As Rob stated, they will usually lay a few more than they actually raise. You may see a few of the embryo simply not make it to hatching or come out with deformalities. I propose that the larger clutrch sizes is to make up for these 'errors'. I once had a pair of long term captive bri bris that went through 3 clutches before getting it right. The 4th clutch contained 7 eggs but only 4 had survived the internal development and only 3 had made it as neonates. My current almirante pair had laid a clutch of 6 but only 3 made it to the water. All in all, don't expect them all to make it....feeding eggs to a large group is probably very taxing on the females.