Black African Knife?

[Gryph]

My husband wants to buy a 55 gallon aquarium for our mutual Christmas gift. I've talked him out of oscars ("Look at the price of this 120 gallon, honey! They eventually need those!"), but he'd really like a knife fish. I hear that the black African knife is very hardy and easy to keep.

What would be good tank mates for a black African knife fish in a 55 gallon tank? I'd like to avoid gouramis, as I already have some of those, and the larger tetras don't do much for me. Are there any good chiclids? How about angelfish? I understand that the tank mates should be more on the docile side, and not so small that the knife will eat them.

Please have fun with stocking ideas! You're all so creative, I enjoy your thoughts.

 

[cabbspapp]

ive never owned a black knife, but a few brown knifes, and if what i heard is true, the black knife can get over 1 foot long, so a 55 would eventually become too small for the knife as it grows. i imagine angelfish would go good with the knife, because they are peaceful fish, but will eat a fish that is small enough to fit in its mouth, because they are carnivores. the knife will probably hide until lights out because they are nocturnal fish. but whats better about a bigger tank is that the water chemistry is more stable than in smaller tanks.

 

[Lonewolfblue]

Another idea is a smaller eel. You definitely want a larger fish so they don't get eaten. Not sure how it would be, as I've never kept them, but silver dollars get pretty big. Any thoughts on those?

 

[Lonewolfblue]

Maybe even tiger barbs.....

 

[Fruitbat]

The 'Black' African Knife is Xenomystus nigri. It is one of the smallest of the 'knife fish', reaching lengths of close to a foot (though one this size would be very rare....they generally do not exceed 8 inches). They are relatively secretive, nocturnal predators and require some sort of hiding place to be truly happy in an aquarium. X.nigri can be distinguished from the other African Knife Fish (Papyrocranus species) because X. nigri lacks a dorsal fin.

I keep my Xenomystus nigri in a tank with Bush Fish (Ctenopoma and Microctenopoma species), some smaller bichirs (Polypterus species), African Butterfly Fish (Pantodon buchholzi) and some Synodontis catfish. Some people report that you can successfully keep multiple specimens of X. nigri together successfully but I've never had more than one adult in a tank without some serious squabbles. Tankmates can include pretty much anything that isn't small enough to be swallowed or that isn't overly aggressive.

-Joe

NOTE: I've included pictures of both Xenomystus nigri and Papyrocranus afer below. Note the obvious dorsal fin on the P. afer and the lack of the same fin on X. nigri. If the fish you're looking at is Papyrocranus afer then the entire equation is changed because P. afer is a much larger and, in my experience, more aggressive fish than X. nigri.

Xenomystus nigri

Papyrocranus afer]/b]

 

[Acer]

its true that they "might" get that big but like was said above its rare in captivity, also they take a very long time to grow from what i've read.. i dont want to repeat what was said above about anything that wont fit in its mouth but you might want to avoid most agressive bottom dwellers as they might see him as a threat to their "territory" and to their food supply.. also they navigate more through sonar because they dont have the greatest eyesight, so a clear plastic tube would give them the feeling of security while still allowing you to view them... i think this would make a good center piece fish.. i would like to eventually have one and place it in my 55 gal that currently houses 3 pairs of juvi angelfish... hth

 

[Hrafnkel]

I own a Xenomystus nigri and highly recommend them, very fun, intriguing fish. Very prehistoric looking. I don't think that Xenomystus nigri uses sonar like some knife fish, mine seems to have excellent eyesight (and they -do- have large eyes, compared to Black Ghost Knifes).

 

[Acer]

sorry i was talking about the Black African knife fish..

 

[Hrafnkel]

Which one is that? I've heard the name assigned to several species.

 

[crazycat]

NICE fish fruitbat! i'm dreaming of a 100g birchir tank with a black ghost knife (sigh). as soon as the sticker shock from my 125g community tank wears off, and i can come up with some more funds...

 

[Acer]

Hrafnkel Apteronotus albifrons Black Ghost Knife Fish

 

[Gryph]

These are great replies, thank you! X. nigri is the one I'm looking at, for certain. He'll be the centerpiece for sure, but I'd definitely like some active, colorful fish for when he's hiding.

 

[nomadofthehills]

Do you mean the black ghost?

 

[Gryph]

Nope, I mean the black African knife, Xenomystus nigri. The ghosts are beautiful, but harder to take care of.

Speaking of the African knife, how big is "too big to fit in his mouth"? Three inches? Four? I've never asked one to open its mouth, so I'm not too sure on size.

 

[Hrafnkel]

Mine isn't full grown but he's large enough to eat my bloodfins and has never once given them a second look, even though he swims all over the tank at night. I think their reputation for being excessively carnivorous is undeserved.

 

[Fruitbat]

Well.....having kept a few dozen of the African Black Knife Fish (Xenomystus nigri) over the years...I can offer a few more observations. I've found that X. nigri individuals vary greatly in their tolerance for other knife fish and in the degree to which they prey on other fish. In general, however, I am willing to say that adult X. nigri do not overly like other knife fish (and occasionally other types of fish as well) and that putting a much smaller fish in the tank with an X. nigri is murder waiting to happen. A 1- to 2-inch fish just isn't a safe bet in a tank with an African Black Knife. Anything over about 2 inches should be OK. If you really want to see a Xenomystus put a world of hurt on something, drop an earthworm in front of it!

The lone Xenomystus that I currently have took an instant dislike to my male Banded Bush Fish (Microctenopoma fasciolatum) and chases it mercilessly whenever the two happen to bump into each other. No physical harm is ever done to the Bush Fish but it certainly won't remain in the vicinity of the Knife Fish for long. I've also kept fish like the 'kribensis' (Pelvicachromis pulcher) with the African Black Knife without too many problems.

By the way.....Papyrocranus afer is more commonly called the African Featherfin Knife.

-Joe

 

[Gryph]

This is terrific! Thank you so much!

Of course, in all this research I've fallen in love with the Brichardi, but those will have to go in their own tank. They're just too touchy about breeding, and I wouldn't want the knife attacked.