I have three danios, two blue longfin and one zebra. They've all gotten along fine for months and months, having fun chases around the tank and generally enjoying themselves. A couple days ago, I noticed one of the blues was paler. Now, he looks much paler than the other two fish. I don't really understand why, since if it was anything like low oxygen or high parameters, all the fish would be affected. Last night, he was eating and playing normally, but today, I've noticed some "being bullied" type behavior, maybe. He is hiding behind an ornament a lot, and doesn't seem to want to chase as much. It's just strange because he was happy to chase everyone around before and vice versa. I understand that pale tends to mean stressed out, so I'm really trying to figure it out. If it was sickness, I feel like there'd be at least one other symptom, so I don't think it's that, either... I read a different forum which said it was pretty much out of your control and to just keep an eye on the fish in question, but I'm mostly wondering if anybody else has faced something similar. Thank you. P.S. Since I'm asking more for if this has happened to you than solutions, I'm not going to post parameters or anything, especially since I think it's unrelated. Any comments would be appreciated.