Well I haven't tested the water parameters yet, but it's a 90 gallon tank, and I do 25% water changes weekly. The tank is rather understocked; just the 2 angels, a few neons, a few rasboras, 5 scissortail rasboras, a guppy, 2 plecos, and a few danios.
Maybe he just ate too much.....the other fish, including the other angel, all look great so I didn't think that disease was a factor...but yeah, I will keep an eye on them....
I can definitely rule out eggs though? I'm not at home right now so I can't check, but the bulge was pretty huge last I looked, equal on both sides, and I'm pretty sure it follows the contours of the angel's lower body, but is rounded otherwise.
maybe I will take a picture later and post it!