You are looking at 1000 lbs in one spot. What you need to know is if the spot you've chosen is supported adequately. A wall on the perimeter of the apartment building would be stronger, assuming the floor joists were running the correct direction.
Asking the apartment complex if you can put a 100g tank in your apartment may cause some issues. They don't like aquariums because they worry about leaks and flooding for the ceiling below.