I'm guessing he has the same infection the guppies had. Whatever it is, it kills really fast. He was stress stripey, pale, and a little bloated on Wednesday night. All day yesterday he kept the stripes but he ate a bloodworm and he was his normal active self. I kept a towel over him thinking it was some trauma from the water change on Wednesday morning. He kept coming to see me on the edge that wasn't covered by the towel. I checked his params again and they were fine (0/0/10). Last night he was active, swimming around and being cute.
This morning I woke up and found him on his side on the bottom, barely breathing. I'm going to replace everything that I have (siphon, bucket, nets, etc). He's in a breeders cup so he can get to the air better but he's barely there. I did a massive water change in case something got into the water but I doubt that's the case. It's too much like what happened with the guppies. I'm so sad.