Depends on what's bothering them, I can't really see very well in the pic. In my experience peroxide is too much for some of them, especially if they're already stressed. It will kill any algae growing on them if done correctly. I've always been told to try an iodine dip and it's not a bad idea if you have some. I would do a furan2 dip next and see how they react, give them a couple days before trying though.