I always recommend doing a fishless cycle if possible.
That looks like a 56g column tank to me. Normally I'd say a tank like this is just asking for angelfish but I'm not so sure that's a good idea with your pH (and presumably the hardness that comes along with it). It would, however, make a cool tank for African rift lake cichlids. The floor space isn't huge but you could still have a nice colony of yellow labs in there. Get a really big rock pile right in the middle, stacked high so that the fish make use of the higher levels of the tank, and it could be a really neat setup.