keep thinking about the little Elephant Nose. I'd love to have one, and their water parameters are consistent with the BGK, but I don't want to cycle up another tank right now.
<I would not mix Elephantnoses and Black Ghosts in the same tank, at least, not without a Plan B if it turned out the two species didn't get along.>
Also, I'm concerned that because the BGK comes from fast moving waters and the Elephant Nose lives in slow moving water, that the Elephant Nose would suffer in the same tank.
<Quite so.>
Again, this is not something I plan on doing in the near future as I have my hands full with the BGK. I guess you could say I'm just starting to research.
<Do review some of the smaller, more sociable members of both these groups. The Glass Knifefish (Eigenmannia virescens) for example is fairly widely traded, and small enough that maintaining a group in, say, a 55-gallon tank
wouldn't be impossible. Such a species could cohabit with tetras and catfish, if all were chosen with care. Similarly the Baby Whales (various Pollimyrus and Petrocephalus species) are smallish relatives of the Elephantnose that are viable in groups if you have the space. Cheers, Neale.>
Re: Got My First BGK     5/1/17

Thank you again! But I've got my heart set on an Elephant Nose.
However, given your advice, I think its best that I just focus on the BGK for now and put off getting the Elephant Nose until sometime in the future when I'm able to set up a tank just for that fish.
<Wise. Although good community fish in the sense of cohabiting well with small African tetras and the like, their special food requirements do mean they're poor choices for rough-and-tumble set-ups alongside species such as
non-herbivorous catfish and loaches that might compete for food. They can be picky eaters, but not excessively so, and will adapt to a range of foods. I memorably saw an adult specimen consuming vast quantities of baby brine shrimp!>
Thank you so much for all you do!
<Most welcome. Neale.>

Black ghost knife - quarantine and tank mates.     11/1/16
<Hello Ranjana,>
I'm finally setting up a tank for a black ghost after waiting for almost 8 years :D starting it out with a 60 gal tank, slightly planted.
<Sounds good, though 60 gallons will be small for the size of adult fish.
So be aware, at some point a bigger tank will be necessary -- if all goes to plan!>
I've read up most of the information available on the internet regarding to these fish but since they're very sensitive to medications i wasn't sure about how to go about the quarantine process like what all to treat it with, dosage and for how long.
<Basically, don't medicate; isolate. Keep the Black Ghost Knifefish on its own for 6 weeks. In that time, if it shows any sickness, use very specific treatments. Antibiotics for bacterial infections, salt/heat for Whitespot.
That sort of thing. Avoid "general cures" like Melafix, and definitely avoid anything containing copper or formalin, both of which are extremely toxic to these fish. Medicines described as "safe for cartilaginous fishes" such as sharks and stingrays should be safe to use. Your other challenge is to get your Black Ghost Knifefish feeding! You want a wide variety of foods, not just bloodworms. The bigger the range of different things your Knifefish will eat, the better. More small meals per day is better than one big meal. Most of all, you want your fish to have a nice rounded belly, not
swollen, just gently rounded. Such fish will be healthy and putting on weight. Once you're sure your Knifefish is feeding well, you can then add tankmates, ideally non-bottom feeders (like Angels) first, and over the months, other types of fish (like the loaches) that might compete for food.>
coming to tank mates i was thinking of :
1 Senegal bichir or an Albino Senegal bichir ( which would you recommend?)
<Good choice. Very similar in temperament, but Bichirs are sold at bigger sizes, so I'd get the Knifefish settled and feeding first, for a few months ideally, then add the Bichir.>
4 yoyo loaches
<Also good, provided they don't eat all the food.>
a couple of silver angel fish
<Also good.>
also i got a electric blue Dempsey recently. still a baby about 2 inches and i was wondering if he can be kept with the BGK. sounds risky but i did read in a few places that only one can be kept successfully in a community tank.
<I would not keep a territorial, aggressive cichlid with a Black Ghost.
Juvenile Black Ghosts are very delicate and slow feeders, and you'll find most cichlids cause them stress. Adult Black Ghosts are a bit tougher, but still, not worth the risk.>
Thank you so much in advance,
<Most welcome. Cheers, Neale.>
Re: Black ghost knife - quarantine and tank mates.     11/1/16

Thank you for such a quick response :)
I'm planning to get a 150g set up by the time he hits 8-9 inches.
About the antibiotic, will erythromycin be fine?
<Can work, but bear in mind Erythromycin works only against some bacterial infections.>
also should i stick to half a dosage recommended? cause' I saw a couple of videos where it suggested to stick with full dosage as half a dosage might not help with the issue and might make the fish resistant to the medicine ?
<Absolutely! Unless a doctor or vet tells you to reduce the dose, use the full dose. Your research is absolutely correct in that half-doses (and not finishing the whole series of doses) can lead to antibiotic resistance. And that, as you know, is VERY bad.>
Also the other thing i was a little worried about was the ph. The tap water ph here is about 7.4 which is generally high for them. But im caught up between setting up the tank with a lower ph water or get the fish acclimated to the tap water ph? I'm guessing the lfs here also have the same ph. I'm torn between giving them the ph they're supposed to be in to
giving them a consistent ph.
<Water chemistry is not too important. Medium hard water up to pH 7.5 is fine. Black Ghost Knifefish are MUCH more sensitive to poor water quality.>
As for the food, I thought I'd start him off with Hikari carnivore pellets then slowly bring him up on fresh food like earthworms, shrimp and tilapia once he gets to a reasonable size. also your thoughts on Spirulina for bgks? and vegetables like cucumber and spinach. Some of the things i came across while looking into the food.
<Try everything! Variety is CRUCIAL. If your specimen likes Spirulina, then great! They are micropredators though, so Spirulina-enriched frozen brine shrimp will probably be the easiest way to get "greens" into your Black Ghost Knifefish.>
would you recommend mixing the antibiotic with food or dosing the water?
<Giving in the food is ALWAYS better for systemic bacterial infections (like simple failure to thrive). But adding to the water is probably just as good for treating external infections like Finrot. Adding to the water tends to be hopeless for systemic infections though. So as we say in England, "horses for courses" -- you identify the situation you're in, and
choose a dosing method as required.>
And the juveniles we get around here are about 2-3 inches, is it okay to get them or should i go for a slightly bigger one?
<Ideally, yes; very small fish (relative to adult size) tend to be rather delicate. The ideal specimen is probably around the 12-15 cm/5-6 inch mark... but MUCH more important than size is how well fed it is (and how aggressively it feeds!) when you see it in the shop. A small, but pushy, fish that's happily eating lots of food will be much better than a bigger
fish that hasn't eaten for weeks. Make sense?>
I'm tempted to get a smaller one cause' I want to see him grow from a tiny little spec to a massive fish.
<They grow ever so slowly, so this can take a while! In fact hardly any reach adult size because not many people keep them for anything like a normal lifespan. I've seen one or two adults over the years, and they're massive fish! But most people buy youngsters that live for a year to two before dying for some reason -- usually lack of food (they have BIG
appetites) and/or poor environment (they need lots of space/lots of oxygen).>
Thank you so much again.
<Cheers, Neale.>
Re: Black ghost knife - quarantine and tank mates.      11/9/16

Thank you so much for helping me out last time, so as per the advice on the quarantine process for the black ghost,
I set up a 20 gallon so its easier to keep an eye on fish too see if its feeding and excreting properly.
But i noticed that my tap water ph is about 8.2. I know this is too much for bgk, but is it possible to acclimate it to this ph?
<Yes, but unwise if you aren't changing hardness as well. It's the hardness, not the pH, that causes problems for fish.>
I did read in a few webpages that it is possible but, i wasn't comfortable to trust that hence asking you. I cannot afford to get an RO system installed right now. I'm still a student. The only other way is to get canned drinking water, but I'm afraid it wont be available in emergency situations.
<I would not worry too much. I would focus on water quality and diet.>
Now i could decrease the ph of the water with driftwood and almond leaves, but I'm worried about the ph swing during water changes.
<Indeed. A slight and slow pH drop between water changes won't be too bad, provided you do small water changes periodically. But you would have to measure pH regularly, probably several times a week for the first couple of
months, until you had a good idea of how pH changed (if at all).>
The other thing I thought of was, setting the tank up with the canned/drinking water (ph of about 7.4) and doing a 10% water change twice a week with normal tap water. would it still be a huge ph swing? will this work?
<It's not a bad idea at all! Set the tank up with your tap water first.
Then over the next few weeks, make small changes to water chemistry by doing 10% water changes every few days, even once a week. See what happens!
So long as hardness isn't lowered to zero, and pH doesn't fluctuate wildly, you'll be okay. Put it this way: do a water chemistry test on your drinking water. Let's say it's 5 degrees dH, pH 7.4. Then you test your aquarium water, and it's 20 degrees dH, pH 8.2. If you mix the two, 50/50, at each water change, you will eventually end up with a tank around 12 degrees dH, pH 7.6, which would be absolutely fine.>
I'm reconsidering getting the fish and its breaking my heart. But I'd rather not get it than make it struggle in a high/unstable ph.
<A high pH is not necessarily a deal breaker; but an unstable pH is. See above. If the Black Ghost Knifefish is adapted to your local hard water, and is feeding and growing merrily, it could live a long and happy life, provided water quality is excellent.>
I read that letting the water age with aeration helps reducing the ph a bit?
<Depends on the water chemistry. Aerating doesn't do anything by itself.
But some water has lots of dissolved CO2, and aerating drives this off, raising the pH. That's the commonest scenario.>
but It'd be very difficult to do water changes for a 60 gal/150 gal that way and isn't very practical. I am very confused as how to go about this.
Out of topic, but is normal clay a good substrate for an aquarium?
<Don't know; never tried it! Lime-free sand is ideal for Black Ghosts, while gravel works okay if needs be. So long as you aren't too fussy about the types of plants, putting them into the gravel, and then inserting fertiliser pellets every month or so, will result in adequate plant growth.
Sometimes even better! Vallisneria for example couldn't care less.>
i wanted to go with simple plants like Anubias and didn't want to spend a lot on ADA, unnecessarily.
<If you grow low-light plants like Anubias and Java Fern, avoid expensive plant-friendly substrates. The Anubias and ferns won't use them, getting nutrients from the water, but algae will take the nutrients instead!>
Will a slight murky water during water changes affect the fish in any way ?
<Black Ghosts don't mind a bit of cloudiness.>
Thank you so much again, Neale. Your help is much appreciated.
<Welcome! Neale.>

Black Ghost... conspec. comp.     4/18/16
Hi i have my BG 2 years now, he or she is like 8 inches now, my question can i add another one to the tank with my BG or not? and if yes how old or measure needs to have to be tolerant to each other? thanks for any info..Eddie Rodriguez ;-)
<Not likely a good idea. Read here:
Bob Fenner>
re: Black Ghost... Now green algae; not using WWM    4/18/16

Ok perfect, that means no....thanks...also do you know if it's OK that green algae I think it is growing on the glass tank, so i cleaned but is hard to get it out and grows again don't know what to do to clean it or if is ok to have it?
<Please learn to/use WWM; as some 30,000 others do daily... the search tool, indices....
READ here: http://www.wetwebmedia.com/FWSubWebIndex/fwalgcontrol.htm
and the files linked above>
And if you can tell me what other fishes I can add to the tank that he is not going to be stressful, I know they has to be bigger than him or her but I mean what kinds? Thank you so much for responding and sorry to bother :-)
<.... read where I last referred you. BobF>

Sternarchus albifrons tankmates/comp.        1/16/16
Hi! I just got myself a new tank around a month ago and I am starting to look at fish to put in it. My number one choice is a black ghost knife fish and I have many hiding places and a big tank. I have been looking up what tankmates are best for the BGK but I keep getting a bunch of different answers.
<Need to be peaceful... not too small, tasty, and not too big and aggressive>
I have one site saying tetras and then another site saying to not put in tetras. I was thinking of maybe some dwarf cichlids, clown loach, Bolivian rams, and maybe some catfish.
<Mmm; well; not too many or large Loaches or Catfishes... as the BGK spends most of its time on the bottom... not a great competitor for food>
I cant get any straight answers and I know this is one of the websites I do trust. I also have some guppies in the tank right now to help build up algae and things like that and then I am moving the guppies back into their own tank once i get my knifefish.
<Umm; DO read here: http://wetwebmedia.com/FWSubWebIndex/bgkcomp.htm
and the linked files above for background. Bob Fenner>
Apteronotus; tankmates /Neale's input       1/19/16
Hi! I just got myself a new tank around a month ago and I am starting to look at fish to put in it. My number one choice is a black ghost knife fish and I have many hiding places and a big tank. I have been looking up what tankmates are best for the BGK but I keep getting a bunch of different answers. I have one site saying tetras and then another site saying to not put in tetras. I was thinking of maybe some dwarf cichlids, clown loach, Bolivian rams, and maybe some catfish. I cant get any straight answers and I know this is one of the websites I do trust. I also have some guppies in the tank right now to help build up algae and things like that and then I am moving the guppies back into their own tank once i get my knifefish.
<Black Ghost Knifefish inhabit dark areas around waterfalls, rapids and riffles. They like a decent current, water that isn't too hard, lots of rocks, and some overhead shade or at least subdued lighting. If you can choose species that aren't bite-sized that want the same thing, tankmates aren't hard to choose. From South America, most of the tetras can work (avoid nippy species) with things like X-Ray Tetras being ideal general purpose tetras that require no further fuss (they're very hardy and
peaceful). Bolivian Rams would be good too, but will compete for food, eating the same thing: frozen bloodworms and other tiny invertebrates. So I'd recommend getting the BGK in and settled, feeding well, and obviously growing before you add the cichlids. Finally, so far as catfish go, choose species that won't compete for food. A small Loricariid such as Ancistrus or the smaller Panaque (like Panaque maccus) would be obvious choices, but Whiptails would be superb companions too. Corydoras would compete for food, so I'd skip them. Make sense? Cheers, Neale.>

Video of BGK      10/29/15
Here's another longer video. Hope it helps, i had to add it to DropBox as its too big to email
Thanks again
<See this. B>
BGK - hole in side of belly      10/29/15
Hi hun,
Firstly I would like to say thank you for all the amazing info on your website about BGK'S. You are one of very few sites that will help with these fish and I have learned a lot about what they need from you.
I have had this tank about 15 month now and the BGK'S about 7 month. They are in a 120lt corner tank with not many other fish. (I know this isn't big enough for adult size I'm getting a bigger tank at Xmas ��)
I do a 45lt water change/gravel/filter clean every week and a 50% every few month
Tank contains
2 BGK's (I think male 4" long & female 6" long)
<May be fighting>
2 mollies
3 guppies (won't be getting more because of BGK'S, had these since
<Am surprised the Knives haven't eaten these livebearers>
1 Pangasius catfish 3" long
<Trouble.... See WWM Re... Remove>
2 marble Pleco (male 5" & baby 2")(Were sold as clowns but their not)
<Mmm; need to know the species; this too could be an issue>

Temp 26°
PH 7.2
NO3 10ppm
NO2 0ppm
GH 180ppm or 8°d (two different test strips)
KH 60ppm or 6°d (two different test strips
CL2 0
Tank has two airstones and strong filter which I have positioned at the top of the tank to create a small waterfall/current for the BGK'S. Lighting is 9am till 9pm and its a dim blue spectrum bulb. They have 3 ceramic pots, 3 coconut shells, two plastic tubes and 2 caves I made from aquarium rocks as well as some bogwood. No live/plastic plants.
Fed on frozen bloodworm & Pleco/catfish pellets. 2 cubes a day one morning and one at night after lights out.
Now to the problem...
They both settled in fine and will eat bloodworm from hand and come out in the day. They get along fine together and seam to play with each other rather than fight (I may be wrong but it doesn't look nasty)
Yesterday I'd not seen the big female for a while which is unusual because I watch the tank a lot, more than TV �� she was hiding up behind the filter which she does sometimes but then I turned the lights out and she came out.
She has a 4mm hole on her left hand side just a bit further onto her belly next to her gills. Not it's not red or sore it's white ish but pretty deep and I'm not sure what it could be. Either it's stabbed itself on the bogwood or the other BGK has nipped it but the other is much smaller or its a water issue. As no new fish have been added for over a month. The last were the 2nd baby Pleco and catfish.
Now I know my water is very hard and I spoke to the LFS last week he's ordering me some peat pad that goes in and softens the water. He said its ok to use with BGK's.
<Tis so>
My question is do you think the GH could be the problem and the hole is due to stress?
<My strong bet is that the hole is due to physical trauma. Most likely the Pangasiid; but could be the others mentioned>
Apart from the hole and hiding more than usual she is fine and eating/swimming as normal. She's done a bit of
rubbing on that side but that's it. The other BGK is fine. How would you go about treatment?
<Move the Catfish... if more damage, separate the Apteronotids>
I don't want to use chemicals unless absolutely necessary but I want to help my fish ��
UPDATE - didn't send this straight away as I had no photo to send. I have just got a short video and you can just see the white 4mm-5mm hole. I did a 45lt water change/clean again and the BGK seams fine still. The hole seams to be heeling it's not as open as it was before so I am leaning more to injury than illness. I will send the video in another email now as it's too
big to add to this (stupid phone)
Thank you in advance for any reply
Sammie xx
<DO be a keen observer here.... some one in your system is beating on this fish. Bob Fenner>
re: BGK - hole in side of belly.... Pangasius incomp....       10/30/15

Thank you for the quick response hun. Will have a look about the catfish now didn't think there would be an issue with the two together
<Do you have any idea of how large and aggressive that swai cat gets? Please, READ>
but as I'm getting a larger tank soon I'll have space to separate them. I watch the tank a lot so ill turn the lights off and see how they are in the dark.
Everything seams to leave the BGK'S alone because if they don't they'll get nipped. Even the big marble Pleco (Colin) unless he's stabbed it with a fin.
What tank mates would you recommend with BGK'S?
<.... this is also archived on WWM>
Obviously bigger fish to avoid bullying. The BGK at 6" is the biggest in the tank but the 5" marble is stocky.
Someone else said I was lucky they hadn't eaten the 3 guppies, they've had a few small ones but these 3 keep away somehow. I'll move them to my other tank ��
Thanks again
<W. B>

Black Ghost Knife Fish      9/5/15
Hello! I have a 150 gallon aquarium, and I bought a black ghost knife fish back in November of last year. It is around 7 inches by now, and hasn't had any problems with any fish (that I have seen) thus far. However, I noticed today that the end of the "snout" is gone. It looks like it was chewed off.
<Likely has>
It is very fleshy and strands of tissue are floating off from his face. I don't know who could be doing this. I have a rainbow shark, two algae eaters,
<.... Chinese? As in Gyrinocheilus? These or the shark minnow could be culprits. Search/READ on WWM re
some mollies and platies, blind cave fish, a plecostomus, and two smaller angelfish. I haven't added any fish in a few weeks. Is there anything I can do to correct this problem?
<Have to separate the Knife, treat it for bacterial/fungus issue. Bob Fenner>
Thank you! Jeremy

Ghost Knife issue... hlth. concern        6/10/15
Hoping you can help.
<Me too>
I have a 28cm ghost knife who is around 5 years old living in my 250 litre tank with several discus fish and angels and a few cat fish cleaners. In the recent 3 months my ghosty has shown several like blood spots on his tail and now has a few more initially I presumed that my sucker fish were sucking algae off him and therefore creating blood type blisters but it is getting worse.
Any idea's on what it is and how to treat?
<I concur re your guess that this fish is likely being traumatized. What species of catfish are present? Does you Ghost have a cave/place of its own? Is this near where the Discus, Angels hang out? Bob Fenner>
Re: Ghost Knife issue       6/10/15

Dear Bob
Yes my Ghost does have many places to hang out and hide as the tank was set up mainly for him and my discus and the other fishies are 'add ins'.
<Ah good>
The cat fish are bristle nose but I am starting to think that it is possibly my 5 loaches doing it as they are the golden sucking loaches.
<Well; may be the loaches, not strange that these should go after an Apteronotid... is it possible that some element of the decor (sea shell, sharp rock) has cut into the knife?>
Your help is appreciated.
<Glad to assist. Bob Fenner>

BGK care and compatibility questions     3/13/13
Hi Crew.  Thanks for all you do for the hobby.
<A pleasure to aid (educate, inspire) others; as you know>
I've been keeping some fresh and mostly saltwater (only fresh these days) for 25 years, and I've always wanted a black ghost knife--a neighbor had a very tame one when I was quite young, and I loved it.  But I never felt I had an appropriate tank for one; I've never had a large enough freshwater tank before, and never a tank with appropriate tankmates.  Now I think I might.  I've read through the FAQ's on BGK's, and found some answers, but not everything I need to know.
First, because I know everything depends on it, let me tell you about the tank: it's a 150G (long, not high--I have one of those, too!), using a Fluval FX5 for primary filtration, assisted by a HOT magnum just for water polishing and carbon, and 4x96w 6500K power compacts for light.   The tank is pretty heavily planted, mostly several varieties of swords and Anubias, and some java fern, accented with pieces of driftwood.  Water parameters are 0 ammonia, 0 nitrite, nitrates 15-20, ph is around 6.4, and temp is 80 F.  The tank was converted back to fresh water 2 1/2 years ago.  I intended it to be a discus tank, but my first attempt at discus keeping was not successful, and I gave the surviving discus to someone who could care for them properly.  (The discus weren't eating well--they seemed unable to "catch" the food in the tank.  I'm now given to understand the problem was probably too much current from the FX5.)  The tank's current occupants were mostly selected with discus' warm, soft water conditions in mind: a large school of cardinal tetras, a pearl gourami, Bristlenose Plecos (which have been mating!), 8 Otocinclus cats, and four pairs of blue rams.  I also added three clown loaches about a year ago to take care of a huge snail problem that came in with the plants.  They seem to be doing well, the largest has grown to about 5", with the other two more like 3".  Most recently, I added 6 angelfish--a consolation for not keeping discus. 
Tonight, it occurred to me that the time might be right for a black ghost, or perhaps two.  I know they would eat the tetras when they get big enough, but the tetras have started to die off, apparently from old age--their tails get more and more hooked downwards, their colors begin to dim, and eventually, over the course of weeks, they get thin and die.  At first, I thought it was a disease, but now I don't think so.  They're over two years old, and I think they've just reached the end of their lifespan.  I don't plan to replace them--at least not with more small tetras.  Perhaps some Von Rio's?
<A good choice here... or (for me) Bleeding Hearts, other Hyphessobrycons>
So my first question is compatibility.  Do you see anything that would be a real problem?
<Mmm, no. Just care to make sure the Knife is getting food amongst so many competing fishes, in such a large setting>
 I was somewhat concerned about the loaches and the rams, but I've never seen the loaches act aggressively towards each other or anyone else, and the rams mostly keep to themselves, really.  I thought that with the high plant density, the BGK would be able to find a nice quiet nook in which to be happy.
 My second question concerns keeping BGK's together.  I know that they get big, and are generally a one-per-tank fish, but a couple of times in the FAQ's crew members commented that two might be kept together if the tank was large enough--but no one ever said how large is large enough!  What about a 150?  If I started with two 4" BGK's introduced at the same time, does that stand a reasonable chance of working?
<Two would make for a more interesting, interactive display. I give you good odds that a couple would learn to get along in this setting>
Thanks in advance for your help.
<Welcome. Bob Fenner>

BGK ninja    2/12/13
Hello my fine fishy family,
  I recently wrote to you about stocking my 90 gallon tank around a black ghost knife fish. While I didn't go by the list precisely I tried to find a variety of fish that would fit the fast moving, soft water of the ghost knife. So right now I have one BGK, 10 Banded Rainbowfish (Melanotaenia trifasciata) (the largest being 4 inches and the smallest 2 1/2 inches) and 12 Longfin zebra danios. I figured to myself in a year or two the BGK would be able to fit the danios in his mouth but they would have probably died of old age anyway. I did not count on the BGK being an eyeball plucker though.
<Yikes; yes>
Of course now that I Google those exact words I see its more common than I thought. Even so if I had know I probably would have gotten them anyway because they're pretty fast little things anyway. Not fast enough. Of course they stick their head right into the lions den as it were. The 2 danios this has happened to, are doing surprisingly well for being so terribly maimed. My question then is several fold. Do I take out the 2 danios and put them into the quarantine tank where I currently have hatchets and Cory cats waiting to go into the display tank?
<I would not move the Danios... their eyes will not regenerate...>
(Qt tank is 20
gallon long) Do I take a few more danios with them so they don't start to bully the others because they're in a small group? 
<You could if you wanted>
Do I take out all the
danios and buy and new tank for them?
<If you'd like them to live a quality life, yes>
Do I take the rainbows out too?
<These are likely fast and smart enough to avoid the Danio's fate>
Should everyone (except for the BGK) go in a brand new 40 gallon (after cycling) and I just have to find large passive tank mates for the BGK?
<Again, this option is up to you>
Info that you will probably find relevant. The display tank is ammonia 0 Nitrites 0 Nitrates 20. Temp is 75. I feed the BGK blood worms and brine shrimp. Maybe if I move to superworms he would stop going for the eyes?
really at a loss here. Thank you all for your wisdom and patience!
PS I do fast them all once a week. Could that be part of the issue?
<Not really... the fasting is a good practice. Bob Fenner>

BGK Compatibility    11/6/12
I have a 90 gallon tank with 2 adult angelfish, 4 juvenile discus, 2 adult parrot cichlids,
<These may turn on the other Cichlids here>
and a very tiny algae eater (just bought).
<What species?>

We have a variety of plants, a large piece of driftwood, and looking for another shipwreck/pipe/vase type of decoration to add. Would a black ghost knife fish work in this set-up?
<Mmm, not really... too hard to feed w/ what you already have here>
What types of fish do they/don't they get along with? I tried reading your compatibility FAQ and found a variety of answers for other species.
<Read here: http://wetwebmedia.com/FWSubWebIndex/bgkcomp.htm
I figured I'd ask about my specific set-up. Looking forward to hearing back! Thanks.
<Welcome. Bob Fenner>

Stocking a 90 gallon, FW w/ Blk. Ghost      7/29/12
Howdy all! Thank you so much for all the hard work you do by keeping us informed. I am currently fishless cycling a 90 gallon tank and am trying to make final decisions about who gets to go on in. The fish that all others revolve around, the centerpiece if you will, is a black ghost knife.
<I see. Now, remember this species comes from fast-flowing, well-oxygenated, not-too-warm waters around waterfalls and riffles. So you want species that enjoy current and don't mind turbulence. BGKs are easy to keep when small, but become steadily more difficult to maintain as they age, so what you don't want are fish that will respond badly to extra powerheads or other sources of water current. Equally important is the large size of adult BGKs; even if they aren't especially predatory, they could scare small, nervous fish. Conversely, BGKs are very sensitive to nippy and aggressive fish, so tankmates should be robust but placid.>
The others I'm thinking about going with it are 5 Denisoni Barb (Puntius denisonii),
<An excellent choice. While Puntius denisonii do prefer cool water, 15-25 C, at 24-25 C they'd be good companions for BGKs.>
1 African Butterfly Fish (Pantodon buchholzi),
<A bad choice; comes from still water and dislikes current.>
5 glass catfish (Kryptopterus minor),
<Doesn't like very strong water currents either, but if there's a gentle area in the tank, it might do okay.>
and here's where the list gets more in the air 5 silver hatchets (Gasteropelecus sternicla),
1 female golden gourami (Trichogaster trichopterus), 1 female blue gourami (Trichogaster trichopterus), (Not sure if 1 would be better or 3)
<Gouramis prefer still water, so not a good choice.>
and finally I also really enjoy the Leopard Bushfish (Ctenopoma acutirostre).
I wasn't really considering the gouramis until recently because my husband and I went to the fish store together and he said he liked the fish but the tank seemed to be lacking in color.  Anyway can you advise me as to which mix works well? The two I like best are the ghost knife and the Denisoni.
The water perimeters seem fairly close in range, but I'm worried about those gouramis and if the butterfly fish will bother the hatchets. Not to mention I'd rather not overstock the tank in general.  If the gourami isn't a good match what other colorful fish might you recommend? Thanks so much!
<Do look at fish from the same "flowing stream" environment as Apteronotus albifrons; for example Corydoras catfish, certain dwarf cichlids (Nanochromis, Steatocranus), most Barbs and Danios (look at the bigger species, which can be gorgeous), or Barilius spp "Hillstream Trout" if you don't keep the tank too warm, even Swordtails though these do prefer hard water so may not be ideal. If you're up for a challenge, Geophagine cichlids could work really well, many are quite colourful (e.g., Satanoperca leucosticta or the excellent Geophagus altifrons) though they are sensitive to water quality, especially nitrate levels above 20 mg/l, but then so are BGKs. Cheers, Neale.>

Black ghost knife fish hurt bottom fin and won't eat... Nutr. and in w/ incomp. tankmates    2/29/12
Hi, I have had my black ghost knife fish for over a year and a half now in a 60gallon tank with 2 Severums, a jewel,
<Mmm, not really compatible w/ these cichlids... and the Severums will need this volume plus for themselves>

 a Bala shark, a cribnasis, a Pleco, and 3 rainbow fish. My knife is about 7.5 inches long and eats a variety of frozen and freeze dried bloodworms.
<See WWM re these sewer fly larvae. Implicated in disease>

She has had a few issues in the past with cuts in her pectoral fins,
<? From what?>

but she has been fine for a while. Recently however she has stopped eating for over week now, and she isn't hiding in her cave anymore, instead she's just laying along the side of the tank. her entire bottom fin is all severed like a feather.
<... see above. Needs to be moved elsewhere, and fed better foods. See WWM re: http://www.wetwebmedia.com/FWSubWebIndex/bgkfdg.htm
and the linked files above>
 The end of her tail is also red and bloody, and she has a Slit on the top of her. Right before the white in her tail. It seems like this happened over night.. What do I do?
Thanks, Aubrey Theisen
<... read, act. Bob Fenner>

Black Ghost Knife and Discus, comp.    1/25/12
First I would like to thank you for the wealth of knowledge you have on your site.
It has helped me to avoid several potential disasters with my tank.
I do have a question though that I can't seem to find a definitive answer for on your site.
I have a 90 gallon planted aquarium with 7 Discus and a BGK about 6 inches.
Most of the Discus are  juveniles with the largest measuring about 4 inches.
PH 6.8, ammonia 0, Nitrites 0 and nitrates stay around 10 to 20. I do 50% water changes once a week and sometimes do a 20% midweek when I have time.
The temp stays at 83.5. I have a Fluval 406 with foam carbon peat and bio media, an Eheim 2217 with only foam and biomedia, and an Emperor 400 with active carbon in the refillable cartridges w/ bio wheel (am I over doing it with the filtration).
Currently the only issue I see is I do not have a quarantine, or hospital tank due to the fact my wife almost killed me when I got back into the hobby/obsession of fish keeping again.
All of my fish seem healthy now and the tank has been running for 6 months without issue thanks in part to the knowledge I have gained about Ghost Knives from your site. From the info I have read on your site about BGK and there sensitivity to medication, I would like to go ahead and order and have on hand medication  for any outbreaks of Ick
<Just treat w/ raised temperature>
or other parasites and or diseases that may pop up.
 I don't plan on adding any additional livestock other than a snail or two and maybe some ghost shrimp. I have heard about the need to deworm Discus when feeding them bloodworms
<Limit or eliminate these sewer fly larvae. Troubles nowadays>
 and other frozen high protein foods. Can you tell me what you would recommend for treating Ick or other parasites and diseases, and deworming the discus with the BGK also residing in the tank.
<I would not treat in the tank period, and not now anyway. So; "none of the above">
I find that moving a fish to another tank to medicate it in the past has caused further stress on the animal and never ended well.
Also what are your thoughts on adding salt to a tank with Discus and BGKs?
<I wouldn't>
Also your thoughts on BGKs and Discus as tank mates?
<Can work...>
Thanks in advance for any light you can shine on this for me.
Jason in Kentucky
<Welcome, Bob in Ca.>

my fish  9/5.5/11
Well I have 2 Dinosaur bichirs, 2 gourmi's, a Pleco, a red tailed shark, 2 Bala sharks,
<Will get much larger...>
and a Africa brown knifefish. I have a 55 gallon tank with plenty of hiding holes. Will a black ghost knife be compatible?
<No; issues w/ your other Knife, feeding competition... Read here:
Also how do I introduce hand feeding to my Bichirs and Knife fish?
<Use the search tool at the bottom left corner of any page... add the term "freshwater" to your string. Bob Fenner>
Please send me the answers to my email which is... <Done!>
Thank you so much

Black Ghost Knife and Oscar tankmates...  7/16/11
This morning I was conducting my daily headcount in my aquarium and was missing my Ghost Knife. Apparently at some point during the night he jumped out of the aquarium and I found him on the floor.
<Happens. Turns out there are very few fishes, mobile aquatic organisms that can leave via the top>
He's never been prone to jumping and the lid was shut all night. The only thing I can think of is that he jumped out the back opening but that's a pretty tight fit. He was about 10-12 inches long and would have had to have been trying really hard to get out of that crack. Also, I recently moved and with the new stand, did not have enough air hose to hook up the pump. I have a Marineland canister filter rated for 100 gallons and 2 other powerheads in the tank. Am I wrong in thinking that these elements alone, without the air pump would cause enough surface disruption to provide oxygen to these fish?
<Mmm, should... DO can be measured...>
The Oscar is now approx 8-10 inches long now and the Plec about 5.
<I would not keep an Oscar and Apteronotid in the same system>
Also with these fish still in the tank is there anything you would recommend adding in there?
<Please read here: http://wetwebmedia.com/FWSubWebIndex/oscarcompfaqs.htm
I would like to keep another Black Ghost Knife but if I got a small one I don't see him doing well in that environment.
<Agreed. The Oscar is too likely to damage the BGK, eat all foods>
I was also thinking of setting up a different tank and putting a BGK and a Xenomystus Nigri in it with some live plants. Does this sound like a good system as far as water conditions and behavior?
<Mmm, maybe... a bit boring for me... I'd add some fish with movement, colour... Perhaps some Melanotaeniids/Rainbows>
Thank you for your time,
<Welcome. Bob Fenner>

Can a community tank include Black Ghost Knife & Clown Loaches?   5/5/11
Hi team,
Today sadly I had to euthanise my large Oranda Wolfgang, I'd had him since he was a tiny baby, I'm not sure what happened to him, his Wen grew so big it covered his eyes but he was still happy, he was always a little top-heavy
A couple of months ago he just started lying on his side & not moving much, I thought (seeing all the water parameters were fine) that it was just because he couldn't see & was unsure of what to do, he'd still right himself to eat & swim around the bottom. The past week he's been really bad, barely moving except for dinner & he was starting to get thin & get pressure sores on his sides from lying down, so sadly, the time came, he's now buried under the hibiscus with Yolky his longtime Ranchu friend
What I was wondering now was, I have a 4' x 2' x 2' tank that's just got a peppermint Bristlenose in it & so I was wondering what to put in the tank.
<Many possibilities>
When I first got into fish keeping about 25 years ago my Mum bought me a Black Ghost Knife fish, he was only tiny when she got him & over the 8 years that I had him, he grew to over a foot in length. Poor Moo though taught me the valuable lesson of having a back-up heater in the tank as one day in winter he started fitting & it turned out that the tank was cold as the heater had blown up. It was such a loss to fish-kind.
We then went onto the community type tank with clown loaches, Corys, glass cats, various large tetras & a butterfly fish.
I do like the clown loaches, they've got a lot of personality & I would dearly love to have another black ghost knife. Would they co-exist?
<Mmm, can, yes>
I was thinking 1 black ghost knife & maybe 6 clown loaches, maybe some sort of Corys, the glass cats & what about Congo tetras?
<These two would add colour, motion to the mid-water area>
I know that I can't have small fish in with the ghost knife (Moo ate Mum's beautiful guppies when they had to move into his tank for awhile) & I vaguely remember that you can't have Plecos with knife fish but would those others mentioned be ok?
<Yes. Do see/read on WWM re the water quality, nutritional needs of all you list here>
Also, what about salt in the water?
<Not a good idea generally. Read here:
I always used to put some conditioning salts in with Wolfgang & Yolky, it was a mix of pool salt, Epsom salts, bicarb & Melafix as well as Prime & Stability.
<Shortened their life times>
It's been awhile since I've had tropical fish as after I lost Moo I went into marine fish for about a decade but then swapped to the Orandas 'cause I thought that they would be easier to look after (give me back my marine tanks any day!)
Sorry about the long winded waffle but I really wasn't sure & I would like to start off on the right foot again.
Also, in terms of cleaning the tank out, it's warm anyway as Wolfgang liked it a little warmer, should I do a full water change or just a % & clean out the filter? It should be good bacteria wise as it's been running for years.
<I would change out most all, vacuuming the gravel>
Thanks in advance for any advice & thanks also for reading.
<And you, Bob Fenner>

BGK tankmates, not turtles   4/16/11
Hello WWM Team!!
<Howdy Hank>
Hank here, I am a longtime herp-hobbyist and, I recently discovered the world of aquaria! Let me begin by saying your site is definitely one of the top three sites (regarding usefulness of both Herps, and Ichs) I have scoured, so far. your BGK area has answered most of my questions about BGKs.
I recently added (4/14/11) a BGK, "Little Ninja," to my 28g bow-front tank that has been in use a little less than a month. Before Little Ninja was added the inhabitants included a hatchling YBS (c. 1 month old at most, c. 2" nose to tail-tip "Phinn"),
<Mmm, not compatible>
a Pleco (specific species unknown, as I am weary of trusting LFS in I.D.ing them properly, c. 1 1/2-2", ), and a female Golden Gourami (c. 2 1/2-3", "Wanda"). These will be the ONLY inhabitants besides two or three emerald Corydoras. Thanks to you guys I am well aware of the *possible *size of the BGK and, hopefully, he will get as large as possible.
<Not here, no. This volume is too small... and the shape... would be better to be long, flat>
I do not want his growth stunting so in August I will be upgrading to a much larger tank size (at least 75g and will be the only inhabitant besides the Corydoras and another Pleco [hopefully an albino Sailfin Bristlenose]).
<Oh! I'd add some other "more open behavior" life here>
My question is are these tankmates SAFE for my lil' Ninja until his upgrade, regarding both bio-load and the Gourami ( two reptile filters)?
<Not really, no>
And, is the dechlorinator I use for the turtle safe for him (it doesn't have copper in the ingredients, but I'm not sure about the other ingredients, it's also supposed to promote healthy slime coat for amphibians)?
<Is likely fine>
He currently lives in a ship aerator in my sand-bottom tank, next-door to Wanda who has taken up in the hollow root system from my LFS.
He has been very active, as active as any healthy fish should and, he immediately began going in and out of his ship within hours of introduction, and began investigating the tank, and eating(with the light on!!). Wanda doesn't hog food, they share blood worms, and tropical flakes.
Wanda has been very nice so far, she has a history of non-violence unless forced (she use to be in another tank exactly like the aforementioned[reg. size] with a Pleco[1 1/2-2"], male golden Gourami "Napoleon" 2-3", six bream fry( I caught and added these as feeder for the Eastern Painted Turtle "Rembrandt" or, "Remi" c. 5 mo. c. 6" nose-tail [four have disappeared!]) and Napoleon bullied her to the point they literally "locked jaws" until I lightly touched Wanda, and they separated. I IMMEDIATELY separated them realizing there was probably too much fish for that tank. Once separated I temporarily housed Wanda with a 2yo male YBS who also paid her no attention, obviously(although she would pick the algae off of him(I caught him in the wild last week sometime), as well as using him for a blind! Now, I can hand feed both Wanda and Napoleon flake food! And I cant wait till Lil' Ninja does the same!
Phinn is still a little skittish but has gotten to the point I am familiar to him. He isn't enticed by any of the fish considering they are all bigger than him, except for the Pleco, and doesn't chase any either. I feed both turtles in separate feeder tanks(with the exception of the four missing bream fry from Remi's tank), and usually leave them there for at least an hour so they can defecate in there rather than their aquariums to reduce detritus, and water fouling a.m.a.p., ideally to reduce clean-up a.m.a.p.
Any advice, suggestions, or questions are greatly appreciated and I can't wait to hear back from you guys!
<I'd separate this little turtle... place it elsewhere>
Thank you so much for what you guys do,
<And welcome to the wonderful world of aquariums! Bob Fenner>
Re: BGK tankmates   - 4/16/2011

>> Hello again team WWM! And, thank you, Bob!
I apologize. I accidentally sent that email before typing the rest! Would a 55g long be good for Lil' Ninja until August? And, what tankmates do you guys suggest? The hatchling turt will remain in the 28g bow-front until august for sure, depending on his size at that time I will see about a tank upgrade...
Again, I apologize! The same thing happened again!
Anyway, this morning I removed Remi(the 6" nose-tail E. painted) from his current tank because I
caught him, for the first time EVER in the months I've had him, chasing and nipping the Plec in there (Gggrrrrrr, I was mad but, I should have known better!!).The Plec is fast enough to escape Remi but, Remi sneaked up on him. So, in the 28g bow-front formerly housing Remi, Napoleon(juvenile male golden Gourami, and the Plec it is just the Plec and Napoleon, lightly planted in the corners with fake plants( I am in no way ready for real plants yet!). Do you have any tankmate suggestions for this one as well?
<Do read here please: http://wetwebmedia.com/FWSubWebIndex/bgkcomp.htm
and the linked FAQs file above re Stocking/Selection, and the same for the other species you're housing here... On WWM. The search tool is likely your best route/tool here>
Thanks again,
<Welcome. BobF>
Re: BGK tankmates   - 4/16/2011
Hey guys,
My BGK is still acting healthy and eating his blood worms and flakes.
However, I noticed earlier today he has a white spot on his underside about where his fins and gills connect.
<May be this fish's anus...>
From what I've both seen and read, so far, the stripes on his head and tail are the only markings(if it turns out this is just another color mark I'm delighted!! Otherwise...) Is this a normal color mark or, the beginning of something like Ich or, another parasitic/bacterial infection? I am about to move him into his own 30 gallon temporary Tupperware bc I failed to quarantine him before introducing him to his current tank(sorry :-/ ).
<I would not do this. Quarantine is too late>
Thanks Team!
Re: BGK tankmates   - 4/16/2011
Thank you, luckily I was going to cycle the Qtank for several hours before adding BGK and still hadn't added him when I received your response. The whit spot on the bottom IS the anus. But, just in case I will continue to keep an eye on him!!
As always thanks for your passion and information!
<Always welcome. BobF>

Siamensis and Black Ghost Knife Fish, incomp.  4/7/2011
<Hi there>
I have a 60 gallon tank with 4 Siamensis (3 inches), an Angel, Pleco, a few Rasboras and Rummies, and a 14 inch Black Ghost Knife Fish that I've raised from 3 inches.
I've had the Black Ghost about 5 years; the Siamensis I got about a year ago.
Everyone seemed to be getting along fine until the other day I noticed the Black Ghost had a wound at the underside of the base of his tail. At first I thought he might have caught it on some driftwood, but later I noticed that the flesh was actually gone down to the fine bones in his fin. Then today, I caught my Siamensis nibbling on him at the wound site. In fact, they would not leave him alone, even though he kept trying to get away. I isolated him immediately, but my question is, do you think the Siamensis might have caused the wound in the first place, or were they merely taking advantage of the opportunity for fresh sushi?
<Can't say, but I know of other cases of SAEs doing such nibbling>
From everything I've read, they are not aggressive towards other fish in a community tank. I've double-checked to make sure they are indeed true Siamese Algae Eaters, and not one of the false variety, which, I understand, can be aggressive. They are definitely the true Crossocheilus siamensis, so I'm puzzled.
I'm definitely keeping Squiggles (the Black Ghost) in quarantine until he is healed, but I'm concerned about putting him back in the tank with the Siamensis, especially now that they've had a taste. Your thoughts?
<I would be (unfortunately) separating these fishes. Bob Fenner>
Jaz Taylor

Black ghost knife fish, incomp.  10/23/10
<Hello Craig>
I have 2 BGK fish in a 50gal tank
<Mmm, I would not put two of these Apteronotids in such a system...>
along with 3 clown loaches. There are 2 PVC pipes that each of the BGK fish hide in and another cave that the clowns play around in.
The water conditions are normal.
<You should read re the range of "normal" cond.s for both these species...>
I clean the tank with a 60% water change about once a month and do 20%-30% water changes along with cleaning the filter every 2 weeks.
I usually add a stress coat or something similar to the tank after a large water change. Of late I have noticed the BGK fish have rips in the anal fin. what could be the reason??
<Fighting amongst the two>
The tank is around 6 yrs old now and the bigger BGK has been there since the beginning.
<I'd trade out, sell/give away the other one; stat.>
Thank you.
Craig Dsouza
<Bob Fenner>

Black Ghost Knife and Oscar tankmates. Holy incomp. Batman!  02/14/10
I have a 55 gallon tank with a 3" Albino Tiger Oscar, a 5" Black Ghost Knife and a 3" common Pleco.
<Overstocked already.>
I would like to get some other fish to keep with them. I would like to know what types of fish my tank would accommodate with respect to a) bioload, and b) temperament.
<Nope. Even by itself, the Plec is going to put a really heavy load on the aquarium. Add an Oscar, and things get dirty pretty fast. An adult Black Ghost as well? No way.>
I was thinking maybe even an Electric Blue Jack Dempsey because I read that the Electric Blue was a genetic defect that generally made for a less aggressive and smaller variety than the standard Dempsey.
<Heard rumours about its lesser aggression too, but frankly, this is still a crashingly bad choice for this tank. Central American cichlids have very specific requirements, and mix poorly with South American ones.>
I wanted to confirm that assumption before I bought one. My Oscar is a very passive fish, however, I do understand that they get more territorial as they mature. Would the EBJD be a suitable tankmate?
<No, it wouldn't.>
This would really be my preferred option as I like the more sturdy, larger fish. Is there a breed of cichlids that I could maybe put another 3-4 fish in this tank peacefully? I know you may not like it for it's size, but I will be upgrading to a large canister filter soon and would really like to have a few, more interesting fish.
<I think you need to review the needs of the fish you have. An adult Black Ghost is upwards of 50 cm/20 inches in length, and extremely sensitive to poor water quality. Most folks fail to keep them alive for more than a couple of years. When was the last time you saw a full grown specimen?>
As for dither fish; what would you recommend? I've read where you have advised Clown Loaches and Angel fish, but I would like something a little more exotic. Silver Dollars are okay but I've read that they can be a little nippy. Could a few Bala Sharks or Serpae Tetras cohabitate with the fish I already have?
<Serpae tetras are FAR too nippy to mix with any of these fish.>
Are there any freshwater puffer fish that would survive with these fish?
<Repeat after me: puffers aren't community fish, puffers aren't community fish. By all means keep a puffer, but in its own tank. South American puffers and Carinotetraodon irrubesco are the two species that might be considered, being relatively peaceful. But SAPs are too nippy to keep with Oscars, and adult Oscars would simply view them as a potentially edible nuisance. As for Carinotetraodon irrubesco, this species would also be Oscar food, even though it isn't especially nippy.>
Thanks in advance for the help. It's very much appreciated.

African Butterfly fish Compatibility 1/25/2009
First of all, thank you for the superb information you have on your site!
I have a well established 125 gallon (US) tank with an average Ph (I haven't tested it in a while, but everyone seems to tolerate it), housing 6 small silver dollars, a 4 inch Black ghost Knife, a 2 inch Leopard Ctenopoma, an 8-9 Rhino Pleco, two Botia Kubotai, and two Kuhli loaches (I would move them to a tank where they were less bite sized, but catching them in my well planted tank full of driftwood is near impossible). They usually all stay near the bottom and middle of the tank.
Recently, while browsing my local fish store, I noticed that they had an African butterfly fish in one of their tanks. I'm wondering if the Butterfly fish would be suitable for my tank.
<Possibly, but Silver Dollars may harass it. Pantodon buchholzi is also somewhat fussy about its habitat. It prefers shady tanks and will normally hang about at the surface where the flow of water is minimal. Tall or floating plants are a must.>
I feed the tank flake, shrimp pellets and "bottom feeder wafers" in the day, and at night they get a very small bit of flake and frozen bloodworms (I plan to get live brine shrimp for the Knife when my LFS has them in-stock). I have some floating plants that provide shade (and some security for the Ctenopoma) that cover about 1/4 of the surface of my tank.
My tank lid is glass and relatively heavy, so jumping should not be a problem. Plus, if I get the Butterfly fish, should I get them in a pair?
<They are mutually territorial and so far as I know, don't form stable pairs. Allow about a square foot of space per specimen, assuming each square food has one suitable resting place.>
Thanks! -Jack.
<Cheers, Neale.>
Re: African Butterfly fish Compatibility
First of all, thank you for your quick response. I don't think the silver dollars are a problem for the Butterfly fish, since they tend to be a bit timid, swimming in and out of the driftwood and low plants, and as far as I know, haven't harassed anyone.
As I said in my last message, I have a large mass of floating plants at the top of my tank, which should be perfect for Pantodon buchholzi.
The water in my tank is relatively slow-moving, with the water near the sides a bit faster due to the filters.
<See, you need to be careful here: Apteronotus albifrons will not live long in a tank with limited water current. These fish come from rapids and such like habitats, and as they grow, their oxygen demands go up. (Remember,
when a fish doubles in length, its mass increases 8-fold, so its oxygen demand gets very much greater than you might imagine.)>
And, my silver dollars are only about 1-2 inches in diameter, do you think that the butterfly fish could fit it's mouth around them?
<Likely not.>
also, Do you think it would require anything else than frozen bloodworms daily and store bought crickets once or twice a week?
<Juvenile Pantodon are best fed on wingless Drosophila, easily obtained from reptile pet stores. Crickets can be a bit big for them. In any event, quarantine them first, and during that time, train them to take carnivore flake and pellets. Once they're on a staple of that sort, you're better assured good health.>
Thanks! -Jack
<Cheers, Neale.>

Re: African Butterfly fish Compatibility... and BGKs  - 1/25/10
Regarding the ghost knife and sufficient oxygen, I could add a bubbler in the tank, near (or in, if that would be better) the piece of driftwood the Knife fish resides in. Do you think adding a bubbler could supply the knife
with sufficient oxygen,
<Wouldn't be my first plan of attack. Apteronotus needs crystal clear, highly oxygenated water. Think of water splashing around rapids or a small waterfall. That's the goal here. Keep reminding yourself that most folks kill their specimens within a year or two of purchase, and you rarely ever see 15-year old specimens a full 60 cm (over 2 feet) in length. Why? Because what works for standard community fish doesn't work for Apteronotus albifrons. These are difficult fish for advanced fishkeepers.>
while at the same time not disturb the Butterfly fish? I'm pretty sure the tank is long enough so that the bubbler can be going on one end, and the other side to remain mostly undisturbed. Oh, and one final question: My Black ghost knife likes to "Play dead" during the day, and then instantaneously start moving again when the light is turned off. I assume this is normal behavior, being a highly nocturnal fish?
<Yes; indeed, they seem to like to rest on their sides.>
Thanks again! -Jack
<Cheers, Neale.>

Knife fishes... Xenomystus and BGK comp.    1/23/10
Hi guys,
It's been a long time since I've had a question for you. Everything has been going very well.
I now have a 240 gallon tank with a 6" diameter rectic sting ray, 12 inch silver Arowana, 6" Bala shark, 5 ea. 2" clown loaches, a 5" African knife, and a 5" black ghost knife. I read somewhere that it was not a good idea to
keep the two knife fish together. I'd like to hear your opinion/experience on the subject.
<These two Knifefish are very different in terms of habits, so should cohabit reasonably well, providing each had space and a suitable cave.
Apteronotus albifrons is an electric species, and yes, in captivity small groups are prone to bullying. This is common to electric fish, in part because they "jam" each other when confined in small spaces. Apteronotus albifrons may be kept singly, or else in large groups of six or more specimens. Xenomystus nigri is not an electric species (though it may well detect electrical fields generated by its prey). Although territorial, it is not nearly so aggressive as its Asian cousins in the genera Chitala and Notopterus. Those Asian knifefish really do need to be kept singly once sexually mature, the males in particular being notoriously defensive in the wild, supposedly biting at humans who wade too close to them! By contrast, Xenomystus nigri is comparatively easy going, juveniles at least being gregarious, adults territorial but not much given to tantrums if allowed space to themselves. Hope this helps. Cheers, Neale.>
Re: knife fishes 1/25/2009

Thank you!!
<Most welcome. Neale.>

The mystery of disappearing fry   1/18/10
Hi guys and gals,
You did a great job helping me deal with finicky guppies that used to drop dead on me for no apparent reason. Now Im back with another puzzle. Here is the setup: a 38G community tank thats been running for a while, complete with all necessary gadgets. The gang consists of 5 guppies, 7 mollies, 5 platys, 3 pre-adolescent clown loaches, one red-tail baby shark Seeking, and a 5 black ghost knife dont ask why, the oddball was inherited.
<This fish will of course eat baby fish, given the chance.>
I used to have a smaller tank (had to get rid of it after continuous complaints from my co-habitants) with a mesh breeder in it and this is where all of the fry from the community tank parents was hanging out.
<Do bear in mind breeding traps are somewhat less useful than you might imagine. It's often best to keep livebearers in single species tanks filled with floating plants; usually, a surprisingly good portion of the fry survive under such conditions. Traps and nets can work, but fry will jump out, and some fish will chew through the net at night (catfish and loaches especially) producing small holes through which fry can escape.>
Since the smaller tank became no more, the breeder was moved into my 38G and attached to the wall. One fine morning I woke up to find that all of the fry except two were missing. After a few vocal displays of frustration and disbelief I went on to examine the breeder which turned out to be structurally intact.
<Do remove the net, if it is a net-type trap, and review CAREFULLY.>
I pondered what could have happened for a while before falling asleep and woke up this morning to discover that one of the two survivors a lovely Dalmatian Lyretail molly fry was gone. Now all I have in there is a 4 week old guppy.
<I see.>
Needless to say, Im bothered by what have happened. The fry could not have escaped on its own.
<But they can jump.>
Its also unlikely that they were caught through the mesh walls of the breeder as those are rather stiff and the mesh is fine.
<Check for holes.>
The only possible answer is that some deviant fish jumped from the main tank into the breeder, helped itself to baby fish AND jumped back out into the main tank.
<Possible, though I admit unlikely.>
This is rather advanced thinking for aquarium fish, isnt it? And who is to blame? Im leaving the ghost out the thing cant decide on whether it can swim, let alone jumpwho else? Clown loaches?
<Can chew nets.>
They always hang out in the corner together scheming something and looking suspiciously super cuteAnyone has experienced this before?
<Yes; lost various fry when an Ancistrus catfish decided to graze algae from the net. I now don't bother with traps much, and instead use 8 gallon tanks with heaters and simple filters to rear fry, or else leave them with parents and tonnes of Indian Fern.>
<Better luck with the next batch! Neale.>

New Black ghost knife, comp., sys.    1/15/10
Hi, I have recently purchased a Black ghost knife fish, along with a Leopard Ctenopoma and six silver dollars from my LFS. They inhabit a 125 gallon (US) tank along with a (more or less) foot long rhino Pleco, two *Botia Kubotai*, a horse head loach and a Kuhli loach (simply because I couldn't catch him if my life depended on it).
<Should all work together, though Ctenopoma don't like strong water currents, whereas loaches and Apteronotus do, so some care will need to be taken in arranging water currents and resting places.>
The tank is well cycled (been around for about five years), and I perform weekly water changes of 40-50%.
I have average Ph, leaning a little bit on the harder side.
<pH and hardness are different things, so don't get them confused. In any event, this collection of fish will be fine in slightly basic, moderately hard water (i.e., around pH 7.5, 10-15 degrees dH).>
Everyone is doing quite well, and the Ctenopoma has staked out a region.
<As is their wont. They do like being close to the surface though, so tall or floating plants are very beneficial.>
At first, about five hours after purchasing the new fish, I thought the BGK was dead-- It was laying upside down halfway inside a piece of driftwood, now moving. The next morning, he's fine, and has decided to make his home in a piece of driftwood were my Botia Kubotai already have a territory (he's kicked them out, which I find pretty amusing).
<Like many electric fish, they seem to "irritate" other fish with their electric field, and so can bully them somewhat.>
My question is, do I need to feed him exclusively at night, or can I also feed him in the daytime?
<Initially at night, but once settled and tame, these fish feed willingly during the daytime.>
And can I simulate night by simply turning off the tank light and then feeding him?
<Why not try it and see?>
Also, are bloodworms a good choice for my BGK (and the Ctenopoma?).
<Within reason, yes, but they shouldn't be the only food items because they aren't terribly nutritious. Augment with black mosquito larvae, brine shrimp, chopped seafood and fish fillet, earthworms, krill, etc.>
Thanks! -Jack.
<Cheers, Neale.>
Re: New Black ghost knife   1/16/10

Water currents aren't a problem, as I have a giant floating mass of plastic plants up at the top of my tank.
I think my pH.
<It's lower-case p, capital H, i.e., pH.>
and hardness are more or less what you recommended, so that should be fine.
After observing the Botia some more, I've found that the Knife fish and the loaches have started to co-exist in the same piece of driftwood, though why is beyond me.
<May be fine. I'd add some additional, viable caves to the system though.
Loaches can be territorial, and their subocular spines can scratch their enemies. Damage to your Apteronotus should be strongly avoided, because treatments for Finrot and Fungus can easily kill these extremely sensitive fish. Very, very few specimens last more than a year in captivity through poor water quality; lack of oxygen; overheating; and exposure to copper, formalin, and other such toxins.>
I purchased a pack of bloodworms from my LFS, (though they were sold out of everything else-- I got the last package of bloodworms) and plan to feed it to them, along with a small amount of flake food, bottom feeder pellets for the loaches, earth worms from a local bait and tackle shop, and brine shrimp once my local fish store gets some in.
<Do remember to avoid freeze-dried bloodworms and concentrate on live or wet-frozen ones, if you use them more than once a week. Used to excess, these dried foods can cause constipation.>
Thanks for all of the great advice!
<Happy to help. Cheers, Neale.>
Re: New Black ghost knife
Thanks for all of the great advice!
<Happy to help.>
The bloodworms I purchased were wet-frozen, and I plan on ordering more driftwood for my tank. Everyone still seems to be getting along (except for when my massive Pleco decided that he was going to wedge himself into the
driftwood that my loaches, knife fish and Kuhli loach were currently in).
<Hmm, sounds like a grouchy catfish...>
My silver dollars seem to be hiding in the corner of the tank, though, so I'm wondering if there's anything I can do to get them out swimming around.
Do you think if I bought a few more (assuming that when they get larger, they won't be overcrowded) that they
would come out more?
<Probably, yes. Did you say you had a 125 gallon system? You should certainly keep 6-10 specimens, if that's the case. Silver Dollars also appreciate some shade, and they do tend to be nervous under bright light.>
Also, I'm pretty sure my water was a little cool for my fish (71 degrees Fahrenheit), so I purchased another heater and boosted my tank up to around 78.
<Would nudge that down very slightly, to about 25 C/77 F for optimal results. Apteronotus and most loaches come from relatively fast-flowing, oxygen-rich waters and don't like things too "stuffy".>
<Cheers, Neale.>

Black ghost knife fish and tankmates 08/26/09
hi i recently inherited some tank mates i was not expecting
<Oh dear...>
the stocking is a jack Dempsey, flag cichlid, 2 yo yo loaches a black ghost knife fish, 2x keyholes a royal Gourami and 3 silver dollars
<Hmm... a bit of a mixture there.>
they are in a 200l tank with excellent filtration 2x Fluval u4s and a Rena xp2 external
<Well, a 200 litre tank isn't really big enough for all these fish. Now, let's step through them one by one. The Jack Dempsey is an aggressive, territorial species that could easily claim this entire tank as its personal domain. While compatible with other Central American cichlids, this would usually require a somewhat larger tank, and in any case, the Central American cichlids would all be pretty boisterous and of course
requiring the same hard, alkaline water. The Flag Cichlid is, I assume, Mesonauta festivus, a lovely big (20 cm/8 inches) cichlid from South America. It's a lot like an Angelfish in terms of behaviour, and actually
mixes with them pretty well. On the other hand, it isn't aggressive enough to get along well with Central American cichlids, though I guess a female Jack Dempsey might be less aggressive than a male, so your mileage might vary on that count. Still, not a textbook combination. Your loaches (Botia almorhae) would work well with Mesonauta festivus, and given space, so should your Keyhole Cichlids, Gouramis, and Silver Dollars. The Black Ghost Knifefish will eventually need a bigger tank, though a juvenile can work
well in tanks this size. Adults get to as much as 40 cm in length, though this may take over a decade. The flip side to Black Ghost Knifefish is that they're inhabitants of fast flowing, well oxygenated water, and this isn't
necessarily what things like Flag Cichlids and Gouramis enjoy. Still, provided the turnover is somewhere between 6-8 times the volume of the tank in turnover per hour, you should be okay.>
my question is will there be any problems i should be aware of?
<The Jack Dempsey is the short-term danger, being potentially aggressive enough to damage some of these fish, perhaps all of them. Longer term, you have too many big fish, and even if you got rid of the Jack Dempsey, you'd still need a tank 50-100% larger than the one you have now. Once your bigger fish species are above the 15-20 cm/6-8 inch mark, think about either rehoming some of your fish, or else buying a bigger tank.>
what should i be monitoring?
<Short term, look for signs of fin damage and so on. Make sure all the fish are swimming happily, and not obviously hiding or cowering in corners.
Longer term, monitor nitrite and nitrate to see that filtration and aquarium size are adequate to the fish being kept, and if nitrate consistently stays above 20 mg/l, there's a good chance your cichlids will be prone to Hexamita infections. Overstocked tanks suffer acute nitrate problems, even if filtration is able to deal with the ammonia and nitrite.>
the cichlids were the ones i inherited! thanks in advance Eryn!
<Eryn, please do use some capital letters if you write back. We really do appreciate them! Cheers, Neale.>
Re: black ghost knife fish and tankmates 8/27/09

Thank you for all the info I have found it very useful. I do intend on getting another tank soon so I will spread the larger fish out! Thank you again! Note the use of capital letters! Lol!
<Glad to have helped, and thanks for using capital letters. It doesn't sound like much to you perhaps, but to other site visitors, particularly those with reading/learning difficulties, or for whom English isn't their first language, niceties such as capital letters, correct spellings, and proper use of punctuation marks make a huge difference. Cheers, Neale.>

Re: Tiger Barb is getting S shape body! & BGK comp., sys.   06/09/09
Thank you for your response. I've never heard of whirling disease, I looked it up & read some interesting info. My barb did eat well still this morning and does swim OK. At least not in circles YET, like what it said in the search for whirling. I will isolate him and see what happens for a few days and if he gets worse I will put him down if it has to come to that. Thank you much!
I do have another question if you don't mind. I have been researching info on keeping Black Ghost Knife fish. What an awesome creature! Before I do buy one I'd like to know if he would be OK in one of my tanks. I have 2 setups that are possibilities..
1- my 90 gal, setup about 3 years. Water chem..nitrate O.. nitrite O.. ammonia O..pH 7.6 Fish in tank- 3 blood parrots 1 Jack Dempsey (oldest fish in tank and as sweet as can be) 1 Raphael cat, mom Kenyi and her 2 babies, (took dad out of tank picking on fish) 2 rainbow sharks, 1 jewel, 1 Severum, 1 l Lg Danio.
<Mmm, not a good setting... the Cichlids are too likely to work the BGK woe>
2- my 55 gal setup about 2 years. Water same as above. Fish in tank - 5 Australian rainbows, 2 diamond tetra, 2 rosy barbs, 2 gold barbs,2 black skirt tetras, 2 clown loaches, 2 queen loaches, 2 Chinese algae eaters 6 coolie loaches ,This one I'm a bit concerned about the coolies to be eaten (looks like worms) unless I house them else where.
<Mmm, not by the BGK, but the larger loaches might well bother an Apteronotid too much here as well>
I do have a total of 9 fish tanks setup.
I do weekly water changes 40-50 %
<Mmm... I would limit this to about 25%... unless you're storing, checking the make-up/exchange water, it's too easy to get into trouble with source water quality variability>
& both these tanks run on Aqua clear 110 filtration. Also have extra filtration systems available if I do need to add one more. Thanks I would appreciate knowing what you think before I buy this fish. I do have a 29
bow front but not setup yet.
<I would eschew the stocking of a S. American Knifefish in these systems.
Re: Tiger Barb is getting S shape body!
Thank you, I'd rather know now then be sorry later!
<Ahh, yes... understood, and agreed! B>

Black Ghost Knife Q, comp. with loaches   4/8/09
First I want to say that I've read all the questions and responses on your BGK page. I'm in the process of setting up a 55-gallon tank, and once it is completely cycled I plan on waiting a few extra months to be sure
everything is where it should be as far as parameters and all go. Currently I have 2 tanks set up, a 30 and a 20 gallon, both heavily planted, that I've had for nearly 2 years now. I have 3 yo-yo loaches (2in long each),
and a starry night Pleco (about 2 1/2in long) in the 30, that I plan on transferring to the 55 once it's cycled and ready to go. I've read that the Pleco will only get to be 4in and the loaches no one seems sure of. I've
read variously that they will be anywhere from 4 to 8 inches long once full grown.
<Mmm, Botia almorhae grows to about a maximum of 13 cm./4 inches in the wild... yours will likely get no larger than 3" over time in this setting>
But my question is will they (the loaches and the Pleco) be good tank mates for the BGK? The loaches currently school and sleep with a pair of Cory cats, and don't bother anyone (I have 5 Danios in that tank as well and nothing else) but wasn't sure if that would change once I get them in with the knife.
<Mmm, likely so... though the loaches may be a bit more active than the Apteronotid would prefer>
One other question if I may. I originally got the yoyo's to help with a snail problem, but they are totally ignoring the snails. I've had them almost 3 weeks now and there are snails small enough for them to eat. The
only things they are interested in eating are sinking algae wafers. I've tried shrimp pellets, frozen shrimp and bloodworms, regular flake foods, freeze-dried shrimp and bloodworms, and daphnia, but all they do is shake the food around till it falls apart, or take a bite and spit it out, and then leave. The algae wafers they really chow down on however. I'm happy they're eating and acting normally, but I wasn't sure if they'd get the nutrition they needed from only the algae wafers. Thank you for your time and any help you can give me.
<You might want to try "smooshing" a few of the snails (with your fingers)... to help your loaches develop an awareness ("taste") for the snails. Bob Fenner>

Black ghost knife attacked by loaches  1/14/08 We purchased a black ghost knife 3days ago and from the very beginning the fish swam near the surface on it's side and it seldom ventured to other parts of the tank. The fish was approximately 4cm in length. In our tank we also have 2 clown loaches, 2 Pakistanian loaches, 1 Corydoras, 1 angelfish, 3 gouramis and a small eel. <One Corydoras isn't nice. Corydoras are SCHOOLING fish, which means they should be kept in groups. Please add some more of the same species (unless you want to accrue a lot of bad Karma from the catfish gods).> We started noticing that the black ghost knife was being attacked by the loaches. The clown loaches are approx 6cm and Pakistanian loaches 4cm. The tank is 4feet in length (980 Aqua One) The tank has 2 plants and water is changed regularly, 25% biweekly. There is a large rock with many holes to swim through and places to hide as well as a fake pot with hiding capability. The temp of the tank is approx 28degrees C. The tank was 34degrees C when the fish was first put in; our thermometer was not working but I realised the temp when I stuck my hand in. I slowly reduced the temperature using ice blocks. The pH of the tank is approx 7.2 The bottom feeders are fed the appropriate pellets once a day and we were feeding the others blood worms. The only other thing I have noticed in the tank is a yellow (algae?) growing on the sides of the tanks in round circles similar to what would be seen with bacterial growth. We put in anti-algae drops and cleaned the tank to deal with this. I have not yet observed any re-growth. <Don't use Anti-Algae medications; they cause major problems, not least of all their toxicity to other organisms as well as producing nitrate spikes as all the algae die. What you have sounds like Diatoms, a type of algae that grows most noticeably in aquaria that are not adequately illuminated. Easily beaten by installing strong lights and lots of fast-growing plants. Nothing else works, other than manual scraping.> 1. do you think the ghost knife was unhealthy from the beginning judging from it's behaviour? <It was probably fine. But Apteronotus albifrons is NOT an easy fish, and is extremely sensitive to poor water quality as well as medications/potions of various types.> 2. is it normal for loaches to attack black ghost knives? <Loaches are, with a few exceptions, NOT NICE FISH. They aren't community fish (exceptions are Kuhli loaches, Weather loaches, and to a certain degree Clown loaches; everything else is more or less aggressive and should be treated as such).> 3. We would love to get another black ghost knife but not if it is doomed to die before it's time, can you suggest any other reasons for the loss of our fish and tips to keep one safe in future? <Hmm... not impossible to keep, and under good conditions live many (10+) years in captivity. But you do need to cover all the bases... these aren't like Danios you can just add to a tank and hope for the best. They have very specific needs in terms of food, hiding places, substrate, etc. Do read here: http://www.wetwebmedia.com/FWSubWebIndex/bgksys.htm If you need more info, get back in touch!> Thank you for your time. Sincerely, Ali. <We're happy to help. Good luck, Neale.>

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>

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>

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 Nicaraguenese, 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>   

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)>

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 Ghostknife 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 Ghostknife at the links below.  Best Regards, Gage http://www.wetwebmedia.com/FWSubWebIndex/knifefishfaqs.htm http://www.mongabay.com/fish/knifefish.htm  >

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>

Black ghost Knifefish  hi, I need some advice concerning my ghost Knifefish, I've got a 5ftx3ftx2ft tank(400 litres) I have 1 rather large goby an Arowana 2 angels and 1 Geophagus brasiliensis a few kuhli loaches and a bristle nosed Plec, all of which seem to get on fine. last week I fell in love with a ghost Knifefish but since he's been in the tank I've hardly seen him, or seen him eat anything. the goby that I've got is very greedy and I'm worried if the Knifefish getting any food, what should I do???? any advice would be greatly appreciated, thanks Julie < Your knife fish is nocturnal and will only come out a night. If you put on a red light bulb at night you will see him out an about. To make sure he is eating I would turn out the lights and then feed the tank. They can be very picky and sometimes only eat live food. I would place some live black worms in the tank after I turn out he light at least once a week. If you ever got an elephant nose then I would recommend the same thing. -Chuck> 

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

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

BGK   1/27/06 Hi there, I have a 35-ish gallon tank, to be moved up to a larger one soon. I was planning on keeping some smaller knife fish in it for now, however all my LFS's only carry black ghosts. I am aware that these grow to ~20 inches, am I right? <Rarely more than about eight inches overall in captivity> Are there any other more suitable knifes for my tank? <... would have to know more re> It is well planted, with driftwood, etc., (lots of hidey-holes) and I have several medium sized (~3 inches) Gouramis, along with some small, 2 inch clown loaches, a whiptail cat, Pleco, and CAE, <This last may become trouble in time> as well as some cichlids. <... sounds pretty crowded... S.A. Knifefishes are not ready "fighters" for food, space> I am planning also on introducing some Cory cats, African butterfly fish, a dojo (weather) loach, and possibly (but not likely) an elephant nose. <Then skip on the knife/knives> I realize the elephant nose should be alone in a tank of my size, but could I keep more than one BGK (small, ~3-5 inches)? How fast do these guys grow? Will there be any conflict between them, or will the elephant nose and BGK's electric field thingies bother each other? <Yes> As well, what about their feeding habits? Will their nocturnal behaviour keep one or the other from getting food? I also have some medium sized angels, but I don't think they'll be too much of a problem...if you guys have any better suggestions to my choice of fish, please tell me. My LFS's all tell me that everything will work out fine, but then again, they would tell me Neons are compatible with knife fish if it meant I would buy them. I do kind of have myself set on knife fish, because of their method of movement, but please tell me if you do not think I have adequate housing for these fish. I realize I am asking quite a bit right now, so I thank you in advance for anything you can do for me -Eddy <You need more tanks Eddy... Bob Fenner>
Re: BGK   1/30/06 Thank you for the quick response. I will be keeping my CAE in a different tank, it is getting pretty aggressive... I think I'll skip on the knives till I get at least a 50 or 60 gallon, will this do for the knives? I'll stick with the Corys and butterfly fish for now. Thanks, Eddy <Welcome my young friend... Have you considered working part time at a local fish store... or volunteering (if one's nearby) at a public aquarium? Bob Fenner>

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