Hi Mama
I have never seen anything like this on an angel before. I would suggest an antibacterial control measure, to stop any further infections.
It certainly does not look like a wound injury, unless it is a secondary infection.
Sorry I could not be much help.
Nice to hear three of the fry are still alive.
On a happier note, I have been taking pictures of my fish and other pets, for the last few days, and should be able to post them over the weekend. (it is a friends camera, and he will put the pics onto cd for me). Might just make it in time for FOTM.