Like every thing else, there are several ways to raise fry. I guess none is wrong, unless the fry don't survive. I prefer to give a mixed diet for different reasons. It is better for the fish, and they will eat better for anyone else who gets the fish when they are grown.
I start the fry on Liquid Fry #1, and Vinegar Eels for the first 3 days. Vinegar Eels and Microworms from day 3 to day 7, and then Micro worms and BBS till the end of week 3. I then start adding frozen Daphnia to the diet, along with the MW and BBS, and slowly bring in frozen BS, as they get bigger. I smash the frozen BS, so the pieces are smaller. If I could give 1 suggestion that would help most people, it would be to feed the MicroWorms 15 min. before feeding the BBS. By doing this, it helps to prevent swim bladder disorder. The fry are partly full from the MW, and they don't gorge themselves with bbs. This is something I picked up from several top breeders, and it worked for me when I tried it. One way of deciding if things are working for you, is the percent of fry that make it to the growout tank. I think doing the MW, then BBS...along with feeding frozen Daphnia at 3 weeks old, was the key to raising more fry. Of couse clean water is vital. It can't be too clean for fry. Clean is not the same as sterile. In case some don't know...the fry put off a chemical to stunt the other fry, so they don't grow as fast. I knew this, but didn't carry it on to my 55 gal growout tank. I figured there was enough water to make a difference. When I was told by Ralph Tran that the chemicals was still affecting the fry, I started changing water in that tank more frequently. There was a big boost in growing when I did. Clean water, and a variety of food will do more for you than anything else you can do.