Hi folks. This morning I noticed that one of my dwarf gourami's eyes is bulging. I did some search online and it seems to be pop-eye. It's definitely not there the day before yesterday, as I have a clear photo of him taken. Please see the before and after picture attached. I'm pretty sure it's not there yesterday either. I just tested the water, the condition is good: ammonia=0, nitrite=0, nitrate=5ppm, ph=8, temp=80f. The dwarf gourami was newly introduced to my 29 gallon on Saturday. There was a swordtail bullying him. I returned the said swordtail yesterday and the dwarf grouami looks happy except that he does not eat much. What should I do? Thank you!