Enjoy them!! They are awesome! How many have you ordered and at what size?
They grow as quickly as you allow them. MAin thing is not letting them be/get thin...by thin I mean being able to observe two "grooves " in their back. Fill them up nice and easy.
I feed mine day in day out, a good piece of defrosted fish, which I buy in the supermarket ( I prefere FW fish such as nile perch ) and have it cut in "slices"...A good sized slice feeds my three ( half of it for the monster and a quarter each for the young'uns )
The young'uns don't like the skin and scales around the slice of fish so I have to rip it off. The monster, on the other hand, could eat an ox with horns.
On and off, when I feed it to the aros/knives, they vaccuum some of the shrimp from the bottom of the tank.
BEWARE of high temps. They hate it. By high I mean above 27-28 Cº. I find they like colder waters...
Enjoy