Tank size, ammonia, nitrite, nitrate etc? Any tankmates? From the bulging eyes bit I'd guess popeye, but not sure. Does it look a bit like those bubble eye goldfish do?
Then I'd treat for popeye. But as I said, what are water stats, tank size etc? Its best to find out why its diseased than have all the others getting ill.
Look in the... can't remember what its called, index of pinned topics. In the emergency section. To clarify, are the eyes bulging outwards or is three a 'bubble' of skin on/around the eye? And you seem to be skirting round telling us about the tank
OK then, now not sure if its popeye. Could be something more serious. I'll have a look, I'll edit in a sec.
After having a look, both internal bacteria and tuberculosis (SP?) mention poping eyes being a symptom. I'd wait until someone clever comes on who knows these things, diseases aren't my speciality
I'm not real sure how to best treat popeye, but I've found in the past year or so that when my fish have issues, the majority of the time a 50 percent water change done again in about 2 weeks seems to clear things up.