FAQs on Black Ghost Knifefish, Apteronotus (Sternarchus) albifrons,
New World Knifefishes,
BGK FAQs 1, & FAQs on:
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
NOT w/ mean fishes, nor ones that will outcompete it for
Black Ghost Knifefish Compatibility Question, w/ Fire Eel
I have a 125 gallon tank that currently houses my
7 inch Black Ghost Knife Fish and 2 Bristlenose Plecos.
I recently upgraded the filter on this tank to a Eheim Professional 3
(rated for a 300 gallon tank),
it has sand substrate and lots of big caves (4 inch PVC pipes) for
hiding. I also have a friend who purchased what he was told was a Spiny
Eel from one of the big chain pet stores only to find out it is
actually a Fire Eel
<Mmm; Fire Eels are Spiny Eels; that is, Mastacembelus erythrotaenia are
part of the family Mastacembelidae>
that has attained a length of 7 inches in just 3 months.
<Ahh; and can grow to a few feet in length; most mastacembelid species
stay under a foot>
He only has a 40 gallon tank so he wants to rehome the Fire Eel and
asked me if I wanted it. I did some research and got conflicting
opinions as to whether these two species would be compatible (the
naysayers believe the Fire Eel would eventually eat the BGK). However,
the individuals who believed they were compatible also posted some
beautiful pictures of these two species interacting well with each
other. I had planned on upgrading my BGK's tank in the next couple of
years and have already purchased a stand for a 180 gallon tank (but I
don't have the tank yet). So, I would really like to hear your opinion
of keeping these two species together.
<I do think the two can, will live together for a good long while. Fire
Eels do get large (enough) to consume fishes, but by being careful not
to "feed for growth", yours can live for a good long while with the
Knife. Bob Fenner>
Re: Black Ghost Knifefish Compatibility Question
Yellow weather loach w red areas on body
Very concerned. Loach has red areas, first near tail, now half of body
after severe stress w tap water high in ammonia (4 ppm) w me not finding
<Aye; deadly toxic; likely the principal source of trouble here;
particularly in more alkaline water ammonia is very dangerous>
Several days of frequent water changes, some lost fish, other parameters
normal to tank, but very hard to get ammonia down....added prime often,
know this detoxes but doesn't remove. Thus not sure exactly how bad in
actual tank. Purchased spring water for changes.
Now loach has red areas, very inactive, sure he doesn't feel good.
Don't know how to help him or if euthanasia is best. Really like this
guy, hate to see him suffer.
<Am a laggard in terms of euthanizing livestock that has a chance to
recover. This loach species is very tough>
Had an ammonia spike a few months ago, managed to save everyone. This
time more severe.
Please help. Larry is a friend. About 1 yr old, 7 in long.
<Do take a read over our archives on Dojos:
and the linked files above. DO what you can to get rid of the ammonia.
SEE as in read on WWM re; chemical filtrants are the route I would go
NOW. Bob Fenner>
Re: Got My First BGK; multiple Mormyrid stkg.
If you can stand yet another question from me, I was hoping you could
clear up some information (or, possibly, misinformation) I found on the
I have read that you cannot (or at least should not) keep more than one
mormyrid in one tank.
<Does depend on the species. Some are quite sociable, and do well in
groups of 6 or more specimens. Indeed, most of them probably are social
in the wild, certainly the class Elephantnose seems to live in big
schools, but the sheer size of the standard Elephantnose makes this very
difficult to accommodate at home. Singletons can do well, becoming
fairly tame if looked after well. A big group should be fine too, but
unfortunately in twos or threes they tend to squabble unless the
aquarium is very large, so they're rarely kept in groups outside of
They say that the electrical impulses these fish use to find food would
conflict and potentially cause both fish to starve.
<Correct. Dominant specimens hog the best frequencies, forcing weaker
specimens to use less effective ones, making it harder for them to
navigate and find food. Not a problem in the wild where a big school of
them couldn't be dominated by a single specimen for any length of time,
but in the aquarium, it can be a bully's paradise with so little space
available for weaker fish to move out of trouble.>
I have no intention of getting any more BGK's, but I keep thinking about
the little Elephant Nose. I'd love to have one, and their water
parameters are consistent with the BGK, but I don't want to cycle up
another tank right now.
<I would not mix Elephantnoses and Black Ghosts in the same tank, at
least, not without a Plan B if it turned out the two species didn't get
Also, I'm concerned that because the BGK comes from fast moving waters
and the Elephant Nose lives in slow moving water, that the Elephant Nose
would suffer in the same tank.
Again, this is not something I plan on doing in the near future as I
have my hands full with the BGK. I guess you could say I'm just starting
<Do review some of the smaller, more sociable members of both these
groups. The Glass Knifefish (Eigenmannia virescens) for example is
fairly widely traded, and small enough that maintaining a group in, say,
a 55-gallon tank
wouldn't be impossible. Such a species could cohabit with tetras and
catfish, if all were chosen with care. Similarly the Baby Whales
(various Pollimyrus and Petrocephalus species) are smallish relatives of
the Elephantnose that are viable in groups if you have the space.
Re: Got My First BGK 5/1/17
Thank you again! But I've got my heart set on an Elephant Nose.
However, given your advice, I think its best that I just focus on the
BGK for now and put off getting the Elephant Nose until sometime in the
future when I'm able to set up a tank just for that fish.
<Wise. Although good community fish in the sense of cohabiting well with
small African tetras and the like, their special food requirements do
mean they're poor choices for rough-and-tumble set-ups alongside species
non-herbivorous catfish and loaches that might compete for food. They
can be picky eaters, but not excessively so, and will adapt to a range
of foods. I memorably saw an adult specimen consuming vast quantities of
baby brine shrimp!>
Thank you so much for all you do!
<Most welcome. Neale.>
Black ghost knife - quarantine and tank mates.
I'm finally setting up a tank for a black ghost after waiting for almost
8 years :D starting it out with a 60 gal tank, slightly planted.
<Sounds good, though 60 gallons will be small for the size of adult
So be aware, at some point a bigger tank will be necessary -- if all
goes to plan!>
I've read up most of the information available on the internet regarding
to these fish but since they're very sensitive to medications i wasn't
sure about how to go about the quarantine process like what all to treat
it with, dosage and for how long.
<Basically, don't medicate; isolate. Keep the Black Ghost Knifefish on
its own for 6 weeks. In that time, if it shows any sickness, use very
specific treatments. Antibiotics for bacterial infections, salt/heat for
That sort of thing. Avoid "general cures" like Melafix, and definitely
avoid anything containing copper or formalin, both of which are
extremely toxic to these fish. Medicines described as "safe for
cartilaginous fishes" such as sharks and stingrays should be safe to
use. Your other challenge is to get your Black Ghost Knifefish feeding!
You want a wide variety of foods, not just bloodworms. The bigger the
range of different things your Knifefish will eat, the better. More
small meals per day is better than one big meal. Most of all, you want
your fish to have a nice rounded belly, not
swollen, just gently rounded. Such fish will be healthy and putting on
weight. Once you're sure your Knifefish is feeding well, you can then
add tankmates, ideally non-bottom feeders (like Angels) first, and over
the months, other types of fish (like the loaches) that might compete
coming to tank mates i was thinking of :
1 Senegal bichir or an Albino Senegal bichir ( which would you
<Good choice. Very similar in temperament, but Bichirs are sold at
bigger sizes, so I'd get the Knifefish settled and feeding first, for a
few months ideally, then add the Bichir.>
4 yoyo loaches
<Also good, provided they don't eat all the food.>
a couple of silver angel fish
also i got a electric blue Dempsey recently. still a baby about 2 inches
and i was wondering if he can be kept with the BGK. sounds risky but i
did read in a few places that only one can be kept successfully in a
<I would not keep a territorial, aggressive cichlid with a Black Ghost.
Juvenile Black Ghosts are very delicate and slow feeders, and you'll
find most cichlids cause them stress. Adult Black Ghosts are a bit
tougher, but still, not worth the risk.>
Thank you so much in advance,
<Most welcome. Cheers, Neale.>
Re: Black ghost knife - quarantine and tank mates.
Thank you for such a quick response :)
I'm planning to get a 150g set up by the time he hits 8-9 inches.
About the antibiotic, will erythromycin be fine?
<Can work, but bear in mind Erythromycin works only against some
also should i stick to half a dosage recommended? cause' I saw a couple
of videos where it suggested to stick with full dosage as half a dosage
might not help with the issue and might make the fish resistant to the
<Absolutely! Unless a doctor or vet tells you to reduce the dose, use
the full dose. Your research is absolutely correct in that half-doses
(and not finishing the whole series of doses) can lead to antibiotic
resistance. And that, as you know, is VERY bad.>
Also the other thing i was a little worried about was the ph. The tap
water ph here is about 7.4 which is generally high for them. But im
caught up between setting up the tank with a lower ph water or get the
fish acclimated to the tap water ph? I'm guessing the lfs here also have
the same ph. I'm torn between giving them the ph they're supposed to be
giving them a consistent ph.
<Water chemistry is not too important. Medium hard water up to pH 7.5 is
fine. Black Ghost Knifefish are MUCH more sensitive to poor water
As for the food, I thought I'd start him off with Hikari carnivore
pellets then slowly bring him up on fresh food like earthworms, shrimp
and tilapia once he gets to a reasonable size. also your thoughts on
Spirulina for bgks? and vegetables like cucumber and spinach. Some of
the things i came across while looking into the food.
<Try everything! Variety is CRUCIAL. If your specimen likes Spirulina,
then great! They are micropredators though, so Spirulina-enriched frozen
brine shrimp will probably be the easiest way to get "greens" into your
Black Ghost Knifefish.>
would you recommend mixing the antibiotic with food or dosing the water?
<Giving in the food is ALWAYS better for systemic bacterial infections
(like simple failure to thrive). But adding to the water is probably
just as good for treating external infections like Finrot. Adding to the
water tends to be hopeless for systemic infections though. So as we say
in England, "horses for courses" -- you identify the situation you're
choose a dosing method as required.>
And the juveniles we get around here are about 2-3 inches, is it okay to
get them or should i go for a slightly bigger one?
<Ideally, yes; very small fish (relative to adult size) tend to be
rather delicate. The ideal specimen is probably around the 12-15 cm/5-6
inch mark... but MUCH more important than size is how well fed it is
(and how aggressively it feeds!) when you see it in the shop. A small,
but pushy, fish that's happily eating lots of food will be much better
than a bigger
fish that hasn't eaten for weeks. Make sense?>
I'm tempted to get a smaller one cause' I want to see him grow from a
tiny little spec to a massive fish.
<They grow ever so slowly, so this can take a while! In fact hardly any
reach adult size because not many people keep them for anything like a
normal lifespan. I've seen one or two adults over the years, and they're
massive fish! But most people buy youngsters that live for a year to two
before dying for some reason -- usually lack of food (they have BIG
appetites) and/or poor environment (they need lots of space/lots of
Thank you so much again.
Re: Black ghost knife - quarantine and tank mates.
Thank you so much for helping me out last time, so as per the advice on
the quarantine process for the black ghost,
I set up a 20 gallon so its easier to keep an eye on fish too see if its
feeding and excreting properly.
But i noticed that my tap water ph is about 8.2. I know this is too much
for bgk, but is it possible to acclimate it to this ph?
<Yes, but unwise if you aren't changing hardness as well. It's the
hardness, not the pH, that causes problems for fish.>
I did read in a few webpages that it is possible but, i wasn't
comfortable to trust that hence asking you. I cannot afford to get an RO
system installed right now. I'm still a student. The only other way is
to get canned drinking water, but I'm afraid it wont be available in
<I would not worry too much. I would focus on water quality and diet.>
Now i could decrease the ph of the water with driftwood and almond
leaves, but I'm worried about the ph swing during water changes.
<Indeed. A slight and slow pH drop between water changes won't be too
bad, provided you do small water changes periodically. But you would
have to measure pH regularly, probably several times a week for the
first couple of
months, until you had a good idea of how pH changed (if at all).>
The other thing I thought of was, setting the tank up with the
canned/drinking water (ph of about 7.4) and doing a 10% water change
twice a week with normal tap water. would it still be a huge ph swing?
will this work?
<It's not a bad idea at all! Set the tank up with your tap water first.
Then over the next few weeks, make small changes to water chemistry by
doing 10% water changes every few days, even once a week. See what
So long as hardness isn't lowered to zero, and pH doesn't fluctuate
wildly, you'll be okay. Put it this way: do a water chemistry test on
your drinking water. Let's say it's 5 degrees dH, pH 7.4. Then you test
your aquarium water, and it's 20 degrees dH, pH 8.2. If you mix the two,
50/50, at each water change, you will eventually end up with a tank
around 12 degrees dH, pH 7.6, which would be absolutely fine.>
I'm reconsidering getting the fish and its breaking my heart. But I'd
rather not get it than make it struggle in a high/unstable ph.
<A high pH is not necessarily a deal breaker; but an unstable pH is. See
above. If the Black Ghost Knifefish is adapted to your local hard water,
and is feeding and growing merrily, it could live a long and happy life,
provided water quality is excellent.>
I read that letting the water age with aeration helps reducing the ph a
<Depends on the water chemistry. Aerating doesn't do anything by itself.
But some water has lots of dissolved CO2, and aerating drives this off,
raising the pH. That's the commonest scenario.>
but It'd be very difficult to do water changes for a 60 gal/150 gal that
way and isn't very practical. I am very confused as how to go about
Out of topic, but is normal clay a good substrate for an aquarium?
<Don't know; never tried it! Lime-free sand is ideal for Black Ghosts,
while gravel works okay if needs be. So long as you aren't too fussy
about the types of plants, putting them into the gravel, and then
inserting fertiliser pellets every month or so, will result in adequate
Sometimes even better! Vallisneria for example couldn't care less.>
i wanted to go with simple plants like Anubias and didn't want to spend
a lot on ADA, unnecessarily.
<If you grow low-light plants like Anubias and Java Fern, avoid
expensive plant-friendly substrates. The Anubias and ferns won't use
them, getting nutrients from the water, but algae will take the
Will a slight murky water during water changes affect the fish in any
<Black Ghosts don't mind a bit of cloudiness.>
Thank you so much again, Neale. Your help is much appreciated.
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:
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
<Please learn to/use WWM; as some 30,000 others do daily... the search
and the files linked above>
And if you can tell me what other fishes I can add to the tank that he
is not going to be stressful, I know they has to be bigger than him or her but I
mean what kinds? Thank you so much for responding and sorry to bother :-)
<.... read where I last referred you. BobF>
Sternarchus albifrons tankmates/comp.
Hi! I just got myself a new tank around a month ago and I am starting to look at
fish to put in it. My number one choice is a black ghost knife fish and I have
many hiding places and a big tank. I have been looking up what tankmates are
best for the BGK but I keep getting a bunch of different answers.
<Need to be peaceful... not too small, tasty, and not too big and aggressive>
I have one site saying tetras and then another site saying to not put in tetras.
I was thinking of maybe some dwarf cichlids, clown loach, Bolivian rams, and
maybe some catfish.
<Mmm; well; not too many or large Loaches or Catfishes... as the BGK spends most
of its time on the bottom... not a great competitor for food>
I cant get any straight answers and I know this is one of the websites I do
trust. I also have some guppies in the tank right now to help build up algae and
things like that and then I am moving the guppies back into their own tank once
i get my knifefish.
<Umm; DO read here:
and the linked files above for background. Bob Fenner>
Apteronotus; tankmates /Neale's input
Hi! I just got myself a new tank around a month ago and I am starting
to look at fish to put in it. My number one choice is a black ghost knife fish
and I have many hiding places and a big tank. I have been looking up what
tankmates are best for the BGK but I keep getting a bunch of different answers.
I have one site saying tetras and then another site saying to not put in tetras.
I was thinking of maybe some dwarf cichlids, clown loach, Bolivian rams, and
maybe some catfish. I cant get any straight answers and I know this is one of
the websites I do trust. I also have some guppies in the tank right now to help
build up algae and things like that and then I am moving the guppies back into
their own tank once i get my knifefish.
<Black Ghost Knifefish inhabit dark areas around waterfalls, rapids and riffles.
They like a decent current, water that isn't too hard, lots of rocks, and some
overhead shade or at least subdued lighting. If you can choose species that
aren't bite-sized that want the same thing, tankmates aren't hard to choose.
From South America, most of the tetras can work (avoid nippy species) with
things like X-Ray Tetras being ideal general purpose tetras that require no
further fuss (they're very hardy and
peaceful). Bolivian Rams would be good too, but will compete for food, eating
the same thing: frozen bloodworms and other tiny invertebrates. So I'd recommend
getting the BGK in and settled, feeding well, and obviously growing before you
add the cichlids. Finally, so far as catfish go, choose species that won't
compete for food. A small Loricariid such as Ancistrus or the smaller Panaque
(like Panaque maccus) would be obvious choices, but Whiptails would be superb
companions too. Corydoras would compete for food, so I'd skip them. Make sense?
Video of BGK 10/29/15
Here's another longer video. Hope it helps, i had to add it to DropBox as its
too big to email
<See this. B>
BGK - hole in side of belly 10/29/15
Firstly I would like to say thank you for all the amazing info on your website
about BGK'S. You are one of very few sites that will help with these fish and I
have learned a lot about what they need from you.
I have had this tank about 15 month now and the BGK'S about 7 month. They are in
a 120lt corner tank with not many other fish. (I know this isn't big enough for
adult size I'm getting a bigger tank at Xmas ��)
I do a 45lt water change/gravel/filter clean every week and a 50% every few
2 BGK's (I think male 4" long & female 6" long)
<May be fighting>
3 guppies (won't be getting more because of BGK'S, had these since
<Am surprised the Knives haven't eaten these livebearers>
1 Pangasius catfish 3" long
<Trouble.... See WWM Re... Remove>
2 marble Pleco (male 5" & baby 2")(Were sold as clowns but their not)
<Mmm; need to know the species; this too could be an issue>
GH 180ppm or 8°d (two different test strips)
KH 60ppm or 6°d (two different test strips
Tank has two airstones and strong filter which I have positioned at the top of
the tank to create a small waterfall/current for the BGK'S. Lighting is 9am till
9pm and its a dim blue spectrum bulb. They have 3 ceramic pots, 3 coconut
shells, two plastic tubes and 2 caves I made from aquarium rocks as well as some
bogwood. No live/plastic plants.
Fed on frozen bloodworm & Pleco/catfish pellets. 2 cubes a day one morning and
one at night after lights out.
Now to the problem...
They both settled in fine and will eat bloodworm from hand and come out in the
day. They get along fine together and seam to play with each other rather than
fight (I may be wrong but it doesn't look nasty)
Yesterday I'd not seen the big female for a while which is unusual because I
watch the tank a lot, more than TV �� she was hiding up behind the filter which
she does sometimes but then I turned the lights out and she came out.
She has a 4mm hole on her left hand side just a bit further onto her belly next
to her gills. Not it's not red or sore it's white ish but pretty deep and I'm
not sure what it could be. Either it's stabbed itself on the bogwood or the
other BGK has nipped it but the other is much smaller or its a water issue. As
no new fish have been added for over a month. The last were the 2nd baby Pleco
Now I know my water is very hard and I spoke to the LFS last week he's ordering
me some peat pad that goes in and softens the water. He said its ok to use with
My question is do you think the GH could be the problem and the hole is due to
<My strong bet is that the hole is due to physical trauma. Most likely
the Pangasiid; but could be the others mentioned>
Apart from the hole and hiding more than usual she is fine and eating/swimming
as normal. She's done a bit of
rubbing on that side but that's it. The other BGK is fine. How would you go
<Move the Catfish... if more damage, separate the Apteronotids>
I don't want to use chemicals unless absolutely necessary but I want to help my
UPDATE - didn't send this straight away as I had no photo to send. I have just
got a short video and you can just see the white 4mm-5mm hole. I did a 45lt
water change/clean again and the BGK seams fine still. The hole seams to be
heeling it's not as open as it was before so I am leaning more to injury than
illness. I will send the video in another email now as it's too
big to add to this (stupid phone)
Thank you in advance for any reply
<DO be a keen observer here.... some one in your system is beating on this fish.
re: BGK - hole in side of belly.... Pangasius incomp....
Thank you for the quick response hun. Will have a look about the catfish now
didn't think there would be an issue with the two together
<Do you have any idea of how large and aggressive that swai cat gets?
but as I'm getting a larger tank soon I'll have space to separate them. I watch
the tank a lot so ill turn the lights off and see how they are in the dark.
Everything seams to leave the BGK'S alone because if they don't they'll get
nipped. Even the big marble Pleco (Colin) unless he's stabbed it with a fin.
What tank mates would you recommend with BGK'S?
<.... this is also archived on WWM>
Obviously bigger fish to avoid bullying. The BGK at 6" is the biggest in the
tank but the 5" marble is stocky.
Someone else said I was lucky they hadn't eaten the 3 guppies, they've had a few
small ones but these 3 keep away somehow. I'll move them to my other tank ��
Black Ghost Knife Fish 9/5/15
Hello! I have a 150 gallon aquarium, and I bought a black ghost knife fish back
in November of last year. It is around 7 inches by now, and hasn't had any
problems with any fish (that I have seen) thus far. However, I noticed today
that the end of the "snout" is gone. It looks like it was chewed off.
It is very fleshy and strands of tissue are floating off from his face. I don't
know who could be doing this. I have a rainbow shark, two algae eaters,
<.... Chinese? As in Gyrinocheilus? These or the shark minnow could be culprits.
Search/READ on WWM re>
some mollies and platies, blind cave fish, a plecostomus, and two smaller
angelfish. I haven't added any fish in a few weeks. Is there anything I can do
to correct this problem?
<Have to separate the Knife, treat it for bacterial/fungus issue. Bob Fenner>
Thank you! Jeremy
Ghost Knife issue... hlth. concern
Hoping you can help.
I have a 28cm ghost knife who is around 5 years old living in
my 250 litre tank with several discus fish and angels and a few cat fish
cleaners. In the recent 3 months my ghosty has shown several like blood
spots on his tail and now has a few more initially I presumed that my
sucker fish were sucking algae off him and therefore creating blood type
blisters but it is getting worse.
Any idea's on what it is and how to treat?
<I concur re your guess that this fish is likely being traumatized. What species
of catfish are present? Does you Ghost have a cave/place of its own? Is this
near where the Discus, Angels hang out? Bob Fenner>
Re: Ghost Knife issue 6/10/15
Yes my Ghost does have many places to hang out and hide as the tank was set up
mainly for him and my discus and the other fishies are 'add ins'.
The cat fish are bristle nose but I am starting to think that it is possibly my
5 loaches doing it as they are the golden sucking loaches.
<Well; may be the loaches, not strange that these should go after an
Apteronotid... is it possible that some element of the decor (sea shell, sharp
rock) has cut into the knife?>
Your help is appreciated.
<Glad to assist. Bob Fenner>
BGK care and compatibility questions
Hi Crew. Thanks for all you do for the hobby.
<A pleasure to aid (educate, inspire) others; as you know>
I've been keeping some fresh and mostly saltwater (only fresh these
days) for 25 years, and I've always wanted a black ghost knife--a
neighbor had a very tame one when I was quite young, and I loved it.
But I never felt I had an appropriate tank for one; I've never had a
large enough freshwater tank before, and never a tank with appropriate
tankmates. Now I think I might. I've read through the FAQ's
on BGK's, and found some answers, but not everything I need to know.
First, because I know everything depends on it, let me tell you about
the tank: it's a 150G (long, not high--I have one of those, too!), using
a Fluval FX5 for primary filtration, assisted by a HOT magnum just for
water polishing and carbon, and 4x96w 6500K power compacts for light.
The tank is pretty heavily planted, mostly several varieties of swords
and Anubias, and some java fern, accented with pieces of driftwood.
Water parameters are 0 ammonia, 0 nitrite, nitrates 15-20, ph is around
6.4, and temp is 80 F. The tank was converted back to fresh water
2 1/2 years ago. I intended it to be a discus tank, but my first
attempt at discus keeping was not successful, and I gave the surviving
discus to someone who could care for them properly. (The discus
weren't eating well--they seemed unable to "catch" the food in the tank.
I'm now given to understand the problem was probably too much current
from the FX5.) The tank's current occupants were mostly selected
with discus' warm, soft water conditions in mind: a large school of
cardinal tetras, a pearl gourami, Bristlenose Plecos (which have been
mating!), 8 Otocinclus cats, and four pairs of blue rams. I also
added three clown loaches about a year ago to take care of a huge snail
problem that came in with the plants. They seem to be doing well,
the largest has grown to about 5", with the other two more like 3".
Most recently, I added 6 angelfish--a consolation for not keeping
Tonight, it occurred to me that the time might be right for a black
ghost, or perhaps two. I know they would eat the tetras when they
get big enough, but the tetras have started to die off, apparently from
old age--their tails get more and more hooked downwards, their colors
begin to dim, and eventually, over the course of weeks, they get thin
and die. At first, I thought it was a disease, but now I don't
think so. They're over two years old, and I think they've just
reached the end of their lifespan. I don't plan to replace
them--at least not with more small tetras. Perhaps some Von Rio's?
<A good choice here... or (for me) Bleeding Hearts, other
So my first question is compatibility. Do you see anything that
would be a real problem?
<Mmm, no. Just care to make sure the Knife is getting food amongst so
many competing fishes, in such a large setting>
I was somewhat concerned about the loaches and the rams, but I've never
seen the loaches act aggressively towards each other or anyone else, and
the rams mostly keep to themselves, really. I thought that with
the high plant density, the BGK would be able to find a nice quiet nook
in which to be happy.
My second question concerns keeping BGK's together. I know that they
get big, and are generally a one-per-tank fish, but a couple of times in
the FAQ's crew members commented that two might be kept together if the
tank was large enough--but no one ever said how large is large enough!
What about a 150? If I started with two 4" BGK's introduced at the
same time, does that stand a reasonable chance of working?
<Two would make for a more interesting, interactive display. I give you
good odds that a couple would learn to get along in this setting>
Thanks in advance for your help.
<Welcome. Bob Fenner>
BGK ninja 2/12/13
Hello my fine fishy family,
I recently wrote to you about stocking my 90 gallon tank around a black
ghost knife fish. While I didn't go by the list precisely I tried to
find a variety of fish that would fit the fast moving, soft water of the
ghost knife. So right now I have one BGK, 10 Banded Rainbowfish
(Melanotaenia trifasciata) (the largest being 4 inches and the smallest
2 1/2 inches) and 12 Longfin zebra danios. I figured to myself in a year
or two the BGK would be able to fit the danios in his mouth but they
would have probably died of old age anyway. I did not count on the BGK
being an eyeball plucker though.
Of course now that I Google those exact words I see its more common than
I thought. Even so if I had know I probably would have gotten them
anyway because they're pretty fast little things anyway. Not fast
enough. Of course they stick their head right into the lions den as it
were. The 2 danios this has happened to, are doing surprisingly well for
being so terribly maimed. My question then is several fold. Do I take
out the 2 danios and put them into the quarantine tank where I currently
have hatchets and Cory cats waiting to go into the display tank?
<I would not move the Danios... their eyes will not regenerate...>
(Qt tank is 20
gallon long) Do I take a few more danios with them so they don't start
to bully the others because they're in a small group?
<You could if you wanted>
Do I take out all the
danios and buy and new tank for them?
<If you'd like them to live a quality life, yes>
Do I take the rainbows out too?
<These are likely fast and smart enough to avoid the Danio's fate>
Should everyone (except for the BGK) go in a brand new 40 gallon (after
cycling) and I just have to find large passive tank mates for the BGK?
<Again, this option is up to you>
Info that you will probably find relevant. The display tank is ammonia 0
Nitrites 0 Nitrates 20. Temp is 75. I feed the BGK blood worms and brine
shrimp. Maybe if I move to superworms he would stop going for the eyes?
really at a loss here. Thank you all for your wisdom and patience!
PS I do fast them all once a week. Could that be part of the issue?
<Not really... the fasting is a good practice. Bob Fenner>
I have a 90 gallon tank with 2 adult angelfish, 4 juvenile
discus, 2 adult parrot cichlids,
<These may turn on the other Cichlids here>
and a very tiny algae eater (just bought).
We have a variety of plants, a large piece of driftwood, and looking for
another shipwreck/pipe/vase type of decoration to add. Would a black
ghost knife fish work in this set-up?
<Mmm, not really... too hard to feed w/ what you already have here>
What types of fish do they/don't they get along with? I tried reading
your compatibility FAQ and found a variety of answers for other species.
I figured I'd ask about my specific set-up. Looking forward to hearing
<Welcome. Bob Fenner>
Stocking a 90 gallon, FW w/ Blk. Ghost
Howdy all! Thank you so much for all the hard work you do by keeping us
informed. I am currently fishless cycling a 90 gallon tank and am trying
to make final decisions about who gets to go on in. The fish
that all others revolve around, the centerpiece if you will, is a black
<I see. Now, remember this species comes from fast-flowing,
well-oxygenated, not-too-warm waters around waterfalls and riffles. So
you want species that enjoy current and don't mind turbulence. BGKs are
easy to keep when small, but become steadily more difficult to maintain
as they age, so what you don't want are fish that will respond badly to
extra powerheads or other sources of water current. Equally important is
the large size of adult BGKs; even if they aren't especially predatory,
they could scare small, nervous fish. Conversely, BGKs are very
sensitive to nippy and aggressive fish, so tankmates should be robust
The others I'm thinking about going with it are 5 Denisoni Barb (Puntius
<An excellent choice. While Puntius denisonii do prefer cool water,
15-25 C, at 24-25 C they'd be good companions for BGKs.>
1 African Butterfly Fish (Pantodon buchholzi),
<A bad choice; comes from still water and dislikes current.>
5 glass catfish (Kryptopterus minor),
<Doesn't like very strong water currents either, but if there's a gentle
area in the tank, it might do okay.>
and here's where the list gets more in the air 5 silver hatchets
1 female golden gourami (Trichogaster trichopterus), 1 female blue
gourami (Trichogaster trichopterus), (Not sure if 1 would be better or
<Gouramis prefer still water, so not a good choice.>
and finally I also really enjoy the Leopard Bushfish (Ctenopoma
I wasn't really considering the gouramis until recently because my
husband and I went to the fish store together and he said he liked the
fish but the tank seemed to be lacking in color. Anyway can you
advise me as to which mix works well? The two I like best are the ghost
knife and the Denisoni.
The water perimeters seem fairly close in range, but I'm worried about
those gouramis and if the butterfly fish will bother the hatchets. Not
to mention I'd rather not overstock the tank in general. If the
gourami isn't a good match what other colorful fish might you recommend?
Thanks so much!
<Do look at fish from the same "flowing stream" environment as
Apteronotus albifrons; for example Corydoras catfish, certain dwarf
cichlids (Nanochromis, Steatocranus), most Barbs and Danios (look at the
bigger species, which can be gorgeous), or Barilius spp "Hillstream
Trout" if you don't keep the tank too warm, even Swordtails though these
do prefer hard water so may not be ideal. If you're up for a challenge,
Geophagine cichlids could work really well, many are quite colourful
(e.g., Satanoperca leucosticta or the excellent Geophagus altifrons)
though they are sensitive to water quality, especially nitrate levels
above 20 mg/l, but then so are BGKs. Cheers, Neale.>
Black ghost knife fish hurt bottom fin and
won't eat... Nutr. and in w/ incomp. tankmates
Hi, I have had my black ghost knife fish for over a year and a half now
in a 60gallon tank with 2 Severums, a jewel,
<Mmm, not really compatible w/ these cichlids... and the Severums
will need this volume plus for themselves>
a Bala shark, a cribnasis, a Pleco, and 3 rainbow fish. My knife
is about 7.5 inches long and eats a variety of frozen and
freeze dried bloodworms.
<See WWM re these sewer fly larvae. Implicated in
She has had a few issues in the past with cuts in her pectoral
<? From what?>
but she has been fine for a while. Recently however she has stopped
eating for over week now, and she isn't hiding in her cave anymore,
instead she's just laying along the side of the tank. her entire
bottom fin is all severed like a feather.
<... see above. Needs to be moved elsewhere, and fed better foods.
See WWM re: http://www.wetwebmedia.com/FWSubWebIndex/bgkfdg.htm
and the linked files above>
The end of her tail is also red and bloody, and she has a Slit on
the top of her. Right before the white in her tail. It seems like this
happened over night.. What do I do?
Thanks, Aubrey Theisen
<... read, act. Bob Fenner>
Black Ghost Knife and Discus, comp.
First I would like to thank you for the wealth of knowledge you have on
It has helped me to avoid several potential disasters with my tank.
I do have a question though that I can't seem to find a definitive
answer for on your site.
I have a 90 gallon planted aquarium with 7 Discus and a BGK about 6
Most of the Discus are juveniles with the largest measuring about
PH 6.8, ammonia 0, Nitrites 0 and nitrates stay around 10 to 20. I do
50% water changes once a week and sometimes do a 20% midweek when I
The temp stays at 83.5. I have a Fluval 406 with foam carbon peat and
bio media, an Eheim 2217 with only foam and biomedia, and an Emperor
400 with active carbon in the refillable cartridges w/ bio wheel (am I
over doing it with the filtration).
Currently the only issue I see is I do not have a quarantine, or
hospital tank due to the fact my wife almost killed me when I got back
into the hobby/obsession of fish keeping again.
All of my fish seem healthy now and the tank has been running for 6
months without issue thanks in part to the knowledge I have gained
about Ghost Knives from your site. From the info I have read on your
site about BGK and there sensitivity to medication, I would like to go
ahead and order and have on hand medication for any outbreaks of
<Just treat w/ raised temperature>
or other parasites and or diseases that may pop up.
I don't plan on adding any additional livestock other than a
snail or two and maybe some ghost shrimp. I have heard about the need
to deworm Discus when feeding them bloodworms
<Limit or eliminate these sewer fly larvae. Troubles
and other frozen high protein foods. Can you tell me what you
would recommend for treating Ick or other parasites and diseases, and
deworming the discus with the BGK also residing in the tank.
<I would not treat in the tank period, and not now anyway. So;
"none of the above">
I find that moving a fish to another tank to medicate it in the past
has caused further stress on the animal and never ended well.
Also what are your thoughts on adding salt to a tank with Discus and
Also your thoughts on BGKs and Discus as tank mates?
Thanks in advance for any light you can shine on this for me.
Jason in Kentucky
<Welcome, Bob in Ca.>
my fish 9/5.5/11
Well I have 2 Dinosaur bichirs, 2 gourmi's, a Pleco, a red tailed
shark, 2 Bala sharks,
<Will get much larger...>
and a Africa brown knifefish. I have a 55 gallon tank with plenty of
hiding holes. Will a black ghost knife be compatible?
<No; issues w/ your other Knife, feeding competition... Read
Also how do I introduce hand feeding to my Bichirs and Knife fish?
<Use the search tool at the bottom left corner of any page... add
the term "freshwater" to your string. Bob Fenner>
Please send me the answers to my email which is... <Done!>
Thank you so much
Black Ghost Knife and Oscar
This morning I was conducting my daily headcount in my aquarium and was
missing my Ghost Knife. Apparently at some point during the night he
jumped out of the aquarium and I found him on the floor.
<Happens. Turns out there are very few fishes, mobile aquatic
organisms that can leave via the top>
He's never been prone to jumping and the lid was shut all night.
The only thing I can think of is that he jumped out the back opening
but that's a pretty tight fit. He was about 10-12 inches long and
would have had to have been trying really hard to get out of that
crack. Also, I recently moved and with the new stand, did not have
enough air hose to hook up the pump. I have a Marineland canister
filter rated for 100 gallons and 2 other powerheads in the tank. Am I
wrong in thinking that these elements alone, without the air pump would
cause enough surface disruption to provide oxygen to these fish?
<Mmm, should... DO can be measured...>
The Oscar is now approx 8-10 inches long now and the Plec about 5.
<I would not keep an Oscar and Apteronotid in the same
Also with these fish still in the tank is there anything you would
recommend adding in there?
<Please read here: http://wetwebmedia.com/FWSubWebIndex/oscarcompfaqs.htm
I would like to keep another Black Ghost Knife but if I got a small one
I don't see him doing well in that environment.
<Agreed. The Oscar is too likely to damage the BGK, eat all
I was also thinking of setting up a different tank and putting a BGK
and a Xenomystus Nigri in it with some live plants. Does this sound
like a good system as far as water conditions and behavior?
<Mmm, maybe... a bit boring for me... I'd add some fish with
movement, colour... Perhaps some Melanotaeniids/Rainbows>
Thank you for your time,
<Welcome. Bob Fenner>
Can a community tank include Black Ghost Knife & Clown
Today sadly I had to euthanise my large Oranda Wolfgang, I'd had
him since he was a tiny baby, I'm not sure what happened to him,
his Wen grew so big it covered his eyes but he was still happy, he was
always a little top-heavy
A couple of months ago he just started lying on his side & not
moving much, I thought (seeing all the water parameters were fine) that
it was just because he couldn't see & was unsure of what to do,
he'd still right himself to eat & swim around the bottom. The
past week he's been really bad, barely moving except for dinner
& he was starting to get thin & get pressure sores on his sides
from lying down, so sadly, the time came, he's now buried under the
hibiscus with Yolky his longtime Ranchu friend
What I was wondering now was, I have a 4' x 2' x 2' tank
that's just got a peppermint Bristlenose in it & so I was
wondering what to put in the tank.
When I first got into fish keeping about 25 years ago my Mum bought me
a Black Ghost Knife fish, he was only tiny when she got him & over
the 8 years that I had him, he grew to over a foot in length. Poor Moo
though taught me the valuable lesson of having a back-up heater in the
tank as one day in winter he started fitting & it turned out that
the tank was cold as the heater had blown up. It was such a loss to
We then went onto the community type tank with clown loaches, Corys,
glass cats, various large tetras & a butterfly fish.
I do like the clown loaches, they've got a lot of personality &
I would dearly love to have another black ghost knife. Would they
<Mmm, can, yes>
I was thinking 1 black ghost knife & maybe 6 clown loaches, maybe
some sort of Corys, the glass cats & what about Congo tetras?
<These two would add colour, motion to the mid-water area>
I know that I can't have small fish in with the ghost knife (Moo
ate Mum's beautiful guppies when they had to move into his tank for
awhile) & I vaguely remember that you can't have Plecos with
knife fish but would those others mentioned be ok?
<Yes. Do see/read on WWM re the water quality, nutritional needs of
all you list here>
Also, what about salt in the water?
<Not a good idea generally. Read here:
I always used to put some conditioning salts in with Wolfgang &
Yolky, it was a mix of pool salt, Epsom salts, bicarb & Melafix as
well as Prime & Stability.
<Shortened their life times>
It's been awhile since I've had tropical fish as after I lost
Moo I went into marine fish for about a decade but then swapped to the
Orandas 'cause I thought that they would be easier to look after
(give me back my marine tanks any day!)
Sorry about the long winded waffle but I really wasn't sure & I
would like to start off on the right foot again.
Also, in terms of cleaning the tank out, it's warm anyway as
Wolfgang liked it a little warmer, should I do a full water change or
just a % & clean out the filter? It should be good bacteria wise as
it's been running for years.
<I would change out most all, vacuuming the gravel>
Thanks in advance for any advice & thanks also for reading.
<And you, Bob Fenner>
BGK tankmates, not turtles 4/16/11
Hello WWM Team!!
Hank here, I am a longtime herp-hobbyist and, I recently discovered the
world of aquaria! Let me begin by saying your site is definitely one of
the top three sites (regarding usefulness of both Herps, and Ichs) I
have scoured, so far. your BGK area has answered most of my questions
I recently added (4/14/11) a BGK, "Little Ninja," to my 28g
bow-front tank that has been in use a little less than a month. Before
Little Ninja was added the inhabitants included a hatchling YBS (c. 1
month old at most, c. 2" nose to tail-tip "Phinn"),
<Mmm, not compatible>
a Pleco (specific species unknown, as I am weary of trusting LFS in
I.D.ing them properly, c. 1 1/2-2", ), and a female Golden Gourami
(c. 2 1/2-3", "Wanda"). These will be the ONLY
inhabitants besides two or three emerald Corydoras. Thanks to you guys
I am well aware of the *possible *size of the BGK and, hopefully, he
will get as large as possible.
<Not here, no. This volume is too small... and the shape... would be
better to be long, flat>
I do not want his growth stunting so in August I will be upgrading to a
much larger tank size (at least 75g and will be the only inhabitant
besides the Corydoras and another Pleco [hopefully an albino Sailfin
<Oh! I'd add some other "more open behavior" life
My question is are these tankmates SAFE for my lil' Ninja until his
upgrade, regarding both bio-load and the Gourami ( two reptile
<Not really, no>
And, is the dechlorinator I use for the turtle safe for him (it
doesn't have copper in the ingredients, but I'm not sure about
the other ingredients, it's also supposed to promote healthy slime
coat for amphibians)?
<Is likely fine>
He currently lives in a ship aerator in my sand-bottom tank, next-door
to Wanda who has taken up in the hollow root system from my LFS.
He has been very active, as active as any healthy fish should and, he
immediately began going in and out of his ship within hours of
introduction, and began investigating the tank, and eating(with the
light on!!). Wanda doesn't hog food, they share blood worms, and
Wanda has been very nice so far, she has a history of non-violence
unless forced (she use to be in another tank exactly like the
aforementioned[reg. size] with a Pleco[1 1/2-2"], male golden
Gourami "Napoleon" 2-3", six bream fry( I caught and
added these as feeder for the Eastern Painted Turtle
"Rembrandt" or, "Remi" c. 5 mo. c. 6"
nose-tail [four have disappeared!]) and Napoleon bullied her to the
point they literally "locked jaws" until I lightly touched
Wanda, and they separated. I IMMEDIATELY separated them realizing there
was probably too much fish for that tank. Once separated I temporarily
housed Wanda with a 2yo male YBS who also paid her no attention,
obviously(although she would pick the algae off of him(I caught him in
the wild last week sometime), as well as using him for a blind! Now, I
can hand feed both Wanda and Napoleon flake food! And I cant wait till
Lil' Ninja does the same!
Phinn is still a little skittish but has gotten to the point I am
familiar to him. He isn't enticed by any of the fish considering
they are all bigger than him, except for the Pleco, and doesn't
chase any either. I feed both turtles in separate feeder tanks(with the
exception of the four missing bream fry from Remi's tank), and
usually leave them there for at least an hour so they can defecate in
there rather than their aquariums to reduce detritus, and water fouling
a.m.a.p., ideally to reduce clean-up a.m.a.p.
Any advice, suggestions, or questions are greatly appreciated and I
can't wait to hear back from you guys!
<I'd separate this little turtle... place it elsewhere>
Thank you so much for what you guys do,
<And welcome to the wonderful world of aquariums! Bob
Re: BGK tankmates - 4/16/2011
>> Hello again team WWM! And, thank you, Bob!
I apologize. I accidentally sent that email before typing the rest!
Would a 55g long be good for Lil' Ninja until August? And, what
tankmates do you guys suggest? The hatchling turt will remain in the
28g bow-front until august for sure, depending on his size at that time
I will see about a tank upgrade...
Again, I apologize! The same thing happened again!
Anyway, this morning I removed Remi(the 6" nose-tail E. painted)
from his current tank because I
caught him, for the first time EVER in the months I've had him,
chasing and nipping the Plec in there (Gggrrrrrr, I was mad but, I
should have known better!!).The Plec is fast enough to escape Remi but,
Remi sneaked up on him. So, in the 28g bow-front formerly housing Remi,
Napoleon(juvenile male golden Gourami, and the Plec it is just the Plec
and Napoleon, lightly planted in the corners with fake plants( I am in
no way ready for real plants yet!). Do you have any tankmate
suggestions for this one as well?
<Do read here please: http://wetwebmedia.com/FWSubWebIndex/bgkcomp.htm
and the linked FAQs file above re Stocking/Selection, and the same for
the other species you're housing here... On WWM. The search tool is
likely your best route/tool here>
Re: BGK tankmates - 4/16/2011
My BGK is still acting healthy and eating his blood worms and
However, I noticed earlier today he has a white spot on his underside
about where his fins and gills connect.
<May be this fish's anus...>
From what I've both seen and read, so far, the stripes on his head
and tail are the only markings(if it turns out this is just another
color mark I'm delighted!! Otherwise...) Is this a normal color
mark or, the beginning of something like Ich or, another
parasitic/bacterial infection? I am about to move him into his own 30
gallon temporary Tupperware bc I failed to quarantine him before
introducing him to his current tank(sorry :-/ ).
<I would not do this. Quarantine is too late>
Re: BGK tankmates - 4/16/2011
Thank you, luckily I was going to cycle the Qtank for several hours
before adding BGK and still hadn't added him when I received your
response. The whit spot on the bottom IS the anus. But, just in case I
will continue to keep an eye on him!!
As always thanks for your passion and information!
<Always welcome. BobF>
Siamensis and Black Ghost Knife Fish, incomp.
I have a 60 gallon tank with 4 Siamensis (3 inches), an Angel, Pleco, a
few Rasboras and Rummies, and a 14 inch Black Ghost Knife Fish that
I've raised from 3 inches.
I've had the Black Ghost about 5 years; the Siamensis I got about a
Everyone seemed to be getting along fine until the other day I noticed
the Black Ghost had a wound at the underside of the base of his tail.
At first I thought he might have caught it on some driftwood, but later
I noticed that the flesh was actually gone down to the fine bones in
his fin. Then today, I caught my Siamensis nibbling on him at the wound
site. In fact, they would not leave him alone, even though he kept
trying to get away. I isolated him immediately, but my question is, do
you think the Siamensis might have caused the wound in the first place,
or were they merely taking advantage of the opportunity for fresh
<Can't say, but I know of other cases of SAEs doing such
From everything I've read, they are not aggressive towards other
fish in a community tank. I've double-checked to make sure they are
indeed true Siamese Algae Eaters, and not one of the false variety,
which, I understand, can be aggressive. They are definitely the true
Crossocheilus siamensis, so I'm puzzled.
I'm definitely keeping Squiggles (the Black Ghost) in quarantine
until he is healed, but I'm concerned about putting him back in the
tank with the Siamensis, especially now that they've had a taste.
<I would be (unfortunately) separating these fishes. Bob
Black ghost knife fish, incomp. 10/23/10
I have 2 BGK fish in a 50gal tank
<Mmm, I would not put two of these Apteronotids in such a
along with 3 clown loaches. There are 2 PVC pipes that each of the BGK
fish hide in and another cave that the clowns play around in.
The water conditions are normal.
<You should read re the range of "normal" cond.s for both
I clean the tank with a 60% water change about once a month and do
20%-30% water changes along with cleaning the filter every 2 weeks.
I usually add a stress coat or something similar to the tank after a
large water change. Of late I have noticed the BGK fish have rips in
the anal fin. what could be the reason??
<Fighting amongst the two>
The tank is around 6 yrs old now and the bigger BGK has been there
since the beginning.
<I'd trade out, sell/give away the other one; stat.>
Black Ghost Knife and Oscar tankmates. Holy incomp.
I have a 55 gallon tank with a 3" Albino Tiger Oscar, a 5"
Black Ghost Knife and a 3" common Pleco.
I would like to get some other fish to keep with them. I would like to
know what types of fish my tank would accommodate with respect to a)
bioload, and b) temperament.
<Nope. Even by itself, the Plec is going to put a really heavy load
on the aquarium. Add an Oscar, and things get dirty pretty fast. An
adult Black Ghost as well? No way.>
I was thinking maybe even an Electric Blue Jack Dempsey because I read
that the Electric Blue was a genetic defect that generally made for a
less aggressive and smaller variety than the standard Dempsey.
<Heard rumours about its lesser aggression too, but frankly, this is
still a crashingly bad choice for this tank. Central American cichlids
have very specific requirements, and mix poorly with South American
I wanted to confirm that assumption before I bought one. My Oscar is a
very passive fish, however, I do understand that they get more
territorial as they mature. Would the EBJD be a suitable tankmate?
<No, it wouldn't.>
This would really be my preferred option as I like the more sturdy,
larger fish. Is there a breed of cichlids that I could maybe put
another 3-4 fish in this tank peacefully? I know you may not like it
for it's size, but I will be upgrading to a large canister filter
soon and would really like to have a few, more interesting fish.
<I think you need to review the needs of the fish you have. An adult
Black Ghost is upwards of 50 cm/20 inches in length, and extremely
sensitive to poor water quality. Most folks fail to keep them alive for
more than a couple of years. When was the last time you saw a full
As for dither fish; what would you recommend? I've read where you
have advised Clown Loaches and Angel fish, but I would like something a
little more exotic. Silver Dollars are okay but I've read that they
can be a little nippy. Could a few Bala Sharks or Serpae Tetras
cohabitate with the fish I already have?
<Serpae tetras are FAR too nippy to mix with any of these
Are there any freshwater puffer fish that would survive with these
<Repeat after me: puffers aren't community fish, puffers
aren't community fish. By all means keep a puffer, but in its own
tank. South American puffers and Carinotetraodon irrubesco are the two
species that might be considered, being relatively peaceful. But SAPs
are too nippy to keep with Oscars, and adult Oscars would simply view
them as a potentially edible nuisance. As for Carinotetraodon
irrubesco, this species would also be Oscar food, even though it
isn't especially nippy.>
Thanks in advance for the help. It's very much appreciated.
African Butterfly fish Compatibility 1/25/2009
First of all, thank you for the superb information you have on your
I have a well established 125 gallon (US) tank with an average Ph (I
haven't tested it in a while, but everyone seems to tolerate it),
housing 6 small silver dollars, a 4 inch Black ghost Knife, a 2 inch
Leopard Ctenopoma, an 8-9 Rhino Pleco, two Botia Kubotai, and two Kuhli
loaches (I would move them to a tank where they were less bite sized,
but catching them in my well planted tank full of driftwood is near
impossible). They usually all stay near the bottom and middle of the
Recently, while browsing my local fish store, I noticed that they had
an African butterfly fish in one of their tanks. I'm wondering if
the Butterfly fish would be suitable for my tank.
<Possibly, but Silver Dollars may harass it. Pantodon buchholzi is
also somewhat fussy about its habitat. It prefers shady tanks and will
normally hang about at the surface where the flow of water is minimal.
Tall or floating plants are a must.>
I feed the tank flake, shrimp pellets and "bottom feeder
wafers" in the day, and at night they get a very small bit of
flake and frozen bloodworms (I plan to get live brine shrimp for the
Knife when my LFS has them in-stock). I have some floating plants that
provide shade (and some security for the Ctenopoma) that cover about
1/4 of the surface of my tank.
My tank lid is glass and relatively heavy, so jumping should not be a
problem. Plus, if I get the Butterfly fish, should I get them in a
<They are mutually territorial and so far as I know, don't form
stable pairs. Allow about a square foot of space per specimen, assuming
each square food has one suitable resting place.>
Re: African Butterfly fish Compatibility
First of all, thank you for your quick response. I don't think the
silver dollars are a problem for the Butterfly fish, since they tend to
be a bit timid, swimming in and out of the driftwood and low plants,
and as far as I know, haven't harassed anyone.
As I said in my last message, I have a large mass of floating plants at
the top of my tank, which should be perfect for Pantodon buchholzi.
The water in my tank is relatively slow-moving, with the water near the
sides a bit faster due to the filters.
<See, you need to be careful here: Apteronotus albifrons will not
live long in a tank with limited water current. These fish come from
rapids and such like habitats, and as they grow, their oxygen demands
go up. (Remember,
when a fish doubles in length, its mass increases 8-fold, so its oxygen
demand gets very much greater than you might imagine.)>
And, my silver dollars are only about 1-2 inches in diameter, do you
think that the butterfly fish could fit it's mouth around them?
also, Do you think it would require anything else than frozen
bloodworms daily and store bought crickets once or twice a week?
<Juvenile Pantodon are best fed on wingless Drosophila, easily
obtained from reptile pet stores. Crickets can be a bit big for them.
In any event, quarantine them first, and during that time, train them
to take carnivore flake and pellets. Once they're on a staple of
that sort, you're better assured good health.>
Re: African Butterfly fish Compatibility... and BGKs -
Regarding the ghost knife and sufficient oxygen, I could add a bubbler
in the tank, near (or in, if that would be better) the piece of
driftwood the Knife fish resides in. Do you think adding a bubbler
could supply the knife
with sufficient oxygen,
<Wouldn't be my first plan of attack. Apteronotus needs crystal
clear, highly oxygenated water. Think of water splashing around rapids
or a small waterfall. That's the goal here. Keep reminding yourself
that most folks kill their specimens within a year or two of purchase,
and you rarely ever see 15-year old specimens a full 60 cm (over 2
feet) in length. Why? Because what works for standard community fish
doesn't work for Apteronotus albifrons. These are difficult fish
for advanced fishkeepers.>
while at the same time not disturb the Butterfly fish? I'm pretty
sure the tank is long enough so that the bubbler can be going on one
end, and the other side to remain mostly undisturbed. Oh, and one final
question: My Black ghost knife likes to "Play dead" during
the day, and then instantaneously start moving again when the light is
turned off. I assume this is normal behavior, being a highly nocturnal
<Yes; indeed, they seem to like to rest on their sides.>
Thanks again! -Jack
Knife fishes... Xenomystus and BGK comp.
It's been a long time since I've had a question for you.
Everything has been going very well.
I now have a 240 gallon tank with a 6" diameter rectic sting ray,
12 inch silver Arowana, 6" Bala shark, 5 ea. 2" clown
loaches, a 5" African knife, and a 5" black ghost knife. I
read somewhere that it was not a good idea to
keep the two knife fish together. I'd like to hear your
opinion/experience on the subject.
<These two Knifefish are very different in terms of habits, so
should cohabit reasonably well, providing each had space and a suitable
Apteronotus albifrons is an electric species, and yes, in captivity
small groups are prone to bullying. This is common to electric fish, in
part because they "jam" each other when confined in small
spaces. Apteronotus albifrons may be kept singly, or else in large
groups of six or more specimens. Xenomystus nigri is not an electric
species (though it may well detect electrical fields generated by its
prey). Although territorial, it is not nearly so aggressive as its
Asian cousins in the genera Chitala and Notopterus. Those Asian
knifefish really do need to be kept singly once sexually mature, the
males in particular being notoriously defensive in the wild, supposedly
biting at humans who wade too close to them! By contrast, Xenomystus
nigri is comparatively easy going, juveniles at least being gregarious,
adults territorial but not much given to tantrums if allowed space to
themselves. Hope this helps. Cheers, Neale.>
Re: knife fishes 1/25/2009
<Most welcome. Neale.>
The mystery of disappearing fry
Hi guys and gals,
You did a great job helping me deal with finicky guppies that used to
drop dead on me for no apparent reason. Now Im back with another
puzzle. Here is the setup: a 38G community tank thats been running for
a while, complete with all necessary gadgets. The gang consists of 5
guppies, 7 mollies, 5 platys, 3 pre-adolescent clown loaches, one
red-tail baby shark Seeking, and a 5 black ghost knife dont ask why,
the oddball was inherited.
<This fish will of course eat baby fish, given the chance.>
I used to have a smaller tank (had to get rid of it after continuous
complaints from my co-habitants) with a mesh breeder in it and this is
where all of the fry from the community tank parents was hanging
<Do bear in mind breeding traps are somewhat less useful than you
might imagine. It's often best to keep livebearers in single
species tanks filled with floating plants; usually, a surprisingly good
portion of the fry survive under such conditions. Traps and nets can
work, but fry will jump out, and some fish will chew through the net at
night (catfish and loaches especially) producing small holes through
which fry can escape.>
Since the smaller tank became no more, the breeder was moved into my
38G and attached to the wall. One fine morning I woke up to find that
all of the fry except two were missing. After a few vocal displays of
frustration and disbelief I went on to examine the breeder which turned
out to be structurally intact.
<Do remove the net, if it is a net-type trap, and review
I pondered what could have happened for a while before falling asleep
and woke up this morning to discover that one of the two survivors a
lovely Dalmatian Lyretail molly fry was gone. Now all I have in there
is a 4 week old guppy.
Needless to say, Im bothered by what have happened. The fry could not
have escaped on its own.
<But they can jump.>
Its also unlikely that they were caught through the mesh walls of the
breeder as those are rather stiff and the mesh is fine.
<Check for holes.>
The only possible answer is that some deviant fish jumped from the main
tank into the breeder, helped itself to baby fish AND jumped back out
into the main tank.
<Possible, though I admit unlikely.>
This is rather advanced thinking for aquarium fish, isnt it? And who is
to blame? Im leaving the ghost out the thing cant decide on whether it
can swim, let alone jumpwho else? Clown loaches?
<Can chew nets.>
They always hang out in the corner together scheming something and
looking suspiciously super cuteAnyone has experienced this before?
<Yes; lost various fry when an Ancistrus catfish decided to graze
algae from the net. I now don't bother with traps much, and instead
use 8 gallon tanks with heaters and simple filters to rear fry, or else
leave them with parents and tonnes of Indian Fern.>
<Better luck with the next batch! Neale.>
New Black ghost knife, comp., sys.
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
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
Everyone is doing quite well, and the Ctenopoma has staked out a
<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
<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
<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.>
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
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
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
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
<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
driftwood that my loaches, knife fish and Kuhli loach were currently
<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
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
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
Black ghost knife fish and tankmates 08/26/09
hi i recently inherited some tank mates i was not expecting
the stocking is a jack Dempsey, flag cichlid, 2 yo yo loaches a black
ghost knife fish, 2x keyholes a royal Gourami and 3 silver dollars
<Hmm... a bit of a mixture there.>
they are in a 200l tank with excellent filtration 2x Fluval u4s and a
Rena xp2 external
<Well, a 200 litre tank isn't really big enough for all these
fish. Now, let's step through them one by one. The Jack Dempsey is
an aggressive, territorial species that could easily claim this entire
tank as its personal domain. While compatible with other Central
American cichlids, this would usually require a somewhat larger tank,
and in any case, the Central American cichlids would all be pretty
boisterous and of course
requiring the same hard, alkaline water. The Flag Cichlid is, I assume,
Mesonauta festivus, a lovely big (20 cm/8 inches) cichlid from South
America. It's a lot like an Angelfish in terms of behaviour, and
mixes with them pretty well. On the other hand, it isn't aggressive
enough to get along well with Central American cichlids, though I guess
a female Jack Dempsey might be less aggressive than a male, so your
mileage might vary on that count. Still, not a textbook combination.
Your loaches (Botia almorhae) would work well with Mesonauta festivus,
and given space, so should your Keyhole Cichlids, Gouramis, and Silver
Dollars. The Black Ghost Knifefish will eventually need a bigger tank,
though a juvenile can work
well in tanks this size. Adults get to as much as 40 cm in length,
though this may take over a decade. The flip side to Black Ghost
Knifefish is that they're inhabitants of fast flowing, well
oxygenated water, and this isn't
necessarily what things like Flag Cichlids and Gouramis enjoy. Still,
provided the turnover is somewhere between 6-8 times the volume of the
tank in turnover per hour, you should be okay.>
my question is will there be any problems i should be aware of?
<The Jack Dempsey is the short-term danger, being potentially
aggressive enough to damage some of these fish, perhaps all of them.
Longer term, you have too many big fish, and even if you got rid of the
Jack Dempsey, you'd still need a tank 50-100% larger than the one
you have now. Once your bigger fish species are above the 15-20 cm/6-8
inch mark, think about either rehoming some of your fish, or else
buying a bigger tank.>
what should i be monitoring?
<Short term, look for signs of fin damage and so on. Make sure all
the fish are swimming happily, and not obviously hiding or cowering in
Longer term, monitor nitrite and nitrate to see that filtration and
aquarium size are adequate to the fish being kept, and if nitrate
consistently stays above 20 mg/l, there's a good chance your
cichlids will be prone to Hexamita infections. Overstocked tanks suffer
acute nitrate problems, even if filtration is able to deal with the
ammonia and nitrite.>
the cichlids were the ones i inherited! thanks in advance Eryn!
<Eryn, please do use some capital letters if you write back. We
really do appreciate them! Cheers, Neale.>
Re: black ghost knife fish and tankmates 8/27/09
Thank you for all the info I have found it very useful. I do intend on
getting another tank soon so I will spread the larger fish out! Thank
you again! Note the use of capital letters! Lol!
<Glad to have helped, and thanks for using capital letters. It
doesn't sound like much to you perhaps, but to other site visitors,
particularly those with reading/learning difficulties, or for whom
English isn't their first language, niceties such as capital
letters, correct spellings, and proper use of punctuation marks make a
huge difference. Cheers, Neale.>
Re: Tiger Barb is getting S shape body! & BGK comp.,
Thank you for your response. I've never heard of whirling disease,
I looked it up & read some interesting info. My barb did eat well
still this morning and does swim OK. At least not in circles YET, like
what it said in the search for whirling. I will isolate him and see
what happens for a few days and if he gets worse I will put him down if
it has to come to that. Thank you much!
I do have another question if you don't mind. I have been
researching info on keeping Black Ghost Knife fish. What an awesome
creature! Before I do buy one I'd like to know if he would be OK in
one of my tanks. I have 2 setups that are possibilities..
1- my 90 gal, setup about 3 years. Water chem..nitrate O.. nitrite O..
ammonia O..pH 7.6 Fish in tank- 3 blood parrots 1 Jack Dempsey (oldest
fish in tank and as sweet as can be) 1 Raphael cat, mom Kenyi and her 2
babies, (took dad out of tank picking on fish) 2 rainbow sharks, 1
jewel, 1 Severum, 1 l Lg Danio.
<Mmm, not a good setting... the Cichlids are too likely to work the
2- my 55 gal setup about 2 years. Water same as above. Fish in tank - 5
Australian rainbows, 2 diamond tetra, 2 rosy barbs, 2 gold barbs,2
black skirt tetras, 2 clown loaches, 2 queen loaches, 2 Chinese algae
eaters 6 coolie loaches ,This one I'm a bit concerned about the
coolies to be eaten (looks like worms) unless I house them else
<Mmm, not by the BGK, but the larger loaches might well bother an
Apteronotid too much here as well>
I do have a total of 9 fish tanks setup.
I do weekly water changes 40-50 %
<Mmm... I would limit this to about 25%... unless you're
storing, checking the make-up/exchange water, it's too easy to get
into trouble with source water quality variability>
& both these tanks run on Aqua clear 110 filtration. Also have
extra filtration systems available if I do need to add one more. Thanks
I would appreciate knowing what you think before I buy this fish. I do
have a 29
bow front but not setup yet.
<I would eschew the stocking of a S. American Knifefish in these
Re: Tiger Barb is getting S shape body!
Thank you, I'd rather know now then be sorry later!
<Ahh, yes... understood, and agreed! B>
Black Ghost Knife Q,
comp. with loaches 4/8/09
First I want to say that I've read all the questions and responses
on your BGK page. I'm in the process of setting up a 55-gallon
tank, and once it is completely cycled I plan on waiting a few extra
months to be sure
everything is where it should be as far as parameters and all go.
Currently I have 2 tanks set up, a 30 and a 20 gallon, both heavily
planted, that I've had for nearly 2 years now. I have 3 yo-yo
loaches (2in long each),
and a starry night Pleco (about 2 1/2in long) in the 30, that I plan on
transferring to the 55 once it's cycled and ready to go. I've
read that the Pleco will only get to be 4in and the loaches no one
seems sure of. I've
read variously that they will be anywhere from 4 to 8 inches long once
<Mmm, Botia almorhae grows to about a maximum of 13 cm./4 inches in
the wild... yours will likely get no larger than 3" over time in
But my question is will they (the loaches and the Pleco) be good tank
mates for the BGK? The loaches currently school and sleep with a pair
of Cory cats, and don't bother anyone (I have 5 Danios in that tank
as well and nothing else) but wasn't sure if that would change once
I get them in with the knife.
<Mmm, likely so... though the loaches may be a bit more active than
the Apteronotid would prefer>
One other question if I may. I originally got the yoyo's to help
with a snail problem, but they are totally ignoring the snails.
I've had them almost 3 weeks now and there are snails small enough
for them to eat. The
only things they are interested in eating are sinking algae wafers.
I've tried shrimp pellets, frozen shrimp and bloodworms, regular
flake foods, freeze-dried shrimp and bloodworms, and daphnia, but all
they do is shake the food around till it falls apart, or take a bite
and spit it out, and then leave. The algae wafers they really chow down
on however. I'm happy they're eating and acting normally, but I
wasn't sure if they'd get the nutrition they needed from only
the algae wafers. Thank you for your time and any help you can give
<You might want to try "smooshing" a few of the snails
(with your fingers)... to help your loaches develop an awareness
("taste") for the snails. Bob Fenner>
knife attacked by loaches 1/14/08 We purchased a black ghost
knife 3days ago and from the very beginning the fish swam near the
surface on it's side and it seldom ventured to other parts of the
tank. The fish was approximately 4cm in length. In our tank we also
have 2 clown loaches, 2 Pakistanian loaches, 1 Corydoras, 1 angelfish,
3 gouramis and a small eel. <One Corydoras isn't nice. Corydoras
are SCHOOLING fish, which means they should be kept in groups. Please
add some more of the same species (unless you want to accrue a lot of
bad Karma from the catfish gods).> We started noticing that the
black ghost knife was being attacked by the loaches. The clown loaches
are approx 6cm and Pakistanian loaches 4cm. The tank is 4feet in length
(980 Aqua One) The tank has 2 plants and water is changed regularly,
25% biweekly. There is a large rock with many holes to swim through and
places to hide as well as a fake pot with hiding capability. The temp
of the tank is approx 28degrees C. The tank was 34degrees C when the
fish was first put in; our thermometer was not working but I realised
the temp when I stuck my hand in. I slowly reduced the temperature
using ice blocks. The pH of the tank is approx 7.2 The bottom feeders
are fed the appropriate pellets once a day and we were feeding the
others blood worms. The only other thing I have noticed in the tank is
a yellow (algae?) growing on the sides of the tanks in round circles
similar to what would be seen with bacterial growth. We put in
anti-algae drops and cleaned the tank to deal with this. I have not yet
observed any re-growth. <Don't use Anti-Algae medications; they
cause major problems, not least of all their toxicity to other
organisms as well as producing nitrate spikes as all the algae die.
What you have sounds like Diatoms, a type of algae that grows most
noticeably in aquaria that are not adequately illuminated. Easily
beaten by installing strong lights and lots of fast-growing plants.
Nothing else works, other than manual scraping.> 1. do you think the
ghost knife was unhealthy from the beginning judging from it's
behaviour? <It was probably fine. But Apteronotus albifrons is NOT
an easy fish, and is extremely sensitive to poor water quality as well
as medications/potions of various types.> 2. is it normal for
loaches to attack black ghost knives? <Loaches are, with a few
exceptions, NOT NICE FISH. They aren't community fish (exceptions
are Kuhli loaches, Weather loaches, and to a certain degree Clown
loaches; everything else is more or less aggressive and should be
treated as such).> 3. We would love to get another black ghost knife
but not if it is doomed to die before it's time, can you suggest
any other reasons for the loss of our fish and tips to keep one safe in
future? <Hmm... not impossible to keep, and under good conditions
live many (10+) years in captivity. But you do need to cover all the
bases... these aren't like Danios you can just add to a tank and
hope for the best. They have very specific needs in terms of food,
hiding places, substrate, etc. Do read here:
http://www.wetwebmedia.com/FWSubWebIndex/bgksys.htm If you need more
info, get back in touch!> Thank you for your time. Sincerely, Ali.
<We're happy to help. Good luck, Neale.>
Knife Fan Challenge, comp. 12/19/07
you for your help in setting up our tanks (5, 48 and 75 gallons.) Due
to Mr. Fenner's enthusiasm, I am now a Knife fish fan. I am now
wanting to set up our final and largest, but before I did that, I
wanted to double-check that I'm not headed for disaster. And as a
side comment, it is frustrating with so much information on the web
there are often conflicting opinions. For example, I thought my African
Brown Knives (not Asian) would not be compatible in a pair, but after 6
months they co-existed peacefully, alongside one Black Ghost Knife who
is now the same size as them at 8 inches! After finding a photo on the
internet of a man holding a baby Black Ghost Knife in his hand that was
born in his tank, I want to see if my Knives will breed as well, or at
least, co-exist peacefully. I know this is an unusual undertaking, that
is why I wanted to check with you, the supreme experts, first. If I
were to get a tank of 125 gallons, then 3 African Brown Knives (24
inches of fish) with 3 Black Ghost Knives (45 inches total) would be 69
inches of fish (using the old rubric of one inch per gallon.) I also
have had one Bala with the knives who has been happy and health and is
now 9 inches (will get 12 I read.) I have also had 2 rubber-nose dwarf
Plecos, 2 pictus Pim catfish and a Featherfin catfish, apple mystery
snails and a three-striped Corydoras. Will or can these peacefully
co-exist as the ghost knife fish become larger? <In this size
system, likely so> So far all have been fine on a blood worm diet,
weekly 50% water changes and vacuuming and testing the water weekly.
The three knife fish have done well, but after I add the three more,
and as the Black Knife fish grow larger, can I expect them (or the
Bala) to eat the dwarf Plecos, pictus, the Corydoras or the snails?
<No. They should be fine together> Then, if I may also ask, for
the 75 gallons now that the tank is ready with perfect water
conditions, do you approve of our adoption plan: Glass Fish,
three-striped Corydoras, Round Glass Fish, Clown Plecos (4 inch
dwarves), rubber-mouthed dwarf Plecos, one male Beta, guppies, silver
hatchetfish (2.5 inches) or marble hatchetfish (1.5 inches) and either
a Featherfin catfish or Bugeye Synodontis catfish. How does it sound?
<This mix for your 75 should work... I would go with the smaller
Synodontis species. Bob Fenner>
Black Ghost Knife fish pairs? 8/13/07 I just discovered
your website, and it is wonderful!! I've found so much info on
BGKs! It has been very helpful. <Ah, good> I do have a quick
question. My husband and I bought a BGK about a month ago (Oscar), and
he's been doing great! I had read in a fish forum about getting
more than one. Several people claimed they had a pair, and they got
along great and seemed to enjoy having another "friend" like
them around. <Mmm, the exception actually... most Apteronotids fight
in small confines> So, today we bought another BGK (Fritz). Though
Oscar hasn't actually damaged Fritz or harmed him in any way, his
behavior has been aggressive towards him. (Periodically, Oscar darts at
him and chases him for short distances.) Fritz respects Oscars space
and goes the other direction, but he doesn't seem to be overly
concerned with Oscars behavior; he doesn't hide from him (he's
been busy exploring his new home); and he doesn't return the
aggressive behavior. He simply starts swimming the other way, and
generally Oscar doesn't pursue him for long. My question is Oscar,
our veteran, eventually get used to Fritz (newcomer), or do we need to
separate them now before any real damage occurs/their own health and
happiness? <I see the pertinent info below> Oh, they live in a 29
gallon (long) tank for now. <This is too small a world for these
two> Oscar is a little bigger than Fritz (approx. 3-4"); Fritz
is the same size Oscar was when we bought him a month or so ago. We are
cycling a 55 gallon tank before we add any fish. <Good> Both of
them have eaten well since Fritz arrived. Fritz acts totally normal
besides being a little more active than usual, which I'm guessing
is due to his new home. It's Oscar that all freaked out. Thank
you!!! Kim <I would move one of the Knives to the new tank once
it's ready... and maybe try re-acquainting them there in time.
Cheers, Bob Fenner>
Ghosts, Knives and something else I have a 55Gal tank with
only an 8in. Black ghost <max over 12"> and a 7in. African
black knife <max 8 to 12">. I am trying to find what other
fish I can put in the tank and how many of each would be appropriate. I
used to have a Silver Arowana but he got way too big for the tank
(27in) so I had to find him a new home. And my albino clown that I
loved died after I took the Arowana out. I have tried Nicaraguenese,
Bala sharks and a Green Terror but the cichlids seem to pick on the
black ghost and the Balas are so twitchy. I am thinking
about trying another clown but it would be nice to have some fish they
weren't always hiding. The tank is pretty lonely and I don't
know who would be most compatible with the ghost. I don't want him
to become fish food <Nothing that will fit in a 55 will take an
8" ghost> or make fish food out of them <Very likely, unless
too large to fit in it's mouth>. Nicole. <The biggest problem
I see is the size of your tank. A 55 is fine for what you have now. But
you would have to add some fairly large fish to ensure they do not
become a late night snack. And if you want a few of them, the 55
shrinks in my eyes. Clown loaches come to mind. They grow large, but
slowly. Some of the larger Cory species would also be safe.
BGK tank mates Hello, I have a Black Ghost Knife that
I've had for about 5 months, about 4 inches. He shares a
60 gal. tank with my Pleco and 2 Platy's. I have a
Fluval 404 for filtration and maintain the water
regularly. I'd like to get bigger, livelier, compatible
fish for the Pleco and BGK. I have a feeling the Platy's
will eventually be food for a larger fish. I'd love to
get an Arowana but think it will outgrow the tank too soon and eat my
BGK. What about Oscars, Eels, Catfish, Red Tail
Sharks? I had a clown loach before but it was very spastic
and swam anxiously in circles and eventually died. What fish
and how many can I add to my tank that would be best fit for the BGK
and Pleco? Thank you. Kristen <Hello Kristen, I'm
afraid for what you want to keep in your 60 will certainly exceed the
capacity of the tank when the fish get larger. Keep your BGK
and your Pleco and maybe add a red tail shark. James (Salty
Re: BGK tank mates Thank you James. If I only add the
red tail shark, is that enough for a tank of this
size? I've heard that I should be keeping 9 fish in my
tank at all times for natural bacterial purposes. Are there
any other fish you would also recommend? Thanks again. <Kristen,
Both the black knife and the Pleco will grow quite large so I am basing
that on future growth of the fish unless you plan on getting a larger
aquarium in the future. The main thing is to monitor your
ammonia levels. When you add a new fish, check these
levels for a week or two to make sure the biological system can handle
the extra load. James (Salty Dog)>
Large Fish Compatibility I have recently bought a striped
shovelnose and a black ghost together and the pet store said they were
compatible, which they are. they don't bother each other. later on
I bought a gold Severum and 2 clown loaches, which the pet store said
that the Severum and clown loaches would go good with the black ghost
knife fish and the shovelnose. nothing has happened yet because they
are all pretty small. but I was telling someone what I had in my tank
and they said that I shouldn't have listened to there advice
because the black ghost knife fish would be fish food sooner or later.
so I was wondering is that true? I do know that the Severum is
compatible with all the other fish but I couldn't find any
information on the black ghost fish. if you can help I would much
appreciate it. thank
Lindsey <Hi Lindsey, I am scared to ask what size tank you
have. These are all fish that get really
large. The shovelnose can get close to 2ft, and the
Ghostknife will not be too far behind. In a large enough
tank you might be ok, I personally do not trust large catfish with
smaller tank mates, they have a tendency to eat them. You
can find more on the Ghostknife at the links below. Best
Regards, Gage http://www.wetwebmedia.com/FWSubWebIndex/knifefishfaqs.htm
Ghost knife with cichlids My son has had a black ghost knife
fish for four years. He is about 9 inches. We, being
ignorant, were keeping him in a <gasp> 10 gal. aquarium all this
time. <yikes that is a bit small...> The last few months he
("Sonar") would stay out of his ghost tube most of the time
and do loops a lot. We increased his feed. <that happens
with Knifefish small tanks seem to have them get restless.> Anyway,
at Christmas I bought him a 29 gal. tank <wow> thinking that
would be wonderful. It came with an Aqua-tech 20-40 power
filter. <I know you're laughing>. <Any filter
is better than none, just have to make sure the water parameters are
okay.> Being ignorant again, in regards to the new tank
cycling. I also bought two convict cichlids to keep him
company. My thinking was they could hold their own with him
since he killed the Neons and Bala shark my son used to
have. <be cautious with any cichlids and Knifefish,
cichlids are nippy things, and if a Knifefish should loose his anal fin
(which is it's only real propulsion) then it is done
for. I try to keep my Knifefish with tankmates that I know
won't bother it.> I used the Stress-coat and
Stress-zyme. The ammonia levels got really high.
<A fish that size is bound to put out some high amounts of waste and
ammonia> I did have a knowledgeable man at Petco advise me on
changing out the water and doubling up on the
stress-zyme. So I did that two times the first week, about
25%. <The stress-zyme isn't really helping the ammonia levels,
it's helping the water additives in your water. The
water change is helping the ammonia levels. So keep up on the water
changes.> I kept asking about using our filtered drinking
water at fish stores and no one seemed too
concerned. We have rural chlorinated hard water but a water
softener, which is what I used for the tank. I now plan on
using the filtered for the next change out. <many Saltwater people
prefer using filtered water for their tanks, nothing saying you
can't use it. Just that it can get expensive.> Should
I still use the chemical additives? <It's not hurting the fish
any, so you can keep doing it, just only add what is recommended on the
package. Good luck with the knife. When
they get older you will have lots of fun. I have a friend
that feeds his ghost by hand.> My main question is should I get rid
of the two cichlids? <I would, they run the risk of
damaging the knife.> Since all this I have spent a lot of time
reading and learning ( a good thing) about these guys. <That is a
very good thing. Research research research! you
will have more fun if you know what to expect.> I think
they are both males. The bigger one (they're both about
3 in) chases the other a lot and so he hides by Sonar which is
sometimes in his tube with him. I just noticed a couple
slits in Sonar's ventral fin now and I'm feeling very
guilty. Other than that they seem to not bother
him. He still does his loops and does come out to feed when
the light is on although he is spending more time in his tube again.
Also, I have learned we really didn't have a biological filter so I
stuck a trickle filter sponge in the power filter where the water flow
out hoping that will help. <any more filtration is better than what
is on there.> I'm pretty sure I'm going to find a home for
these cichlids even though I enjoy watching them. I thought
of just getting rid of the aggressive one. <You can set
up another tank for them. Cichlid tanks are extremely
rewarding. Get a male/female pair, and within 3-4 years you
will no doubt be an expert and breeding them for you LFS!> Sonar is
my biggest concern. Should I do anything
else? Any suggestions you have would be greatly appreciated.
<I would separate the fish, chances are high that they will pick at
Sonar when you aren't around. Give some thought into
setting up a cichlid tank, I'm sure you and the family will really
enjoy them!> Sheryl in Missouri <good
luck Sheryl. -Magnus in New York>
Black ghost Knifefish hi, I need some advice concerning
my ghost Knifefish, I've got a 5ftx3ftx2ft tank(400 litres) I have
1 rather large goby an Arowana 2 angels and 1 Geophagus brasiliensis a
few kuhli loaches and a bristle nosed Plec, all of which seem to get on
fine. last week I fell in love with a ghost Knifefish but since
he's been in the tank I've hardly seen him, or seen him eat
anything. the goby that I've got is very greedy and I'm worried
if the Knifefish getting any food, what should I do???? any advice
would be greatly appreciated, thanks Julie < Your knife fish is
nocturnal and will only come out a night. If you put on a red light
bulb at night you will see him out an about. To make sure he is eating
I would turn out the lights and then feed the tank. They can be very
picky and sometimes only eat live food. I would place some live black
worms in the tank after I turn out he light at least once a week. If
you ever got an elephant nose then I would recommend the same thing.
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
Black Ghost Knife Compatibility, Disease - 10/12/05 Hi -
<Hello.> I have a black ghost knife that was bought recently -
about 5 inches long. He's in a community tank and unfortunately we
forgot about the nippiness (is that a word??) of our Serpae tetras.
<Uh-oh.... Err, *I* say 'uh-oh', but Bob (whom I'm
visiting currently in HI) says there really isn't a compatibility
issue here. I, personally, would be a little nervous about these two
species together.> They have bitten off the end of his tail!! RIGHT
TO THE 2ND BAR!!! <I do agree with Bob here that the Serpaes may not
have been the sole contributor here - please check your water quality.
Maintain ammonia and nitrite at ZERO, nitrate less than 20ppm, with
water changes.> I treated the water with this thing called MelaFix
for any bacterial infection that it might get( I'm in Australia -
hopefully you know what that product is!!) <I do.... and though
MelaFix (extract of the Melaleuca tree, or "tea tree") does
seem to have some mild antibiotic properties, I would not rely on it
alone as a medication for anything severe.... furthermore, I have seen
evidence in my own fishes that it may be a little (or a lot) irritating
to the fish.> He seems OK but I'm worried that he won't
survive without the tip of his tail. Is there any thing else I can do
to help him out?? <Maintain optimal water quality, and (though Bob
and I disagree on the Serpaes!) keep him separate from any fishes that
might bite or nip at his wounds until he's healed. The end of the
tail might not grow back in its entirety, as well.> Also we recently
moved house (about 3 weeks ago) and obviously had to transport tank and
contents. It's a 4 ft tank (180litres) so we took about 1/2 the
water with us and didn't clean filters out etc the ph is 7, the
nitrites are 0.1 and the ammonia 1.2. to me this is high as it is
normally 0. <Dangerously so.> Is there any thing I can do to
lower ammonia levels. I haven't done a water change since we moved.
<Water changes alone will fix this.... and it is urgent that you
do.> Thanks for your help... Tam <Any time, Tam. Wishing you
BGK 1/27/06 Hi there, I have a 35-ish gallon
tank, to be moved up to a larger one soon. I was planning on keeping
some smaller knife fish in it for now, however all my LFS's only
carry black ghosts. I am aware that these grow to ~20 inches, am I
right? <Rarely more than about eight inches overall in captivity>
Are there any other more suitable knifes for my tank? <... would
have to know more re> It is well planted, with driftwood, etc.,
(lots of hidey-holes) and I have several medium sized (~3 inches)
Gouramis, along with some small, 2 inch clown loaches, a whiptail cat,
Pleco, and CAE, <This last may become trouble in time> as well as
some cichlids. <... sounds pretty crowded... S.A. Knifefishes are
not ready "fighters" for food, space> I am planning also
on introducing some Cory cats, African butterfly fish, a dojo (weather)
loach, and possibly (but not likely) an elephant nose. <Then skip on
the knife/knives> I realize the elephant nose should be alone in a
tank of my size, but could I keep more than one BGK (small, ~3-5
inches)? How fast do these guys grow? Will there be any conflict
between them, or will the elephant nose and BGK's electric field
thingies bother each other? <Yes> As well, what about their
feeding habits? Will their nocturnal behaviour keep one or the other
from getting food? I also have some medium sized angels, but I
don't think they'll be too much of a problem...if you guys have
any better suggestions to my choice of fish, please tell me. My
LFS's all tell me that everything will work out fine, but then
again, they would tell me Neons are compatible with knife fish if it
meant I would buy them. I do kind of have myself set on knife fish,
because of their method of movement, but please tell me if you do not
think I have adequate housing for these fish. I realize I am asking
quite a bit right now, so I thank you in advance for anything you can
do for me -Eddy <You need more tanks Eddy... Bob Fenner>
Re: BGK 1/30/06 Thank you for the quick response. I
will be keeping my CAE in a different tank, it is getting pretty
aggressive... I think I'll skip on the knives till I get at least a
50 or 60 gallon, will this do for the knives? I'll stick with the
Corys and butterfly fish for now. Thanks, Eddy <Welcome my young
friend... Have you considered working part time at a local fish
store... or volunteering (if one's nearby) at a public aquarium?