You may have better success if you leave the eggs in the tank, Add a small amount (a few drops) of acriflavine or meth blue--might stain, Then move the fry when they are a bit bigger and more robust. Remove the adults, seperate males/females and spawn again in 10-14 days. Many fish have a problem with the eggs becoming calcified (particularly tetras and fish that like soft water) so breeding them frequently may help with that.