Hmmmm... they do appear to have a faint preopercular mark, but proximus should have horizontal stripes in the tail I think. They don't look like G. argyrostictus at all IMO.
Do the fish have a black throat under their gills? They look a lot like my G. brachybranchus with the exception of the tail markings... brachys have blue spots on a red tail, but yours appear to have vertical lines. I'm trying to find pictures of mine as younger fish to see if the tail started out striped and then turned into spots as they grew, but I don't think so...
I'm also thinking maybe G. dicrozoster. If they are, their fourth and fifth vertical bars will fuse to form a Y shape. It's hard to see the bars clearly in the pictures.