that is an impellar shaft they are not that expensive you lfs should have replacement shaft mine sells them for about 5.00 you can get them offline cheaper
my big tank leaked so im down to a smaller one and this guy is way too big im downsizing tank will trade for ? let me know what you have. needs to be gone the next day or 2 at most to keep him from stressing out im in tampa fl e mail jscott@s2mc.com