Researching Black Ghost Knifefish

feemia

feemia

AC Members
Mar 20, 2007
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South-Central Washington
I’ve been researching Black Ghost Knifefish since my husband some a tank of them this weekend and asked if we could get one. I’m hoping that someone with experience with BGK can clarify some conflicting info and help fill in the blanks.

TANK SIZE
I’ve found recommendations ranging from 50 – 200 gallons minimum tank size. The most commonly recommended minimum is 75 gallons, which I wouldn’t mind upgrading to because I like the size and shape of the tank. The 60 that I currently have is 24” deep, which requires me to reach in up to my shoulder if I need to reach the bottom of the tank. I’d like the 75 because it’s isn’t as deep.

GROWTH RATE
Most sources say that they reach 20”, but they grow slowly. I did read a couple of articles that say that for the first year they grow very quickly, up to 12” and then the growth rate slows down considerably. I’m wondering how long I could keep one in my 60 gallon before I have to upgrade.

TANKMATES
All sources agree that they will eat any fish small enough to fit in their mouth, which is a pretty big mouth, but don’t give any details about how big the tankmates should be. I know that small slim-bodied fish such as guppies and neons wouldn’t be safe, but what about corys, bristlenose plecos, platies, flame tetras, kribs, and my husband’s newly purchased red-eyed tetras?
 
I did a search of threads over on Monsterfishkeepers and they're confirming that 55-75 gallons would be sufficient and they do indeed grow slowly after the initial 12". They also say that BGK rarely reach over 15" in captivity.
 
from my own experience with having one (3" to 9" in 6 months) even if they don't feel like eating something, they can still kill it. their mouths open a LOT wider than you can imagine from just looking at one in a tank. wait until you see one yawn - it's a big surprise. mine would bite guppies in half or bite their eyes out if he didn't feel like eating them at that moment. then they would be ignored. apparently they have a bad habit of biting the eyes out of larger tankmates, but that's just from researching online. i haven't had that experience personally, but i wouldn't put mine with my angels and test it out.
 
feemia said:
I did a search of threads over on Monsterfishkeepers and they're confirming that 55-75 gallons would be sufficient and they do indeed grow slowly after the initial 12". They also say that BGK rarely reach over 15" in captivity.
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keep them in a small tank how do you think they can reach full size. i would say 180 gal 72x24x24
 
I had one that was eventually returned to the store, it grew to 10" from 2" in about 8 months. Very aggressive, it killed my apple snails, a cory and two angel fish. My advice would be to avoid the fish entirely.
 
I was told when I went to purchase one that it would kill any other bottom feeder that are in the tank and unless the other fishes are bigger than he is it would most likly kill any fish in my tank, including my Kissing gourmis, I ahve heard nothing but nasty things about them. THough it sucks cause they are such beautiful fish!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
shin0r said:
I had one that was eventually returned to the store, it grew to 10" from 2" in about 8 months. Very aggressive, it killed my apple snails, a cory and two angel fish. My advice would be to avoid the fish entirely.
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are you sure you had a ghost knife? i'm pretty sure they rarely reach 24" in the wild, let alone in aquaria. maybe you had a different knife species?
 
FreshFish82 said:
I was told when I went to purchase one that it would kill any other bottom feeder that are in the tank and unless the other fishes are bigger than he is it would most likly kill any fish in my tank, including my Kissing gourmis, I ahve heard nothing but nasty things about them. THough it sucks cause they are such beautiful fish!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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You didn't specify what bottom feeders would be killed. IMO, I doubt it when it comes to certain species. Without specifying, then this is not any more helpful at all. I have never seen this attitude in my BGK nor from others I know who have them. True that it can eat small fish but kill big fish who may be able to retaliate well?
 
wataugachicken said:
are you sure you had a ghost knife? i'm pretty sure they rarely reach 24" in the wild, let alone in aquaria. maybe you had a different knife species?
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It could be a clownknife. Those guys are mean!!:lipssealedsmilie:
 
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