I cannot see anything from that photo. The individual fish may or may not have a problem...could be internal injury from being netted, or something else.
I would strongly suggest you get another six rummys. I've no info on the tank size, so I hope it is sufficient--one thing is length, a 30-inch/75cm length tank is minimum for this species as it does like to swim end to end a lot, 36-inch/90cm would be preferable as minimum. But this species does much better (health) in larger groups, and 12 is about minimum. I had 21 in my 4-foot tank for years; I gave them to another aquarist when I moved because I could not have the 4-foot tank just smaller tanks, and I miss them, they are one of my favourite characins.