Black Arowana are one of my top 5 fish. Had lots of them. They ,like most S.A. fish like soft, aged water. I use oak leaves and branches to soak in my rain barrels to get the water softer. Sounds to me like you could keep one ok at this point in your fishkeeping career. Just a little pricey nowadays. Use to, you could get a 3" Baby Black Arowana for $25-30.00. About $100.00 now. I've kept them with Wolffish successfully a bunch of times. Only when the arowana is 2-3x the size of the Wolffish though. Your Black Curupira is will tame down and realize that you are it's food source shortly. The waiting is terrible. I'm glad the Aimara Wolffish that I bought from Wes came out of the bag ready to go at any comers. I was scared about getting one that was extremely spooky , like I've read about. Surely yours won't take long to get right. Just beware of feeders, they can get your fish sick faster than a 2 dollar woman of ill repute. .