I have has several "bamboo" or "cat" sharks. Most likley what you have is Chiloscyllium Puntatum as it is the most common one available. THey are pretty hardy, not very agressive but will eat smaller fish and inverts. Don't put fish like large angels or triggers in with it, they pick on sharks and rays. They are mostly nocturnal but will be active in the day time when feeding the aquarium. They are stripped as juviniles but are mostly solid tan as adults. They normally will grow to about 36" or so, perhaps a little bigger but not much. I'd say it'll be ok in a 120 (4'x2'x2') for a couple years but as it grows it will need a larger tank like a 6 or 8 foot by 2 or 3 foot size to be comfortable. THey are not picky eaters, shrimp, squid, smelt, etc., mixed in with a multi complex food like ocean nutritions formula 1 or 2 is perfect for these guys. Don't feed it just one item, keep it varied so it gets everything it needs in it's diet. No gold fish or other freshwater feeders, that kind of diet is harmful to them in the long run. Do partial water changes often, they can be messy. Don't use medications in the water with sharks & rays, they don't tollerate parasite meds very well. If you don't have it yet, when you get it home, slowly drip water from your aquarium into the water it was sent home in. They shock and die pretty easily when transfered from one body of water to another to quickly. I do this with most all my fish but it's really important with sharks & rays.
Joel