Maybe I am just fortunate in that when I get fry, they muck in with everyone else, eat whatever is there...no specialised foods, just what everyone else is given. I thought I had just the one BN baby...nope....at last count (and they are really helpful cos they all hang out together) I have at least 10 of the blighters, all around an inch long, very healthy and no feeding issues with them or the Ram or Cory fry....they all seem ridiculously healthy and hearty.
As for generalisations, I would estimate that only around 10 to 20% of fry actually manage to get to the "I can see you" and able to stand up for themselves stage. Most get eaten by parents or other tankmates, some die due to genetic defect and some are the proverbial runts who didn't get a good start from hatching and are basically weaker and die.
Your fish are still quite young, they are very inexperienced as parents...and you sometimes find that what appears to be very attentive parenting (since you are new to the world of babies yourself aswell) possibly isn't as attentive as maybe they will be once they have had a few more batches and have figured out what they are meant to be doing.
It is very rare that you will get a 100% survivability rate on fry and there are a multitude of reasons why they don't make it. As you become more experienced and you try different feeding methods...and the fish themselves mature...then you might get an average 20% survivability if you are lucky. The more tetchy or demanding the fish, quite often the lower the percentage.
