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Black Ghost
Knifefish, Apteronotus (Sternarchus) albifrons, Behavior
Related Articles: New World
Knifefishes, Gymnarchus, Notopterids/Clown
Knifefishes, Electrogenic
Fishes,
Related FAQs: Knifefish
Behavior,
BGK FAQs 1,
BGK FAQs 2, &
FAQs on: BGK ID, BGK
Compatibility, 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...),
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Listless Black Ghost Knife
5/10/09
Hi Guys
<Hello,>
I have read through your site (which is fantastic btw) and have been
unable to find anything similar to what I am experiencing.
<Oh?>
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!
Regards,
Marion
<Good luck, Neale.>
Re: Listless Black Ghost
Knife 5/10/09
Hi Neale
<Marion,>
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.
Regards,
Marion
<Cheers, Neale.>
BGK playing dead? 4/4/09
i
<I>
have had a BGK for almost a month now, introducing it to a tank that
previously and still contains 2 angels and a Pleco...i had a Gourami,
not sure as to what species as i am totally new to this , it
mysteriously
died...maybe overfed cuz it ate EVERYTHING. Then introduced a FW
flounder
<Hard to keep>
4 platies 3 of which were pregnant, and a single Kuhli loach (i know i
need more, but the store i got him from only had 2 and i didn't know
much about them, and they don't get more till this Monday and they are
absolutely awesome fish XD).
<XD?>
Yes i understand the BGK is definitely not a beginner fish, but its been
perfectly normal, and I've learned so much from this site...only problem
I've had with my BGK is its trick which is discomforting..."playing
dead" or taking a nap, this started just under a week ago and has become
more common idk if its a problem or not i just don't like it. I will
live with it if it is not a problem though. I know it is nocturnal and
usually is
seen feeding only at night
<What they do>
and it has a "Ghost house" tube to hide in, but i will move that out of
constant light, another fine fishy fact i learned from your wonderful
FAQs.
He usually eats live brine shrimp and halved cubes of frozen (by the
time i get them to him thawed XD) bloodworms and maybe my first pregnant
platy =/. Unfortunately seeing as this is my first tank the only info i
can give is that it is a 30 gal tank and is usually above 75 F, and
usually crystal clear but not so recently. Please respond with the best
of your knowledge as always, Ken
<The "playing dead" behavior is normal for freshwater Knives... Bob
Fenner>
Strange BGK behaviour
8/6/08
Hello,
I have a young BGK (about 4cm long) that is exhibiting strange behaviour.
I'm Australian, so please forgive my metric measurements.
<Not at all! I for one prefer metric measurements...>
I have a 160L tank, the water temperature is 27 degrees Celsius and the PH
is approximately 7.2.
<Long term this tank is way too small for Apteronotus albifrons, though
right now there's no harm, and won't be until the thing gets to around ~20
cm.>
There are 8 Neons, one dwarf Gourami, one flame Gourami, one bristle nose
cat fish and two snails.
<Hmm... long term the Neons will of course be at risk of being eaten...>
The knife fish appears to be rubbing itself against objects such as flat
rocks and plants in what I would describe as a fish that appears to be
infected with Ichthyophthirius multifilius.
<Certainly possible, especially if new fish have been added to the system.
Treating with heat/salt isn't a bad idea (raise the temp to ~28-30 to speed
up the life cycle, and raise salinity to 1 gramme salt/litre, though add the
salty water in stages across a few days so as not to shock the fish.
http://www.wetwebmedia.com/FWSubWebIndex/fwich.htm
Apteronotus albifrons is sensitive to some medications, so I wouldn't
necessarily go with standard copper/formalin treatments.>
However, there are no physical manifestations of this disease and the fish
has a healthy appetite for it's diet of blood worms and does not show any
other signs of weakness, immobility or discolouration.
<Sometimes Ick and Velvet go for the gills before the skin/fins, so not
seeing the white spots doesn't always mean much. Still, if the fish is
infected you should see the white spots appearing eventually. The salt
treatment won't do any harm. I'd also check the water quality/chemistry --
fish "flash" when irritated by ammonia/nitrite/pH changes, and Apteronotus
is much more sensitive than the other species you have. If the other fish
don't show any symptoms that would suggest Ick or velvet, I'd definitely be
worrying about environmental issues.>
All other fish appear healthy, happy and disease free. I owned a BGK about 7
years ago, but I do not recall it behaving in this manner. Any advice would
be appreciated. I hope I'm not being too paranoid.
<Ah, no, paranoia with this species is well placed. Extremely sensitive, and
one of the more difficult to keep fish in the hobby.>
Thanking you in advance,
Janine
<Cheers, Neale.>
Re: Strange BGK behaviour
8/6/08
Hi Neale,
<Janine,>
Thank you very much for your advice and quick reply. I was thinking about
initiating the salt/heat treatment as I don't like introducing chemicals,
but I have never done this before so I wasn't really sure how to go about
it. Hopefully I've caught it early enough.
<Fingers crossed!>
Thanks again,
Janine.
<Most welcome. Cheers, 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.>
Freshwater fish electro-sense question
I recently bought an elephant fish. today my girlfriend surprised me with a
black ghost knife. They are both about 3in and are in a 34 gallon tank with
separate very good hiding spots. Will there 'electro-senses' clash?
<There have been some studies on these electromagnetic fields generated by these
fish but not much in the popular aquarium literature. But I am sure that they
are aware of each other.>
also how sensitive are they to salt?
<These fish come from clean warm acidic water and have become very sensitive to
salt.-Chuck>
I use a little less then the recommended dose of aquarium salt(1tbsp per 5
gallon). tank also includes 6 glass cats and a blue lobster.
thanks for your time.
-Zac
Ghost Knife Turned cream
I have had my beautiful Ghost for over 8 months. He's only about 5 inches
long. Recently I have noticed, that he has turned a very pale shade of
light tan.
<be sure to check to see if his skin is turning the color, or does it appear
to have a "dust" like coloration to his body. It might be Oodinium
(otherwise known as velvet). The visible symptom of this disease is a fine
grey-gold to whitish 'dust' on the body of the fish. Fish will usually show
very rapid gill movement during this time. The disease is caused by a
protozoan parasite, and may be triggered by exposure to ammonia and
nitrite, or excessive nitrate levels. That is if it appears to be something
on the skin. I've never heard of a ghost changing his color before. Have
you checked his water parameters lately? Make sure that the ammonia levels
aren't that high. and be sure to keep up on the water changes. If the fish
isn't showing any signs of stress or sickness then I'm not sure what is the
best course of action to take. I wouldn't want to add a medicine to the
water and stress it out if it's not needed.>
Nothing has changed in the tank-no new fish added, etc., so I don't know why
he would be stressed. He still bobs to the top to eat. Have you ever heard
of this?
<I haven't heard of this happening with a ghost knife, I would keep a close
eye on him and make sure if you start to see any problems, or if the fish
starts rubbing itself on objects in the tank to move it to another tank and
start medicating it accordingly.>
Ren in Montana
<Good Luck with the fish. -Magnus>
Off-colored Ghost Knife and Oscars with Angels - 02/22/2004
Magnus...
<Sabrina, today, hope all is well>
Thought I would update you on my ghost who lost his color.
I put him in my 5gal guppies tank. Thought that would be best - no one to
intimidate him. Of course, he loved the old car for his home, and as expected,
the baby guppies all disappeared. Had to make a decision of sacrifice to
hopefully keep him alive. I noticed a bit of black coming back (due to fresh
"sea food" I'm sure...),
<And you'll surely have more baby guppies in the future, no worries. Good that
they have contributed to your ghost's well-being, a worthy cause, IMO.>
but he has outgrown the little tank,
<Heh, to be expected!>
so I moved him to the 38gal. This tank consists of Parrots, Tiger Barbs, and a
handful of misc. The red tail shark is probably the most aggressive, but lives
in harmony with the others usually. Once in awhile he'll chase the barbs
around. So far the ghost has found an ornament to hide in and seems to being
doing okay.
<IMO, all of these are too aggressive as tank mates - do keep an eye on him,
watch closely for splits in his fins or any other signs of distress.>
Another question....I have a 60gal octagon with two Oscars, two tins,
<Hmm? Ahh, tinfoil barbs, yes?>
two fire mouth cichlids and two angels and a silver dollar. All is well with
the combination at this point, but as the Oscars grow (one is about 6"), do you
think the angels will be okay?
<Not at all, not in this size/shape tank - I would consider all tankmates
grossly at risk of harassing/harming one another as they "grow up" - the Oscars
will likely require a tank of their own, if they're getting on well, they've
likely paired. Removing them to their own space will give you some wiggle room
for the rest, and the Tinfoils are the next biggest worry - topping out at about
fourteen inches. Fortunately, they are durable, and slow growers - I would
remove them with the Oscars. A tank that is big on surface area (er, not a
hex/octagon/tall tank) will do best for the four.>
One angel is quite large, the other only about 2 1/2 inches. I know there is
not always a rule to go by, but do you
think I should move the angels?
<The Oscars and Tinfoils will need a larger tank in the long run.... not so much
larger in gallonage as in usable space.>
FYI-my "herd" has gone down in numbers. I have been very blessed to have had 6
adoptions in the past two weeks.
<Wonderful!!>
Down to 13 dogs-seems so quiet.
<Sounds like you're doing quite well.>
Thumbs up to your girlfriend for helping the shelters and rescues-wish she was
here!
Have a wonderful day. Ren
<You, too. Wishing you well, -Sabrina>
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Black Ghost Knife habits
Good day,
I am writing to ask about the black ghost's behavior.
I notice that sometimes it lays on its side in the Mondo grass I have in my
tank. Is it 'sleeping'? Or is it sick? I have never had a black ghost until
my brother bought one for my birthday the other day. any answers would be
appreciated.
< The black ghost is really a cool fish. Unfortunately it is nocturnal and is
rarely seen during daylight hours. If you really want to see him out and about
then you can turn off the aquarium light and feed the tank some black worms or
live brine shrimp. Just use the room light to watch him. In bright light they
will hide in logs or caves until dusk when they come out to feed. They get big,
up to 18 inches but got to be up there as one of the strangest aquarium
fish.-Chuck>
Thank you!
Eric
Training a black ghost knife fish 9/22/05
Dear Mr. Fenner,
I have a black ghost knife fish that I have had for a month. He is now about 7"
long and very healthy. He eats flakes in the morning and at night,
occasionally I give him some freeze-dried Tubifex worms. What I would like to
know is how you teach them to eat out of your hand. He seems to be a smart one
he figured out the flakes were edible on his own. If you know how to do this I
would really appreciate it.
Thanks for your help,
MDM
<Try feeding small amounts of meatier foods, more frequently, particularly just
with some light on outside the tank (not in... too bright). Takes time,
patience. Bob Fenner>
FW algae and Apteronotus skin
Hi, In my 29 gallon tank there are re-brownish specs on everything. My water
parameters are fine and I do weekly water changes and cleaning. what do you
think it is?
<Almost undoubtedly algal colonies... take a read on WWM re>
Also I have a Black Ghost Knife for about 10 months now and since November
he has shown a weird green/brown gel-like coating over him. I thought it was
ick but wouldn't have died by now if that was the case. Do you know what it
is and how to treat it?
thanks.
<This is probably the animals skin itself... and your good vision. The
species is "quite slimy" in good health. Bob Fenner>
FW algae and Apteronotus skin, II
Bob,
thank you for the response I just wanted to add that my knifefish's slime is
a little whitish-gray when the aquarium light is on, does that make a
difference?
<Actually, yes... as stated, you have excellent vision, observation>
I mean when I go to the pet shop all the ones are pure jet black.
Jahner
<These are more stressed... Bob Fenner>
BGK suddenly shy
11/12/07
Hello Crew,
I've had a BGK for 8 months now.
He lives in a 55 gallon tank with 2 clown loaches, 3 discus, 2 rams, and a
golden nugget Plec, with loads and loads of plants.
I do weekly water changes, and water conditions are almost perfect. ammonia 0,
nitrite 0, nitrate trace. People always comment on how crystal clear my water
looks.
He's been very healthy and happy, and growing slowly.
There are several hiding places for him but he has taken up home with the 2
clown loaches in a black tube.
<Predictably>
The three of them swim about looking for food during the day as well as when the
lights go out. As soon as I drop food in, those three
are the first on the scene playing with each other and eating as fast as they
can, its so cute to watch.
<Ditto>
But in the last 3 weeks or so, the BGK has stopped coming out. He just stays in
the tube wiggling about.
At feeding time only the loaches come out. I'm very careful with over feeding so
the food I put in is always all gone
within ten minutes. So I'm 99.9% sure the BGK hasn't eaten in 3 weeks!!
<Mmm, is eating something, assuredly... Perhaps you have other food... live
worms and such, living in the gravel at this point>
Is it normal for these fish to suddenly change their behavior?
<Does happen>
Today, I fed my discus live bloodworm as a treat, one worm landed in front of
the hiding tube and the BGK stuck his head out ate it and went back in.
My question is, how could a friendly full of life BGK suddenly become a scaredy
cat? there has been no changes, no new tank mates, no change in feeding
schedules.
My tank is always in view, and he never comes out, day or night.
Can there be a chance of illness with him? What can I do?
thanking you in advanced
Freddie
<If I had to guess... I'd say that the most likely possibility is that your
Discus are getting larger, perhaps showing a bit of aggression toward this
Apteronotid... Do try to spend a bit more time in front of the tank to
observe... If two do pair off, there may be trouble for all the other fishes
here. I might try some cultured black worms (tubificids) to urge this Knife's
return to feeding. Bob Fenner>
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