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

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

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


Would you settle an argument and maybe save a Black Ghost Knifefish's Life; filtr.      3/25/17
I have a friend who has a 72 bow front. It is completely empty and he wants to get a BGK to be the solitary fish in the tank. His set up is perfect (according to what I've read on these fish, I've never owned one) except for one thing - filtration. I've repeatedly shown him the WWM postings that state that these fish need a high water flow - as much as 8 - 10 times tank capacity every hour, but he insists that is only for adults; that a juvenile will do fine in the 72 with his Cascade 1000 (I think the gph for that model is around 267 gallons per hour) until it has matured. He believes that a higher gph rate would leave a juvenile plastered up against the side of the tank. He has agreed to abide by your response to this post.
<The Cascade won't do... the ratings for power filters are generally way off in terms of what they really deliver. He'd need three-four of these hang-ons to move enough water, provide biological filtration. Perhaps adding a large canister filter in addition. Bob Fenner>
*Renee *

Re: Black ghost knife - quarantine and tank mates. Water quality/sys.   11/18/16
Hello again,
I finally got the GH and kH test kit, my readings are:
tap water GH - 11 drops, hence 11 degree about 200 ppm
tap water kH - 6 drops, hence 6 degrees about 100 ppm
the drinking water dGH is about 3 degrees 50 ppm
The tank dGH is about 8 degrees, so I'm guessing it should be fine and I don't have to mess with water chemistry. Now ill just have to wait and get the fish :) I cannot thank you enough for responding to all the e-mails even if they're silly. Thank you ! You've been a life saver.
<Thanks for the kind words, and I agree, your water chemistry sounds fine for Black Ghost Knifefish. As we've discussed before, water quality and oxygenation are more important. Good luck, Neale.>
Re: Black ghost knife - quarantine and tank mates. Now feeding, avoiding B vitamin deficiency   11/18/16

I was just going through your article on Thiaminase and vitamin B1 deficiency in fish. As this is important, I was looking into foods that are rich in this to form a varied diet for the BGK. and I wasn't sure if some of these foods can be fed to these fish Hikari pellets, earthworms, cucumber, beef heart, shrimp, green peas and tilapia fish fillet in general
<These are all good. Beef heart should be used sparingly, as it is quite rich, but is a classic "safe" food for aquarium fish because it isn't fatty.>
foods that I came across is rich in Thiamine are - mackerel,
<Sparingly. Good in terms of health. But oily, so makes a BIG mess. I've used mackerel on the day I do a water change, so I can change the water after the fish have eaten it up. Make sense?>
lean pork (can pork be fed for fish? I'm a vegetarian so I'm not sure about how meat works except that I need to take off all the fat from it first) ,
<No, don't feed pork to fish.>
liver (chicken or pork),
<Unlikely to be eaten, but tiny bits might be eaten by some herbivorous fish. I doubt Black Ghosts will eat it though.>
wheat bread
<Very occasionally to herbivorous fish does no harm. But nutritionally not particularly useful because most fish don't naturally consume starch.>
and yeast.
If this doesn't work out, can I use vitamin b1 supplements meant for humans?
<Theoretically, but getting the dose right will be difficult. Normally freshwater fish don't need vitamin supplements. Just offer a nice varied diet.>
same for erythromycin cause its difficult to get hands on API here in India.
<Understood. But again, dosing is difficult, so unless a vet can help you, best avoided.>
Also, will fluctuations in dGH have the same affect as ph ? cause' my tank dGH had lowered to 8 from 11 in 3-4 days.
<General hardness shouldn't normally vary much, if at all. If it does, then the best approach is to do small, frequent water changes to "reset" it. Say, 10-15% every couple of days.>
Thank you in advance. Sorry about asking too many questions !
<Most 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>

Black Ghost knife; env. poisoning: Too much new water       12/27/15
Hello, I have a ghost knife approx. 30cm living in a clear Perspex tube in my communal tank. Recently I changed 80% of the water ,
<Yikes; do see/read my piece on WWM re "frequent partial water changes". In these years, I would only change out about a quarter of the water... for reasons stated>
cleaned the filters and re stabilised the conditions. Whilst I was doing this I removed the ghost knife into a container on his own. All ok . Three hours later I put him back in the tank and now he seems to be having trouble remaining the right way up. He is upside most of the time. He still eats and can get upright for this but then moves into the upside down position. I have fed him shelled green peas which he likes but he still is swimming upside down in his tube for five days now. Any suggestions would be greatly appreciated. Thank you . Sincerely Helen and “Phantom”
<Am out of the country; but will look for you: http://www.wetwebmedia.com/fwsubwebindex/fwh2ochgs.htm
and the linked files above. I WOULD try overdosing (two, three times the amount) w/ Amquel or equivalent product. Going forward, store and pre-treat the 20-25% of water to be changed out ahead of time (like a week).
Bob Fenner>

Tank            10/11/15
Hello. Would a black ghost knife fish do well In a 45 or 70 gallon tank.
<Mmm; yes>
I want the coolest fish I can but I don't know which size I'm getting yet.
I also like discus, Amazon puffers, dwarf gourami, and yoyo loach. What would u recommend on this. Also what kind of filter, heating, decor, substrate, and other tools do u recommend. I only have a 5 gallon now and really need to upgrade. Thank you
<.... Please learn to/use WWM. READ here:
and the linked files above. Bob Fenner>

Re: Black ghost knife sick (Bob, any other ideas?) Sys.      3/12/13
Hi Bob,
What is your opinion on using sand for substrate for my black ghost knife?
<Is fine as long as not too fine (grade-wise)... creating maintenance/mulm-detritus accumulation issues. Oh, and do check/see that it's not too alkaline... lest the pH be driven too high for Apteronotids. BobF>

Apteronotus River Tank?    3/15/12
Hello, I have two tanks that have been set up for about a year, currently a
10 gallon that I started with and a 30 gallon that now house's two fancy Guppy's (1 1/2 each) an Algae eater (2 Inch
<Is this... Gyrinocheilus? If so, see WWM re, and get rid of it>
) and one long fin zebra Danio
(2 Inches) and very recently a Black Ghost Knife fish (4 inches) he has started eating out of my hand and I must say it is by far the most amazing thing I've seen any of my fish do! All of the readings are perfect in the tank and the water is crystal clear with a very high water turn over rate so he should be fine till his new home is set up, (nitrate 0, Ammonia 0, and PH-7, plus weakly water changes).  I know this tank is far to<o> small for him and I am currently in the process of setting up a new tank, (55 gallons (still to small for the long run but eventually I plan on getting 75 gallon + tank in a few years) that I intend to make a river tank that will have a one directional flow ( two powerheads with two returns on the opposite side of the tank to keep the water flowing in one direction.)
    My question is this, would my BGK thrive in this environment?
<Mmm, the current? Yes>
 I know they come from rivers, and waterfall pools in the Amazon and like a high turn over rate in a tank, but would they be happy in my purposed simulated environment?
<Likely so>
    My next question is one of tank mates,  I would like to get a verity
of loaches for this river tank, including clown (possibly 2?) Botia almorhae, (2-3?) and preferably some Beaufortia kweichowensis (butterfly Hillstream loaches) are these compatibly tank mates? and most importantly would my BGK eat them?
<It will not; though may be bothered/pestered by their swimming about>
    My final question would be what to make the substrate in the tank if this is a possible set up? I know Loaches like to dig and have very sensitive barbels but would it be alright to lay smooth river pebbles for the base of the tank?
<Finer natural gravel would be better. Please read here:
( I need something to cover up the piping for the river systems powerheads and returns so I do not think sand will work but again I may be wrong.) I plan on putting drift wood and various caves for the loaches and BGK to hind <hide> in, out of the current and was wondering what type of plants would be good for the surface since most of the spices here are nocturnal?
<My fave: Ceratopteris>
 I'm fond of the idea of lily pads yes? no?
<Possibly... but not Nymphaea...>
   Any help you can offer would be GREATLY appreciated as I really want this tank set up to work but if it can't then I'd rather know that before sacrificing these amazing species for my amusement.  Thanks again!
<Welcome. Bob Fenner>

BGK and blasting sand      3/5/12
Excellent and very informative operation you folks have here, thank you for taking your time to do this.
I have one quick question...
Do you think that the magnetic nature of some blasting sands (for example: Black Beauty sold at Tractor Supply) could wreck havoc upon the "electronics" of a BGK?
- Chris
<Yes; I do think ferrous materials, any sort of strong/detectable magnetism in their system can prove problematic for weakly electrogenic fishes. Bob Fenner, who's 1973 survey piece on this group is archived on WWM>

Is this too small for a BGK?    3/4/12
I have been running a 2ftx1ftx1ft tank (62 Litres) for about a month. I have been adding fish to it and now have 2 sucking catfish (4cm ea), 1corydoras (2cm),
<These are social species>
1 molly (4cm), 6 neon tetras,
<These two are not compatible... see re their water conditions on WWM, books>
and the newest addition, a black ghost knife (approx. 7cm).
<not compatible or a suitable size system for>
 I have seen mixed responses online for the size of an appropriate tank for a BGK, and would like to know if this is
too small. The tank does not seem crowded and the BGK looks comfortable in its hiding spots and coming out at night. I know that they can grow quite large but will this sized tank have much of an effect for the health of the BGK for now? The filter I have turns over 480L/hr and the tank is regularly cleaned also.
Regards, Mitchell.
<Read; what you have here won't work. Bob Fenner>

Best option for Black Ghost Knife Fish, sys.    1/19/12
<Hi there>
I want to start out by saying that I probably look at your website a couple times a week.  I have had freshwater fish tanks for my whole life since my dad got me into it as a kid and I just love reading about all kinds of freshwater fish.  So thank you for your very helpful and informative site. 
I am looking to get your thoughts on what would be the best option for a Black Ghost Knife fish.  I have two tanks that I have been considering putting one in but I have gotten conflicting information from numerous sites.
I have a 75 gallon that has been set up for about 18 months with Angels, Discus and Geophagus altifrons (they all get along very well).  Water temp is 81 F, Nitrites 0, ammonia 0, nitrates 10, PH 7.  I have a Fluval fx5 for filtration. 
I also have a 55 gallon that I built a River Tank Manifold (http://www.loaches.com/articles/river-tank-manifold-design) cold water tank.  Water temp is currently 70 F, nitrites 0, ammonia 0, nitrates 5, ph 7.  The sponge filters/powerhead system is currently the only filtration but I am going to be putting in a HOB filter soon.  I have 8 Golden Barbs, 12 white cloud mountain minnows and 4 Hill Stream Loaches.  This one has only been running for about a year since my wife wouldn't let me build it until I agreed to keep it in the garage.  Its freezing here right now so I have a Fluval 200 and a 300 heater in there to keep it at a stable temp.
I have read that they come from fast moving streams near waterfalls which makes me think it would be great for the 55 gallon but the temperature might be too low.
<It is>
 I can raise the temp if necessary but really just want to know what would be the best temp for them.
<Better to place the Knife in the 75 if there's room, and leave the 55 w/ the present inhabitants in the water conditions as they are>
  I have read the max temp for them is 75 but then on other sites have read a range of 73-82.  I know the WCM Minnows would probably get eaten but I have a friend who would take them if I wanted to move the BGK into that tank. 
On the other hand I read somewhere that someone kept their BGK with their angels and that intrigued me so I thought that might be an option in my 75 gal.
<Perhaps... though it may be hard to get food to the animal there, due to competition>
Anyway any advice would be much appreciated.  I am kind of leaning toward raising the temp in the 55 gallon to about 73, getting rid of the white cloud mountain minnows and putting the BGK in that one but want to do what is best...if either is a good option.  I also do not want to risk harm to the hill stream loaches or the barbs.  If not, I don't have to put one in either.  ...that just gives me an excuse to get another tank!
<The best option here>
Thank you for your time.
<Welcome. Bob Fenner>

BGK sys.   5/1/11
Hey guys!
Is a 125-150g big enough for my BGK when he is full grown?
<Should be, but do be aware most casual aquarists kill their Black Ghosts long before they reach full size (which can take a long time, ten years perhaps). The usual issues are lack of food, insufficient oxygen,
excessively warm water, and above all, poor water quality, including non-zero nitrate levels. At one point scientists were experimenting with using these electrical fish to monitor water quality -- when water quality
drops, they become stressed and their electrical field alters in such a way it can be detected with appropriate sensors. These fish are incredibly intolerant of the usual conditions offered in community tanks. Cheers, Neale.>

BGK sys.     4/26/11
How long can my fish go without filtration and heat? The power was knocked out around 5am and will be back on around 5pm at the earliest!!
<Read here: http://wetwebmedia.com/ca/volume_5/volume_5_3/power.htm
Re: BGK sys.
Thanks, Bob!! Your info is, as always, both helpful and refreshing!
<Do insulate that tank! And welcome! BobF>
Re: BGK sys.
Okay I will do that. The ambient temperature of the room fluctuates between 80-75f during the day. Should I still insulate or wait until tonight when the temp. drops to about 70f in the room?
Re: BGK sys.     4/26/11

Additional question... BGK sys.  12/28/10
hi Neale,
Also if I do the 75 or 70 wide could I now entertain the idea of a Black Ghost Knife?
<Apteronotus albifrons has very specific needs in terms of water temperature, water current, and oxygen levels, as well as being difficult to feed. While 75 gallons would be adequate, please do review the needs of the BGK prior to purchase to ensure that the conditions you have in your tank -- and are required by your existing fish -- match those of the Knifefish. The vast majority of BGKs die within a year of purchase and hardly any reach full size -- and there's a reason why this is the case. For generic community tanks, the African Knifefish Xenomystus nigri is generally far easier to keep. Cheers, 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 Knifefish 9/7/09
<Hello there>
My fiancé and I have recently decided to get (back?) into the fish keeping hobby.
<Like jarheads and bicycle riding; methinks no one ever really leaves altogether>
Both of our parents have had fish for many years. We have absolutely fallen in love with Black Ghost Knifefish. We would love to get one. We will be getting a large (around 90 gallons) aquarium within a month or two.
This leads me to my question. I have read in several places including this site, that these fish prefer soft water with a low pH.
<This is so>
Our tap water is EXTREMELY hard, and has a very high pH. The pH is somewhere between 8.4 and 8.8.
The hardness of the water tests at least as high as the test strip goes (300 ppm). (I cleaned our shower head shortly after we moved in, 5 months ago. It is already about half plugged up!) The KH also tests at least 300
ppm. Buying reverse osmosis water from a fish store is not really an option, as the closest store is 2.5 hours away.
<Wouldn't do this in any case... Get your own unit and use it for your petfish and potable (drinking, cooking) needs>
I have read that it is better to allow a fish to adapt to the local water than try to alter it, causing the levels to fluctuate.
<Not in such extreme cases as yours, no>
But then, I also read that BGK are very sensitive to water conditions and are not easy fish. I guess my question is, which would be the lesser of the two evils in this case; trying to 'fix' the water parameters and
risking fluctuations, or try to have the fish adapt to water vastly different from what is natural for it?
<I would at least partly fix... i.e. mix RO with some tap>
If it would be better to try to soften the water and lower the pH, how would one go about doing that so that there is less chance of large fluctuations?
<Please read here: http://wetwebmedia.com/FWSubWebIndex/fwsoftness.htm
and the linked files at top>
If you have any other general advice about these fish that you feel would be of help to us, we would greatly appreciate it. Thank-you so much for your time.
<What little I know re the husbandry of Apteronotids is archived on WWM.
Bob Fenner>
Black Ghost Knifefish      Neale's go      9/7/09

My fiancé and I have recently decided to get (back?) into the fish keeping hobby. Both of our parents have had fish for many years. We have absolutely fallen in love with Black Ghost Knifefish. We would love to get
one. We will be getting a large (around 90 gallons) aquarium within a month or two. This leads me to my question. I have read in several places including this site, that these fish prefer soft water with a low pH. Our
tap water is EXTREMELY hard, and has a very high pH. The pH is somewhere between 8.4 and 8.8. The hardness of the water tests at least as high as the test strip goes (300 ppm). (I cleaned our shower head shortly after we moved in, 5 months ago. It is already about half plugged up!) The KH also tests at least 300 ppm. Buying reverse osmosis water from a fish store is not really an option, as the closest store is 2.5 hours away. I have read that it is better to allow a fish to adapt to the local water than try to alter it, causing the levels to fluctuate. But then, I also read that BGK are very sensitive to water conditions and are not easy fish. I guess my question is, which would be the lesser of the two evils in this case; trying to 'fix' the water parameters and risking fluctuations, or try to have the fish adapt to water vastly different from what is natural for it?
<In this case, going for a 50/50 mix of tap water and deionised (or RO water, or rainwater) would make sense. That said, Apteronotus albifrons isn't usually killed by water chemistry issues, but by water quality
problems. It inhabits fairly cool (around 25 C/77 F) bodies of water around rapids and waterfalls, and is used to very high oxygen levels. In the average tank with a poky hang-on-the-back filter it simply doesn't enjoy the kind of water circulation -- especially at the bottom of the tank -- that it needs. So, you need a big filter, rated at 8-10 times the volume of the tank in turnover per hour. So a 90 gallon tank would need a filter up to 900 gallons per hour. Some of that circulation might be done using powerheads in addition to one large canister filter, but water quality is critical. Zero ammonia and nitrite, obviously, but also low nitrate, sub-20 mg/l levels are important.>
If it would be better to try to soften the water and lower the pH, how would one go about doing that so that there is less chance of large fluctuations?
<Yes, if you can't keep water chemistry stable, then don't undertake such.
Hence, better to have moderately hard, basic water (10-15 degrees dH, pH 7.5) that keeps steady than trying to aim for soft, acidic water with a pH you can't control from week to week. That's why I suggest a 50/50 mix of hard and mineral-free water, rather than anything more extreme.>
If you have any other general advice about these fish that you feel would be of help to us, we would greatly appreciate it. Thank-you so much for your time.
<Is some stuff written here. I happened to have a piece about these and other knives in June's issue of TFH Magazine, so if you happen to have that, or your library has a subscription, then check it out. Cheers, Neale.>

Listless Black Ghost Knife  5/10/09
Hi Guys
I have read through your site (which is fantastic btw) and have been unable to find anything similar to what I am experiencing.
I have had 2 black ghost knife fish in a 500 litre tank (with a variety of other fish, catfish, loaches etc) for about 6 weeks. They are both around 10cm's and very friendly and social. The other day I noticed one (Fred) laying totally flat (no movement at all) on the gravel inside one of the ornaments. I freaked and lifted the ornament thinking he was dead only to have him swim away and continue behaving normally. Today he was listless with his tail dragging on the bottom of the tank and can barely swim at all.
<Do be careful keeping multiple Apteronotus albifrons; like all electric fish, they tend to "jam" one another when in close proximity. The dominant specimen actually "bullies" the weaker specimens, forcing them to use less
favourable frequencies. In extreme situations -- as when you have just two specimens in a relatively small volume of water -- the dominant specimen may batter the other specimen to such a degree that it doesn't feed or act
normally. Now, while I'd expect 500 l (130 US gal.) to be adequate for two specimens, you never really know for sure. Apteronotus albifrons is one of those fish best kept either singly or in groups of six or more specimens,
so that bullying isn't likely going to be a problem.>
I quarantined him straight away and currently have him in a guppy breeding cage to keep him off the bottom of the tank - he is not moving at all and I don't know what to do - especially since it is now 8.30 on a Sunday night
so no pet shops open!
<First thing you do is check the water quality and water chemistry.>
I do about an 80ltr water change every 2-3 weeks and I've checked the water with a master kit and all of the levels are within good range with no ammonia or nitrate/nitrite issues.
<Good; also consider oxygenation and possible introduction of copper (e.g., with medications) or other toxins (e.g., paint fumes) that might stress these highly sensitive fish.>
They are fed tropical flakes, frozen bloodworms, dried shrimp and a frozen tropical meat mix - alternated over the week and small amounts a couple of times a day. Ginger, the other ghostie seems fine, as do the other fish but
I am very concerned as he has no obvious injuries, no white spots or coatings and is obviously very sick.
<My gut feeling is this is was initially a social, rather than environmental, problem, and if you moved to its own tank, the other specimen would pep up, given good conditions and a healthy diet. But do consider the other factors mentioned as well.>
Please please help!
<Good luck, Neale.>
Re: Listless Black Ghost Knife  5/10/09

Hi Neale
Thank you for responding so quickly.
<No problem.>
Unfortunately he died very shortly after I emailed you. One strange thing, it appears as those his eyes have disappeared.
<Likely bitten out post-mortem; for whatever reason, these tasty morsels seem to go first! Eyes are also among the first things damaged when fish fight, so again, think carefully about social behaviour issues whenever you
see this symptom.>
There's no wounds around them or anywhere else that I can see. So I don't know if that's a result of bullying or what they normally look like once dead?
I will keep a very close eye on the rest of tank over the next couple of days.
<Wise; would suggest you keep one electric fish per aquarium in future, unless you have a specifically gregarious species, such as Eigenmannia, and purchase a school of them (6+) together.>
Thank you very much for your help.
<Cheers, Neale.>

Black ghost... hlth, sys., gen.   -07/18/08 Hello. <Hello,> I found your cool site accidentally and have learned a lot from reading on it mainly about Black Ghosts (great job keep it up). I have gotten into the hobby on an unfortunate account that my dad had gotten cancer and I was taking care of his fish 2 tanks until he passed away. <Sorry to hear that.> Because of getting back to a regular work schedule I was not able to get there regularly anymore to help my step mom take care of the tank, so she asked if I wanted it. I took it to my place using same water transported in buckets did partial water change and so on when I got it to my place. I guess the move was too much for them and the fish got ich and died off after several weeks. ANYWAY, after letting the take "I hope" get healthy so to speak.. as per advice of my LFS put some food in it with no fish said it would keep cycle somewhat going. <You can indeed cycle a tank by adding a pinch of flake, though you need to also do water changes, and also keep adding portions of food every 2-3 days. As the food rots, it produces ammonia, and that kick-starts the cycle. It will still take the usual 4-6 weeks to fully cycle, and you need to be measuring the nitrite level to see when the cycle is finished. If you just add one pinch of food and leave it at that, then all that happens is that one portion of food decays, the ammonia goes up, goes down, and then nothing much happens. You MUST keep adding food so that the bacteria have a constant source of ammonia. Essentially you're keeping fish, without the fish!> I turned up the heat to in 90's for couple weeks to hopefully kill off any ich that might of still been in there. Finally getting to the BGK they are such a great fish. <Yes they are, but also extremely difficult to maintain. Being very sensitive to water quality, under no circumstances would you put one in a tank less than 3 months old. You want the filter to not only cycle, but also "settle down". The problem is that a new aquarium goes through a period where the filter sometimes misbehaves, and you get small nitrite or ammonia spikes. Exposing Apteronotus albifrons to this phase would be a disaster. There's also a period where the fishkeeper needs to get the hang of cleaning the filter without harming the bacteria, and also doing things like siphoning out detritus from the substrate, learning how much food to use, and performing water changes.> He seems to go against a lot of things I was reading about them. and I guess its on a fish to fish basis.. he is almost always out even with the light on (as matter of fact I am watching him swim around tank now and the light is on, he started eating out of my hand after at first time trying one week after I got him, he eats flakes when I put them in tank for my Kribensis. and he eats frozen bloodworms that I put in tank at lights out. <All quite normal for well-adjusted, happy animal.> This brings me to a question. I noticed today that the bottom fin has a couple splits in it What are the usual causes of this? <Not "usual" but may be either rough handling (netting, transport); biting (by other fish); scratching (check for sharp ornaments or gravel); or early stages of Finrot (check ammonia/nitrite ASAP). You mention Kribensis, and all Pelvicachromis spp. are territorial and quite prone to biting even substantially larger fish. I have a small female Pelvicachromis taeniatus that quite happily charges and chases pufferfish. So while basically good community fish, their feistiness is out of all proportion to their size, as is often the case with that family we call the Cichlidae.> There doesn't seem to be any discoloration he seems to be aggressive towards my Kribensis that I just put in about 4 days ago though that has become less frequent. Kribensis doesn't seem to like to be around him and swims away when BGK swims near him, so I don't know if Kribensis got brave and did something when lights were out, but as I watch him he still constantly swims away from BGK. <They are competing for the same resources, namely caves, and will view each other as potential rivals. It is absolutely normal for Pelvicachromis to be utterly peaceful towards midwater fish but total terrors with regard to bottom living species. Does obviously depend on the size of the tank; Apteronotus albifrons will need a big aquarium, something upwards of 220 litres/60 gallons. Anything less and you WILL be asking for trouble. They are fish of fast-flowing rivers, so also need a very strong water current to burn off all their energy. I'd be looking at canister filters providing not less than 6 times the volume of the tank in turnover per hour. Forget about using anything hang-on-the-back or air-powered!> So was wondering if you had any thoughts on what might cause the splitting of the fin and what I should do so it doesn't get worse. Thank you MUCH... and again thanks for this great site. <Hope this helps, Neale.>

Ghost knife, BGK beh., sys.    3/3/08 I have had a 40 gallon freshwater aquarium for several years, and until recently the tank was home to a few Oscars who eventually out grew the tank and now reside in a friend's outdoor Koi pond. This past Christmas 12/07 we decided to re-establish the tank with two silver dollars and one incredibly elusive ghost knife. The tank contains your basic under gravel filter, bio wheel, plenty of colorful plastic plants and a long plastic tube, guess who lives in the tube. When I purchased the ghost knife from the pet store he was in a tank with several other ghost knifes and no real shelter, he was swimming around the tank, front wards, backwards and performing all sorts of tricks. Now that the ghost knife has a place to hide he never comes out of his tube. I love to tell friends about this mysterious looking fish, however when they ask to see him I can only reply with Ummm sorry he's still hiding. Any suggestions on how my ghost knife can overcome his shyness? <Apteronotus is only active in dark, shady aquaria. You need a soft substrate for digging, lots of rocks, and real or plastic plants that reach up to the surface of the aquarium and produce lots of shade. Use LOTS of floating plants (Indian Fern is ideal). What you do not want is brightly coloured gravel, bizarrely coloured plants, or bright light. Sounds and vibrations must be minimised, so don't put the tank near slamming doors or loud TV sets. Bob F just wrote a piece on setting up an African-themed aquarium, and the photo of the tank shown there is precisely what you need for Apteronotus, so have a read: http://www.wetwebmedia.com/FWSubWebIndex/fwlvstksel.htm Apteronotus live in major river systems and expect excellent water quality and lots of water movement. I'd be aiming for NOT LESS than 6 times the volume of the tank in turnover per hour. These are NOT easy fish to keep, and when kept poorly become shy, and often die.> I also wanted to know if adding aquarium salt when doing water changes was harmful to the ghost knife? <Yes.> I know with other fish that I have had, I have added approximately 1 teaspoon of aquarium salt for every 10 gallons, however I recently read that ghost knifes are not particularly found of chemicals such as prime coat and aquarium salt. <Indeed. The addition of Prime Coat and aquarium salt is unnecessary in a properly run aquarium. Instead focus on filtration and water quality. 50% weekly water changes and nitrates below 20 mg/l, and of course zero ammonia and nitrite, are what you are aiming for. Cheers, Neale.>

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.>

BGK... sys.     01/13/2008 hi there, I have a quick question. What is the minimum tank size for a black ghost knife fish? Also are they freshwater or brackish? Thanks. <... a small individual Apteronotus... 29 gallons... a full-size one... at least 55... Strictly FW... RMF>

Re: parrot fish with Mormyrus  tapirus (freshwater African dolphin)... Now BGK sys.  1/9/08 p.s. after doing some more research, I fear that my 55 gallon will eventually be too small for the black ghost fish. is this true? <Eventually, yes. Maximum size in the wild is 75 cm, though aquarium specimens are generally smaller, around the 50 cm mark. While this takes many years to reach, this is ultimately a better fish for the 75-100 gallon tank than the 55 gallon tank. So does depend on where you see yourself five years from now in terms of aquaria.> if so, he's going back to the store as well.... <Hmm... does underline the need to research the fish *first*, then spend the money. Cheers, Neale.>

Was: BGK/Cycling a Tank/Dyed Fish 8/2/07 Thank you so much for such a speedy response, it means so much. To answer your questions; The tank I have him in is only a 10 (I know he will grow out of this very quickly but he'll only be in it a couple more days.) I figured this was okay as when I got him he was no more than an inch big. He shares the tank with two "painted" tetras that got put in there a day after I set the tank up. They did fine, so I a day later I put the BGK in. Unfortunately, I was told 24 hours was all it took to cycle a tank [And I work at a fish store ;\ ] After setting up the tank and reading some information on your website, I realize I should've let it run for at least 2 weeks. <Please read much more on cycling tanks. You could let a tank run empty for a year & it wouldn't cycle. Find out more about the bacteria needed to break down ammonia to nitrites, then to nitrates, which much be removed by weekly water changes. This entire process can take 2 weeks, if "fishless cycling" & up to 6 weeks if cycling with fish (bad idea--stressful to the fish). All this info is on our site. For an instant cycle you can use Bio-Spira. I recommend you use this to cycle your larger tank immediately. You owe this to your customers to know all this. Please urge your manager/owner not to carry dyed fish! See: http://www.deathbydyeing.org/ (can't seem to get that site to work but excellent info there), http://en.wikipedia.org/wiki/Painted_fish http://www.practicalfishkeeping.co.uk/pfk/pages/campaign.php Just do a search on "dyed fish" & you'll find countless arguments against it. I will not buy from any store that carries them.> But I have kept that in mind as the BGK's new home, a 29 gallon [and not permanent] home is being cycled as we speak. <Check into the adult size of your fish. You will eventually need a minimum of a 90g tank. You owe it to your customers (& the fish) to know the adult sizes of all the fish you sell & the minimum tank size for an adult. You are aware this fish won't eat flake food? My 15" fellow only eats live blackworms.> Anyway, as soon as I got your e-mail I ran out and got both the Melafix and aquarium salt. So I'm hoping by tomorrow, he will clear up a bit. Again, thank you for your helpful response, and your time, I appreciate it very much. <I suggest daily 50-80% water changes, until you can upgrade him to a cycled tank. ~PP> -Adam

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

Black Ghost Knife I read that a BGK likes tank temp.s up to 82 degrees. I've raised the temp. to help cure him of a series of illnesses and he's been in an 84-85 degree tank for about a month and a half now. How long can he tolerate the higher temperatures? <Indefinitely actually... will shorten lifespan a bit... but the only real worry here is aeration... dissolved oxygen is less soluble and metabolic rates elevated at higher temperatures...> I'm still treating him (with Paradigm for flukes, worms etc) so I wasn't planning on dropping the temp until this one hopefully goes away. Thanks so much for all your great info - you've been a really wonderful resource. <Glad to help. Bob Fenner>

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

Ghost knife fish Hi,     I'm totally new to keeping fish ..... Recently, (about 2 days ago) I bought 2 knife ghost fish and a new fish tank for them .... I did not do research before buying them. So here's the problem ... the new tank is totally empty .. I haven't had time to go get those "hiding" places for them .... Only place they hide is behind a pump in the tank and they seems to be fighting for the space ..... Do I have to separate them using a partition in the tank ? Also one of the them had the fin like "broken" that like hair .. not in one whole piece as like the other... is there any wrong with it ? and what should I do ?, < Black ghost knife fish are nocturnal (feed at night), so they don't thrive in brightly lighted aquariums without suitable places for them to hide during the day. You really don't have to separate them as long as you give each of them their own shelter to go to  during the times you have the lights on. Get a couple pieces of PVC pipe from the local hardware store and throw it in there for now and they will be fine . Although the tank will not look to good with a couple pieces of white pipe in it.-Chuck> Thanks a lot Chasel

Re: Attempt to save Ghost knife fish Hi,     Thanks for the last reply. However, I'm sending this out in attempt to save my fish. I now have a tank with some plant and a log inside, 2 black ghost knife fish and a swordtail. They live fine with each other and I had been feeding them with flask and they ate them. < Sorry . don't know what flask is so I don't know the significance is if the black ghost knives ate them> But just yesterday, I notice my 2 black ghost fish are not doing well. They aren't moving much even when I turn the light off ....and not feeding either. I have no idea why this is happening. I don't have any tester to test the water condition. My last water change of 30% was 5 days also. They were still fine then. I don't know what else I can do. All I did was a 30% water change this morning hope to save them. Any similar situation to help ? < Well I guess we need to determine if their behaviour change is a symptom of something more serious. Try feeding some California blackworms, often called Tubifex still at some pet shops across the U.S. If they don't go for this look carefully for signs and symptoms of some things we can specifically treat. I really don't like to medicate a tank if it is not needed. In the meantime make sure that the water is up about 80 degrees F and the filters have been serviced and do another 30% water change. This should take care of any water quality problems. If the fish don't respond then I would remove them to a hospital tank were they can be observed more closely and look for symptoms.-Chuck> Thanks Chasel

Re: Attempt to save Ghost knife fish, II Hi,      Its was a typo on the food I feed them. I meant flake. But anyway, one of them is dead and the other one is laying on the floor now. I did another 30% water change, no use. I move the last one to another tank with and 80% fresh water no use either. Thanks anyway < Black ghosts like warm acidic water and usually don't eat flake food. If the water they were kept in was hard and alkaline then their kidneys may have failed due to an imbalance of  minerals in their system. Hard to tell. Sorry about your fish.-Chuck>

Lifespan of a Ghost What is the life span for a typical Black Ghost? How sensitive are they to moving to a new tank? Nicole <Couldn't find anything on lifespan so I'm not really sure. They do like soft acidic water conditions. Move them the same as any other. Float him in the new tank in a bag of his current water. give it 20 minutes or so, then slowly pour in some water from the new tank. Do this a few times over an hour or so and he should be fine. If you test water check the pH of both new and old. If they are the same, you just need to match temp. Don>

Another Black Ghost Knife Question I Have a Black Ghost Knife 4", If I put on my Aquarium light (which I haven't turned on  since I had him, 4 months) will it stress him out or kill him well because they hate light and are nocturnal)? He does have this ornament with holes in it that he goes in and out of (prefers that then the ghost tube), can he be in there if the light is on? < Black ghost knife fish are nocturnal and should have a hiding place to retreat to when the aquarium light is on. They should be fed just after the lights are turned off.-Chuck> Thank You Jahner

Ghost knife? Hi there guys,<Hi Guru, MacL here with you.> Absolutely love your web site.. I was wondering if you knew what size tank I would need to get my ghost knife to grow to its full length, and also roughly how big it would get in a 900L tank (approx 240 U.S. gallons and  200 UK gallons). <Guru I need a little bit of clarification. Do you mean a black ghost or one of the other types of knife or bony fishes? If you take a look here you might find your answer, otherwise if you can clarify for me a bit we can go from there. http://www.wetwebmedia.com/FWSubWebIndex/knifefishes.htm> Regards Guru

Black Ghost Knifes Hello. I read the FAQ but I am unable to find the answer for my question. I have a rectangular tank is 16" x 9" x 11". But I have 2 ghost fishes. It is healthy for the fishes? I noticed that they sort of dance/swerve/bite each other in that sequence. I am afraid that they are trying to kill the other off. I bought a volcano rock (that's what the shop says) for the fishes to hide. Seemed like they don't share. Should I buy another one to keep the other happy? 1 last thing, the fishes don't eat the flakes floating on the water. Instead they scoop around the top edges of the tank. Thanks. I really those answer. Please <These fish need a larger tank, at least 55 gallons even that may not be big enough to house 2 of them, they are aggressive towards their own kind.  Check out the link below for more information on these fish.  Best Regards, Gage http://www.mongabay.com/fish/knifefish.htm  >

Black Ghost Knife Hi Bob, Nice site. Looks like you've got articles on everything in here. Hence I thought I might ask some advice. I've been keeping fish for a few years now and last year I took on a Black Ghost Knife fish as a favor for my local pet shop. I am aware of how long this fish will live and how large it will grow and I plan on getting a 60g tank in December. At the moment I keep her in a 20g tank with a few tetras and a Betta but I have a spare (34g) tank that I've been using as a hospital tank for my marines. (I've added a pic of the big fella) Specifics are pH 6.8, Temp 25.4 'C. What I'd really like to do is swap the two round and have a good size tank to keep the BGK in. Thing is I can't really find out that much about them. I know it seems healthy, good color, eats well (even a couple of tetras once) and its very active at night. The fish has grown 1" in the last year (now 4") and now that I've given the rest of the community to my little sister (fast becoming an avid fishkeeper) I want to set up a species tank. Ideally I want at least one other BGK but sexing is impossible and I've read that they can be violent towards one another. Aside from these fish living in South America I know little else about their habitat. I was thinking of having a ground basalt strata with lots of spiral Val's and some floating plants to give better cover. Perhaps even some staged lighting to have a dawn dusk effect. If you give me a run down on the best kit to set up this king of tank what type of filtration, lighting, circulation and planting I'd be very grateful. Also should I go for a second juvenile and hope they grow up happily with one another, or is it better to stick to the one fish? < These are really cool fish. Unfortunately they are nocturnal and only come out at night or at dusk. They stay away from bright light. You might try red incandescent bulbs to observe them at night. They prefer clean soft acidic warm water and live food. They are prone to come down with ich and are difficult to treat. This could be because they are rarely seen by aquarists and  are often diagnosed too late. They like lots of shelter during the day so caves and logs are appreciated. Years ago they made " Black Ghost Houses" which were nothing more than clear plastic tubes with little feet on them. This way the ghost thought it was hiding. I don't know how well they worked or if they still available any more. These fish really don't see that well and get around by using a week electrical field like electric eels to get around. They get up to 18 inches and are being bred in Thailand.-Chuck> Kindest Regards, Carraig Tuomas

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

Black Ghost Knife / Filter Contamination   9/4/07 I'm an intermediate fish keeper, have been doing it for a few years (beginner still, I suppose). Started with 5 gallon, then 20, and now a 72 bow. It has a wet/dry filter a temperature of about 81 degrees, and as far as water quality, I haven't read ammonia, nitrite, OR nitrate in the past 6 months, and a PH hovering between 7.8 - 8.0. It's fairly established, maybe 9 months old, tropical community. <All sounds very promising.> I recently purchased 2 Black Ghost Knives (BGK) fish from my LFS, and added them to tank (yes, I know quarantine should be done, but college has me on a nickel-dime style budget). <Ah yes, I remember those college days well!> The fish (perhaps 4 inches) seemed very content, swam happily, found hiding amongst rocks and water lilies, and came out at night to feed. None of the other fish were aggressive towards the knife (with possible exception of Zebra Danios, but they stay topside, and vice-versa for BGK). <OK.> After two days, I had the lovely sight of coming home to one of my BGK's stuck to the strainer on the overflow... lived through that, but died soon thereafter (my fault, water flow rate has been adjusted accordingly, they won't get stuck now). <This doesn't sound like cause and effect to me. Apteronotus live in big river systems, in quite deep water. It seems unlikely to me that a filter could create too much current for this sort of fish. Usually, when someone finds a fish stuck in the filter, the fish died, or was weakened, and the filter merely dragged the body towards itself. A healthy fish should have no problem avoiding a filter.> That death I can understand. <I can't.> Five days later, I wake up to see my other BGK lying on the sand (dead, of course). <I see. Now this sounds as if you have two cases of Apteronotus death, with the filter implicated just the once. This reinforces my opinion that the filter had nothing to do with death #1.> No visible signs of biting or otherwise aggression related harm. I'm totally stumped. My question to you is this: Could the slightly high pH of my tank have slowly killed him, or could it have been something else? I'd like to get another, but I want to be sure of the problem on my end (if there is one) so I can fix it, thus avoiding an unnecessary death of a beautiful fish. <Apteronotus are not easy fish. They are incredibly sensitive to water quality. In terms of water chemistry, they aren't especially fussy (Fishbase reports pH from 6-8, 5-19 dH) and comparable to most other South American tropical fish. So your pH/hardness issue is unlikely to be the cause of death. The exception here would be if the water chemistry *varies* a lot. But provided it was constant, even a relatively high pH shouldn't be a problem. (This is true for most freshwater fish in fact: steady water chemistry is more important than clumsily going after some mythical "optimal" values.) So, here's what I'd be investigating. Firstly, is your water chemistry very different to that in the store? For example, do you soften or acidify the water, or add peat to the filter. Secondly, what scale/frequency of water changes do you do? Weekly 50% water changes should prevent the inevitable background pH change in all aquaria from becoming significant. But if you do small water changes, say, 20% every couple of weeks, then the pH could drop in the aquarium over the two weeks, and then rapidly go up when you add new water. This would be bad. Thirdly, I'd be testing for nitrite across the day, maybe three or four times. Sometimes, tanks develop nitrite problems shortly after feeding, but seem to have zero nitrites at other times. Spikes in nitrite concentration would be lethal to something as sensitive as Apteronotus. Fourthly, are you adding anything to the water (other than dechlorinator, naturally)? Some benighted folks go round adding stuff like salt and anti-stress medications on a weekly basis, and while hardy tropical fish shake off these misguided annoyances, Apteronotus will not. While we're on the topic of dechlorinator, make sure yours removes chloramine, if you live in an area where chloramine is used. Finally, did you add any medication? Apteronotus are intolerant of many commercial brands of things like anti-whitespot medication. If you used these in the recent past, adding some carbon to the filter for a few weeks might be a good idea.> Any help is greatly appreciated! <Done my best!> -Brandon <Cheers, Neale> (thought of another question, couldn't get a straight answer elsewhere) <OK.> In my 72 gallon tank w/ overflow and wet/dry filter, I use a filter pad that claims to be re-usable with cleaning. It's instructions for cleaning are to soak 1 part bleach w/ 10 parts water overnight, then rinse, then soak in plain water overnight again. Is this adequate to rid the bleach? I've had some strange occurrences lately (mollies dying, no reason) given my water quality is good (0, 0, 0, pH 7.8 - 8.0, 81 deg.), and am starting to think it might be bleach contamination. Just curious on any insight or special tricks to know when the bleach is chemically gone, not just sensibly. Thanks! -Brandon <Agreed, this sounds like a dumb idea, so not sure why the manufacturer are recommending it. If you need to wash something, hot water should work fine. Sometimes I soak things in brine if these need a deep clean (e.g., it's an ornament I left out in yard over winter and its covered in mud and slime). Once you rinse the thing off, any traces of salt will be harmless. It is entirely possible traces of bleach have irritated your fish, leading to death. So, stop doing this. Clean the filter the old fashioned way (in buckets of aquarium water) and then replace sponges when they are so clogged they can't be cleaned any more. NM>
Re: Black Ghost Knife / Filter Contamination 9/5/07
Thanks for all the info on the BGK! <You're welcome.> I do bi-weekly changes of about 20%, so I would assume from your reply I should be doing something more towards 40% on a weekly basis? <More like 50% for something as sensitive (and big) as Knifefish.> (Sounds like a lot of water, closing in on 30 gallons). <Them's are the breaks.> I use a product called "Prime" to treat incoming water, as well as some time (chlorine has a slight evaporative property if I recall correctly). <Absolutely DO NOT rely on chlorine evaporating. Use the full dose as stated on the carton, and stir well. Also, if your local water board uses chloramine, that won't evaporate.> I will begin more thorough logging of pH and nitrite for a two month period or so, to see average variance. <Very good.> In summary, I suppose, a 30-40 (even 50) % water change weekly would maintain a stable pH for my tank, and not be detrimental to the fish at the same time (in terms of massive quantities of water coming in and out on a regular basis)? <Assuming you do the water changes regularly, the dilution effect will mean the pH/hardness in the aquarium will be approximately equal to your tap water supply. A week isn't long enough for the pH to drop much. The main thing is to check temperature of the new water matches the old, so that there isn't a huge temperature drop when you add the new water.> It probably was the pH, because now that I think about it, I changed 13 gallons of water the day before he died... <Sounds like clutching at straws. What makes you think the pH changed? What's the pH of the tap water, and what's the pH in the aquarium? Water changes where the pH/hardness are the same in the old water and new water DON'T DO HARM. That's old school fishkeeping. Nowadays we've learned new water is best, and some people even do 90% changes per day!> I'm so sorry for all of the questions, but I care for my fish more than most people, and I want to do everything I can to ensure their good health. <Very good.> In regards to the filter pads, the problem with just washing with aquarium water is that it won't clean it well enough. <Get over it. Biological filter pads don't need to be deep cleaned. All you need is to rinse off the worst of the silt. So, don't EVER wash biological filter pads in anything other than aquarium water. For the mechanical filter pads, deep clean with hot water, or else replace with new ones. Now, this said, if your filter is getting so dirty the pads are irretrievable, then you are either cleaning the filter too rarely OR you have too small a filter for your aquarium. Under normal, correct use a filter should only need cleaning at most once a month, and even then the sponges should be easy to clean in buckets of water.> I set mine up as two-stage filtering, first is a large plastic pad (kind of like a scouring pad) to catch large debris (and the occasional small fish). <????> The second one (which is bleach cleaned) is a 100 micron pad, looking more or less like felt. This makes for remarkably clear water, but the downfall is that they needeth be changed every three days at best. <The second filter is the biological filter. You absolutely should not be cleaning this in anything other than aquarium water. Your filter sounds basically inadequate, and almost certainly not removing nitrogenous waste quickly enough. And that's why your Apteronotus died. Until you create and mature a more reliable filter system, don't buy any more fish> At $20 for every 9 of these, it can add up. Bleach cleans them wonderfully, but I suppose if it's hurting my fish I shall find another way. <Indeed you MUST. Please read the articles here at WWM on filtration. I'm not convinced you understand the theory and practise yet. You shouldn't need to replace filter media more than once a year, and I don't replace biological media for periods of 5+ years at a time. If you're finding your filter media completely clogged up and useless before then, you have a problem.> I much appreciate your help, and in a few weeks, maybe a month, I'll take another shot at a BGK, and I will be sure to let you know of the happenings of him/her). <No! It will take 6 weeks, minimum to mature a biological filter to the point where it is stable. Since Apteronotus don't do well in "new" aquaria, I'd not expect to keep one safely for at least another month or two after that. You need to review your filtering system. Minimum, it should provide 6 times the volume of the tank in turnover per hour (i.e., for a 55 gallon tank, the filter should be rated at around 330 gallons per hour). The filter media should stay so clean that you only need to rinse them off every 1-2 months. If you don't have these things, you don't have a system that can contain Apteronotus albifrons. Buy another one... and it'll die.> -Brandon <Good luck, Neale>
Re: Black Ghost Knife / Filter Contamination 09/05/07
Again, thank you in kind for the help! <You're welcome.> My tap water has a pH of about 8.0. <Admittedly not ideal for this species. But not toxic, either.> Prime removes chorine and chloramine. I mix water with powerhead in large plastic tub with its own heater and digital thermometer to make sure it's within 0.2 degrees of tank. I can deal with lots of water usage, lives are at stake here ;-). <It's not so much that, as the fact doing a 50% water change compared with a 20% one really isn't that much work by the time you have the buckets and hose pipes. So you may as well do a big water change and improve water quality while inhibiting background chemistry changes.> Best thought about pH being cause of death (more likely TDS or dH) is that I had gotten behind on water changes (school starting, personal issues, etc..) had been maybe a month. I can imagine pH could have dropped enough to cause a shock to a Knife when higher pH water was added. <Indeed. That's why we need pH test kits.> The filter pad in question is not the bio-filter. It's a mechanical pre-filter for a 75 gallon wet dry filter with a 700gph pump (which probably puts out more like 500 with head and friction loss) = ~ 6-7 times turn over rate in tank (on full flow - have a diverter to pump part of flow right back in sump if flow need be slowed down - doesn't restrict flow from pump, but does to tank). Will probably switch back to a more conventional pre-filter (i.e. floss pads or similar) to alleviate consistent changing of micron pad (which was every 3 days). These are easily replaced, so no need to clean, right? Biggest thing that clogs micron pad is plant matter (tank is planted, and a Geophagus brasiliensis enjoys digging them up/ chewing off bits of plants). Tank is established (in my mind, at least) being almost a year old with no traces of ammonia, nitrite, or nitrate in the past 6 months. The bio-balls never clog, but the mechanical pre-filters do in time, from said plant debris. I think you simply misunderstood my filter type, perhaps thinking I had a large power filter or something similar. The wet/dry is marvelously efficient for freshwater from my experience. <Agreed, these filters can be very good. If the pre-filter is clogging, then just use something cheap instead of the expensive units supplied with the filter. Ordinary filter wool should work, no? Alternatively, clean the pre-filters much more often, every couple of days if required, just rinsing them under the tap.> I also enjoy very much reading your site, I spend a good hour a day, 5 days a week on here trying to learn more. <Glad you enjoy.> Anyways, I will try the larger volume water changes and see how it works with current fish, and continue to test pH (and possibly carbonate hardness and TDS...read up on those, apparently too many TDS can cause a difficulty for fish's cells absorbing the diffused oxygen in the water, and as for the hardness (if I read correctly) if the hardness is maintained, the pH will be less likely to change, hence providing a more stable water chemistry, which is the overall goal here). <In theory, yes, TDS (total dissolved solids) is related to osmoregulation. BUT, once a fish is acclimated to a certain TDS level, sudden changes, even towards "better" levels, can be bad. So it's better to have a fish acclimated to the "wrong" water chemistry but maintaining very stable water chemistry and quality, than trying to force your tank to the "right" water chemistry while bouncing around pH/hardness in the process and skimping on water changes because of the expense. In other words, don't fixate on the value so much as the stability and quality.> I am greatly in debt to your help, and am hoping to learn how to maintain a VERY stable water condition, because I am very bent on being a successful BGK keeper (saw a nice 75 gallon tank the other day, would make nice home for a few years for him... till he got bigger, that is). <There's no secret to stable water conditions: big tank, under-stocking, good filtration, and above all, large and regular water changes. Likewise, the causes of unstable conditions are well known: too many fish, lots of organic decay (plants, general muck), clumsy manipulation of water chemistry through use of peat or buffers, and infrequent water changes. So, do the first list of things and avoid the second list, and you're laughing.> Hopefully I can apply everything I've learned from you and this website to make it happen. Thank you more time! -Brandon <Glad we could help. Good luck, Neale>

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