Fry have a high mortality rate in the wild less so in aquaria but if you have ctfish of any type then you're providing a very healthy high nutritional food source for them. Depending on the size of the tank and species you're keeping some should make it through. Invest in some liquifry food for them. Pour it in and the bits and particles will cling to the rock and substrate for them to feed.
If you can catch any and put them in a smaller tank then you'll be able to feed properly and ensure growth. The best way is sometimes to isolate the brooding female and then remove her back to the main tank when the fry are happy.