Although I want to get a gator for my plans to build an aquarium, I would caution you on keeping one as I used to run an aquarium and learned a lot from the keepers and how we kept ours.
First off, check to see whether you can actually possess this animal where you live. Many municipalities have laws against crocodilians and if you run amok of the law, you may regret the rescue.
Second, they eat whatever comes their way. We used to feed ours a variety of foods including fish, birds, rodents, and invertebrates. They were never very adept at catching live fish but once in a while they would get lucky (we kept some bluegills with them). Keeping turtles with them works until the day it doesn't - meaning they will eat it if the opportunity comes up or at the very least, take off a chunk of leg or shell.
Third, in terms of feeding, NEVER feed it by hand. Feed sticks are an absolutely essential element of feeding them as if you get them used to eating from your hand or they associate you with food, then guess what, you become a possible menu item for them. It may not be on purpose but accidentally biting your arm off hurts as much as biting it off on purpose. Not trying to criticize, but once they associate you with food you have a problem, especially since they will also lose any possible fear they might have of people. That's why in places where they have gators they tell people not to feed them and not to handle them - this results in loss of fear. Gator farms have no problem feeding their gators as they are all destined to be slaughtered for their meat or skin one day. Many places that keep gators have deals with gator farms to get hatchlings from them and then trade them back in for hatchlings once they outgrow their enclosures. These gators are not released back into the wild, but into controlled environments where they are culled so there's not as much risk in them losing their fear of people. They are intelligent enough to associate colors with feeding (we trained ours to respond to specific target colors so that we could monitor individual's and how much they ate) but they are also wild enough to never lose the reflex to snap at anything that moves. One of my most prized moments was when a gator bit my shoe because I moved it as it walked by. Yes, an odd moment to prize but it was pretty fantastic since it did not pierce my shoe and let go after it couldn't roll me - it was only about 40" long at best.
The average person will never have enough space to house an alligator throughout its life and the average zoo or aquarium will never take one in because they simply don't need them or have space to take them in. As much as it would suck to have it be eaten eventually or turned into a belt or boots, your best bet is to call an alligator farm and see if they'll take it because it will outgrow anything you can keep it in within a few years.
All of that aside, they are pretty awesome and if I could get the permitting and zoning exception, I would have one in a heartbeat but I also have plans to have a public aquarium where I could house multiple adult alligators in a safe setting in the future.
