Same! I feed my fry a similar mixtureWhen I got some platy fry that's what I fed them along with flakes, colour pellets, and freeze dried brine shrimp crushed into a powder and mixed together. I found it worked quite well. I was only able to save 2 fry and they are about 2 months. They have great colours and have grown quickly. I also put some of my floating hornwort in the breeder box with them and they picked peices off them. Then once they got a little bigger a started putting balanced veggies in the box and just fed them brine shrimp and blood worms.
I'm no expert on raising fry and mine were accidental babies but this method worked for me.