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FAQs on South American Knifefish Stocking/Selection

Related Articles: Knifefishes, Gymnarchus Black Ghost Knife, Electrogenic Fishes,

Related FAQs:  BGK Selection, Knifefishes 1, Knifefishes 2, Knifefish Identification, Knifefish Behavior, Knifefish Compatibility, Knifefish Systems, Knifefish Feeding, Knifefish Disease, Knifefish Reproduction, Electrogenic Fishes,


Hypopygus lepturus - Slender Tail Knifefish    1/26/12
Hi Neale,
In proceeding with my tank I have decided to target the Orinoco River Basin and have upgraded to 38 gallons. I have also found in my book "The Complete Book of the Freshwater Aquarium", that there lives in that area the above mentioned knifefish. This fish apparently on reaches 4 inches and would fit well with my stock of fish (Keyhole, Bolivian Ram, Clown Pleco; though I may have to pick some larger tetras than Black Phantoms). However I cannot find any further information anywhere on these guys. Do you have any knowledge of them or where they can be obtained if they are in fact suitable for my aquarium.
<I've not seen these traded. The usual small knifefish of the UK trade at least is Eigenmannia virescens, the Glass Knifefish, a slightly delicate, gregarious species that works well in species tanks in groups of 6+ specimens. Being easy targets for nippy or aggressive fish they're best kept alone, but very peaceful tankmates such as Hatchetfish or Corydoras can work. Less often you see Sternopygus species, such as Steatogenys elegans. They're similar in requirements, but bigger, around 15-20 cm in length, and slightly easier to keep with carefully chosen tankmates. All these "Glass Knifefishes" are inhabitants of fast-flowing streams with lots of oxygen and excellent water quality, and generally they feed on invertebrates rather than fish. Plan around them accordingly, and realistically, they're subjects for a single-species tank rather than an oddball for a community. I can't think of ANY knifefish that is really a community fish, though both Xenomystus nigri and Apteronotus albifrons have some potential in mixed species set-ups, if used with care.>
Also since I have upgraded to 38 I was considering adding the Cockatoo cichlid in. What are your thoughts.
<Sure; these can work well in community tanks, though they are shy and easily bullied.>
Again I am sorry to bother you so much but I respect and appreciate your input and I would rather bother the heck out of you now than in 8 months if the plan nose-dives. Thanks again Neale.
<Welcome, Neale.>

Black Ghost Knife in a 55g tank?  1/5/07 Hi, <Hi Iain, Pufferpunk here> My name is Iain and I am thinking about getting a Black Ghost Knife but I have been told they are hard to look after -is this true? - And if yes how do you look after them? <I think the biggest problem keeping these odd fish is feeding them.  Most will only eat live worms.  Mine hides, unless I am feeding & then it darts out of it's cave, eats & goes back into hiding.> Before I get my Black Ghost Knife I would like to know would it be ok in a tank (48x18x12) with plants, rocks and a decorative barrel? <I would say minimum--a 90g tank for these large-growing fish.> Also will it be ok with theses fish listed:- 1- 3x Silver Sharks      3-4 inches 2- 2x Plecos               3-4 inches 3- 1x Albino Shark       2-3 inches 4- 4x Silver Mollies       1-2 inches 5- 10x Zebra Danios     1-1.5 inches 6- 10x Penguin Tetras  0.5-1.5 inches 7- 10x Black Neon's     0.5-1 inches Thank You for taking your time to read this Question <I think your tank is stocked quite well as it is.  The BGK has also been known to eat small fish.  Watch the adult sizes of those Plecos (if common Plecos, 18") & "silver sharks" (not quite sure what species those are--Bala sharks?  Also grow quite large, 14").  Great job for someone of your age!  ~PP> From, Iain MacPherson - aged 13

Re: No to BGK, FW Oddball fish?  1/5/07 Hi, <Hi again> Thanks for the information - so are you saying I should stay away from BGK- if yes, can you recommend any other oddball fish? <There are other smaller knife fish, like the brown knife & glass knife.  You will need a consistent live supply of worms for them though.  As far as other oddballs--I like the African butterfly but you must be sure to cover all of the tank at all times or they will jump. Same for the rope eel--another cool oddball.  Your best bet would be look through the WWM website & do some research on different species you may like.  ~PP> Thanks for taking your time to read my question. Iain MacPherson, aged 13

That's Black the Knife Hi guys and dolls.... <Hello, Sabrina with you today> My question refers to the black ghost Knifefish.  I saw some at my LFS for $25!! Expensive but they are really cool. Now I know they are supposed to be black with a white stripe running down the top, and a white ring on their tail. The LFS had about 9 of them, but some of them had a yellowish stripe instead of white. Is this normal or are they sick? Thanks for the info. <I've seen older ghosts have yellowed looking stripes as well as a graying body, but when young, they should be quite black with rather vivid white markings.  Do keep in mind that this is a shy, nocturnal animal, very aggressive within its species (one to a tank, basically), and reaches a whopping 20 inches....  A very large tank would be quite necessary to house one of these beautiful beasts - and no aggressive fish, nor any small fish, could be housed with it.>

In Love with a Chocolate Ghost Knife Hi Bob, <Hello Susie> I have recently (three weeks ago to be exact) set up a freshwater (20 gallon) tank. My daughter has four aquariums, and has been quite successful with her fish. I went to her "fish place" to purchase a few new fish and fell in love with a chocolate ghost knife. <A beautiful and intelligent species> The owner of the shop assured me he would be fine with my mollies (5), guppies(6), Platies(2), Cory cats(2), red tail shark(1), silver stripe shark(1), leopard algae eater(1),and Neons(4). He is about five inches long and he is beautiful! I would really like to keep him, but now I have read on some internet sites that this may be bad. He seems to be fine, and prefers a rock cave to his clear tube. My questions are : <Well... it will likely eat all baby livebearers... and your Neons in time... And the "sharks" prefer different water quality... hard/alkaline versus softer/acidic... and the worst fact to relate... your tank is way too small for all these fishes.> 1.Did I make an incorrect purchase? 2.Will he kill my other fish? 3.How does he find his food (bloodworms are what the guy suggested). 4.Does he absolutely have to have live food, and if so, what should I give him. <Not live food, frozen defrosted meaty foods will likely do... offered right after "lights out" for the Ghost...> I would really like to keep him, but I do not want to do the wrong thing. <There are many other things to know about this fish and its relatives... they don't tolerate much in the way of standard fish medications... are electrogenic... Bob Fenner> Susie

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