They are also call'ed Maroon sharks, i have 3 of them i got when they started about 1 inch long, and now are a good 10 Inch long they grow fast with a good food supply, they are very calm, i dont even think they eat feeder gold fish. they get along great with my Oscar and bala sharks.
they are about 4x the size of my balas tho lol. and my Oscar is super friendly i had a albino cory, blue grom and some Tetra in the same tank and he did not go after them once. but i have takin them out n put them in a new tank now