Yeah there are some crazy looking knife fish out there any of them can be raised for a good while in a 125gal but if you go with one of the bigger species you will have to rehome or upgrade your aquarium after a while.
Here's a few pics of my current and past knife fish
Sent from my iPhone using MonsterAquariaNetwork app


Here's a few pics of my current and past knife fish
Sent from my iPhone using MonsterAquariaNetwork app

