Tricky fish these.
I had a very active one that was brilliant to watch when it was growing out in one of my tanks.
They can and WILL kill anything that takes their fancy, so as all of my tanks house some quite rare fish, and knowing that they simply are NOT suitable in home aquaria, it went into the pond.
At that point it became quite uninteresting as never get to see it.
Throwing live Koi into the pond just saw a spilt second splash and all over.
Many people ignore advice given on these fish, and end up regretting it.
They DO get VERY VERY large, VERY quickly and are a pain in the #16##### to keep.
My advice to the OP (from a real owner) is unless you have the means to house it properly (at least 9ft x 4ft x4ft) right now, pass it on.
Anything smaller than that is just going to make an unhappy fish, that will not be as active and happy as it should be.
Also don't forget the crazy filtration. These things poop like dogs when they get over 2ft. It is big and messy.
You were warned...