I am new to aquarium fish. Could anyone help me identify these species? I found it in local aquarium store in Chengdu, China, where I am visiting.

It is about 6 inches long, it has a black body with a couple of white stripes on the tail. It has a very long wavy fin on the bottom and can easily rotate in water as well as swim upside down.

Thanks in advance for advice or resources to use in case of finding unknown fish species.

Black long fish that can swim upside down

  • please try to add more information about the fish,is it freshwater or saltwater in the tank. – trond hansen Nov 10 '18 at 13:09
  • Based on the size of the bubbles coming out of the airstone at the back, I'd guess freshwater. – Henders Nov 19 '18 at 10:39

They're called knife fish. There are several varieties, the ones in your photo are called black ghost knife fish. The common varieties such as ghost knife fish are fairly easy to care for, but they need tank-mates who aren't going to pester them. Some of the larger species such as clown knife fish are completely unfit for the all but the largest home aquarium as they can reach more than 36in.


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