Some people I think have led others on to believe that all Carapo knives are very aggressive.. They are towards any other knifefish, but I have never seen any of them pester other fish.. I have a number of Carapo knives that have been seperated and are currently living with other fish. I am unsure how the large G. Tiger pictured would react to tankmates, but he is intelligent and knows the difference between my hand and food. I don't think these fish honestly have the teeth or violent nature to kill another fish.. It however, may pester other fish during the night time hours.
I plan on having one in a monster stingray tank in the future. They are one of my favorite fish.