Once they get free swimming start feeding brine shrimp naupali (spelling ). If you want you can try some sort of finely powdered flake. Not all the fish will take it. It took me a few days before all my fry were taking flake...
Also, as soon as the fry start swimming, you may notice your adults eating them. Mybe it was just me, but my female ate about 1/2 the batch while I was at school and there was only about 30 when I got home
BBS are best , we have been breeding for over a decade now and to tell you the truth we have used everything on the market and found that BBS are the preferred food for Angel fry. Be sure to use the BBS right away since the nutritional value is best the first two days after hatching , after that the are mainly water unless you feed the BBS which is not worth it .