First of all, like you said, breeder nets aren't fine enough to keep bbs in.
Second,angel fry need very clean conditions, especially at the beginning. Unless you plan on doing major daily water changes on the tank they are in, you will have problems with bacteria. Also, how do you plan to clean the net daily?
Third, angels need room to grow, lots of fin in compairison to a small body. I keep 300 in a 10 gallon for the first few weeks, that's 30 per gallon, or 3 per 1/10 of a gallon, 12.8 ounces. If they are raised in cramped conditions they will have some deformities, usually chopped/stunted dorsal fins.
Fourth, being as small as they are, if their larger tankmates see them the won't be thinking "Ooo, baby angels". They will be thinking "Yum!! Baby angels!". Even if they can't get through the net, they will batter them to death.
Tolak