I'm *not* an expert, especially with cichlids, but I've kept fish on and off since I was a kid and I feel pretty much positive that is not ich. Also the fact that only your Acei's seem to be having issues is another clue. It could be a sickness of some sort that is not Ich, but again, I don't think so.
In the very last photo you can see the tail fin of one of them at the very top of the frame and it is all shredded. I feel about 95% sure that one of your Acei's is a bully and is beating up the other's, picking at their scales and nipping their fins. He/she may also show some damage since of course the other fish will try to defend themselves. Observe them closely for a while, find the bully and segregate him in a qarantine tank or breeder box until you can rehome it.