how big is the "breeder tank"? is it actually a separate tank or one of those breeder boxes? if its the latter, don't leave her in there long. if you have plenty of plants and places for the fry to hide, you'll most likely be able to catch a few and transfer them. those breeder boxes are too small for anything but a guppy to use really, and even thats pushing it. those thing can actually stress her out enough to abort, its better to either put her in an actual tank set up for this or to just let her have them in the main tank and what survives, survives........