If some are surviving, then there's a chance they'll survive without the filter.
Are you doing water changes with water from the parents' tank? Daily changes (I use a turkey baster to change water in really small tanks) will help.
If you have an airpump/airstone, you can add that to their tank, too. If you have any live plants, throw some in there with the fry. There are lots of microorganisms on plants. I've also read that a snail or two can help, as they produce somthing on their shells that fry can eat.