When I had a few different species of knife fish, African knifes, black ghost, transparent, I noticed that all of them liked the same tube. Even though I had several tibes in the tank in different locations.
After looking into it more from some of my breeder friends and such, I learn that most if not all knife fish are actually blind. Their eyes only detect light. It's their electrical sensors that allow them to see. That would explain alittle better why the clear pipes work.
And because of the size of the tank with filteration, the knifes felt safe and secure in the same pipe. Only when they got bigger they started to find their on places.
I also noticed in my experience that the African brown knife likes having another knife in the water. Mine hangs out with my royal clown knife. Same was true when I hady black ghost knifes. The only one I had some problems with was the chocolate ghost or brown ghost knifes. They seem to be more aggressive then the typical knife.
Thought I'd share.
