Candidates running in city elections this year were required to file campaign finance reports this week, giving us a pretty good idea of who the leading contenders for a handful of open Bronx seats will be. Of course, it’s still early and candidates will continue to emerge over the coming months, but those who filed this week are already off and running. Here’s a look at the most interesting City Council races in the Bronx and who’s leading the fundraising game in the 11th, 15th, 16th and 12th districts, which should all be competitive this year.