Haha, me and my friends want to save up to buy all the lobsters and set them free!!! haha
But ummm, all lobsters do is walk around, so in a 75 hes probably going to just sit in the corner for the most part and maybe walk around a little at night seeing how they are nocturnal. But put in a giant rock in there if you do to give him something to hide under. Make sure the lid is held down tight, and he will most likely only accept live foods. I used to care for one at a market, although this one was kept as a pet because it was a blue lobster. I had to go out and catch green crabs for him to eat, it can be easier to get him to eat by cutting the crab, still alive, in half and then dropping it next to him in the tank. I eventually got mine on frozens but that was after a few months.