Best feeding clown fry marine rotifers, brineshrimp to large until approx
8 weeks old, the fanning the male is doing is to oxygenate the eggs, the
sand might just be covering eggs due to fanning. Very hard to keep fry
alive you really need a dedicated grow out tank, no lights on only when feeding, the light on the heater blacked out and all four sides of the tank covered with black paper to keep light out, fry gravitate towards the light and will starve to death chasing a pin prick of light.
Hope this helps.