Animal Stories - Black Ghost Knife Fish


Animal-World Information about: Black Ghost Knife Fish

The Black Ghost Knifefish is the most well known species of knife fish in the aquarium industry!
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Ryan MacDonald - 2017-04-13
Hi Everyone, I have a 4 year old 14 inch black ghost knife fish.... Help he has something wrong with him. last night he was looking fine.today he has bloated up in the abdomen and looks like something is starting to protrude out just under his mouth? is this a disease or a blockage? have pic's but not sure how to upload to site. any suggestions?

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Charles House - 2016-08-31
I recently bought a BGK and he spends alot of time by the water heater It's 76° fahr.in the tank.Should I turn up the water temperature just for the BGK.All my other fish are fine with the temp.

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Peter - 2016-08-11
Will a Albion sailfin pleco be okay in the same rank as a black ghost knife fish ?

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Brandon - 2015-10-19
I have an 150 gallon community tank with a koi Angelfish, a rainbow shark, a spotted south Africa leaf fish, a pictus catfish, a featherfin catfish, a twig catfish, a sailfin pleco, a black molly, a halfmoon betta, a otto catfish, and a 3 spotted gourami. Can i keep a bgkf with these fish safely?

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  • Brandon - 2016-06-22
    No black ghot knife fish cant be with those i asked the same thing to my fish expert aka alamo AQUATICs they said that when black ghost get bigger they will try to kill the gourmia
    Black ghost knifes get a maximum of 20" to 18" 3spoted gourmia are territorial so are angles so you can i just depends on how agrassive the knife fish is some are nice and some are not. YOU CAN BUT I WOULDN'T
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KnifeFish - 2015-11-11
Can i keep one of these with a pair of Johannis and a convict cichlid, thanks! -KnifeFish

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  • Ian - 2016-01-05
    It depends on the size of the BGK compared to the cichlids, as well as their temperament. I just added a 3' BGK to a 120g cichlid tank that had 6 malawai cichlids whose sizes ranged from 2' to 3' and it is doing fine. That being said, I also added 2 zebra danios and 4 Giant Danios the same day, before I added the BGK, as a distraction. The 2 zebras were killed, but 3 of the 4 Giants survived, and my BGK wasn't harassed once. I've heard convicts can be nasty, so it may be a gamble, but with a BGK and a Red Tailed Shark roaming the tank floor and a few dither fish swimming at the top, no part of your tank will be boring.
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KnifeFish - 2015-11-11
Can i keep the knifefish with some Cichlids (Electric Blue Johanni Cichlid 2X, Convict Cichlid 1X) The Johanni Chiclids are male and female and the rest of the fish are peaceful.

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Rickey Stiles - 2015-05-23
i have recently got a black knife fish and was wondering if anyone noticed there's sleeping on its side or is mine defective lol thanks for reading

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  • Lyn - 2015-05-24
    I'm not an expert, but I have found my fish in odd positions at times, but not all the time. If your fish otherwise swims around and is eating then I would say that it's OK. Good luck. I'm absolutely hopeless but I've done OK with my two and they are now huge. I'm thinking that I'm going to have to buy yet another aquarium (I already have 5) just for them.
  • Clarice Brough - 2015-05-31
    Yeah they can and often do rest on their sides, your fish is not defective:)
  • Charles R. - 2015-07-01
    I was very much interested in the BGK's and when I went to purchase my first one it was only pushing 3's but the behavior was so abnormal I got concerned. but yes they do often have weird resting positions, which I now find very interesting.
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Zoey - 2014-02-05
Please can some one help me my cousin got a angel fish 2day and her black knife keeps attacking it is this normal?

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  • Clarice Brough - 2014-02-05
    A Black Ghost Knife can get aggressive with its own or similar species, possibly like those nice flowing fins of the angel! Making sure the tank isn't too small, these guys reach 20' in length, and that there are plenty of hiding placed all around the tank can help.
  • Lyn - 2015-05-24
    Unlike the other poster, I've had no problems with mine with Angels and Silver Dollars. Weird that behaviours are so different!
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Dewin Arnold - 2015-02-24
Hiii , I got around 8 BGK fish around 3 to 4 cm in size for my aquarium , my aquarium is around 4 feet in length and 3 feet in height ...... I love the fish but my tank looks empty .... so can you suggest suitable tank mates for my BGK fish.......also I would like to know the max size the BGK fish grow .

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  • Clarice Brough - 2015-02-24
    The Black Ghost Knife gets to be a big fish, so tankmates need to be too large for it to eat. Almost any  non-aggressive medium to large fish can work, as long as they are not nippy. A school of Silver Dollars or large tetras like the Congo Tetras and Bleeding Heart Tetras. Possibly even Giant Danios might work as long as they don't get pesky. Use the 'fish finder' feature to help you come up with even more ideas.
  • Lyn - 2015-05-24
    I have had mine with Silver Dollars and Angel Fish without incident. I've been reading up on these fish recently (as I think I've got a female either full of eggs or full of gas!!), and they can grow up to 50cm!!!! This would have to be in absolutely ideal conditions in a really large tank. My two, in a community tank of 120 litres, have grown to approximately 20 and maybe 30cm respectively. Good luck.
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Cherie Adams Dodd - 2015-03-03
Knife fish and Frontosa as tank mates???



Hello fellow fish lovers :) I am fairly new to fishkeeping and I am asing for advise in relation to my two beautiful black ghost knife fish which I purchaced with a second hand 2ft tank about 7 months ago. One was 7cm and the other 3cm. They have been upgraded to the three foot tank and spend a bit of time in the 4ft tank and have grown and seem very happy. ATM they are in 3ft as we just purchaced 2 frontosa fish, 18cm male & 13cm ?female. We took the knifes out so we could quarentine and medicate the frontosas and other new fish at full dose (melifix). Reading the pH levels the frontosa seem to need pH8-8.5 and the knifes pH6-8. My long winded question is... What do you all think about the knifes living with the frontosa? We are waiting to pick up and fix a 7ft which they would all move into. The 4ft also has 5 venustus, 1 old and wobbly maingano, 4 female red empress and a male tangerine peacock. The Knifes have been ok in the high 7.5-8.5 pH but what do you all think about the happiness of the frontosa and knifes together??? Thanks for any help and advice :)  

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  • Clarice Brough - 2015-03-04
    This is a repeat to your comment under the Frontosa... but I'm still excited, so re-posting it here:)

    Well I must say, I'm really excited about all your fish. I can tell you are a great aquarist:) Of course there's no guarantee, but I think they may be okay with each other (unless you find out you have a male Frontosa that decides to get territorial - but still, he may not be aggressive to existing tankmates!) You might be better off keeping the other African cichlids in the 4 foot, or at least have it available if they decide to get testy with the ghost knives and Frontosa. But I say try it, and be ready to adjust as needed!
  • Lyn - 2015-05-24
    I don't know frontosa,but Google tells me they are a cichlid. If this is true, I have heard that cichlids can be quite aggressive, while knives are very calm and peaceful. I wouldn't risk it personally. Also, you would have to be VERY careful with your pH and carbonate hardness with the pH requirements being right on the brink for both species.
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