You have fry already? well in this case, the food will probably float through the net, so it might be a waste. And yes, you can feed them with shrimp when they get older.
Either way, we have a load of little black mollies swimming around in the java fern
And they are growing steadily eating just the same as the adults do
Some tropical fish flakes and occasional blood worms and cucumber
(We usually don't notice them in the start anyway, so they find food somehow.)