Man of fish
I'm Interested in.... ----|> that
[ why I corrected myself below. Accidentally hit reply not edit I also said I wasn't sure in my first post
All of those rams are basically German Blue Rams. Your pH is fine, they actually prefer pH below 7, not what man of fish suggested.
Being german blue rams (the gold and electric blue are just color variants) they are very very fragile to water conditions. You need to not only look at pH, but also your ammonia, nitrates, nitrites, and water hardness. Even the slightest amount of ammonia or nitrite in the tank can cause big issues. How long has the tank been running for? How large is it?
I'd also look to make sure that none of the other rams are picking on the one that is struggling.
I may not be helping but a quick google search (or others) can confirm this but I think rams need a higher/lower ph than that. I read on google gbr s like the ph around 5-6 and couldn't really find info on the others.
Oops I hit reply instead of edit ....