My favorite goldie is isolating himself, so I'd really appreciate some help with how to treat him. I have a 75 gal aquarium, with 3 filters (75 g - 120 g filters), plus 2 large oxygen bars. I do a 50-75% water change once a week. I have 3 orandas, 1 ryukin, 1 black moore, 1 mixed baby, and 1 ranchu. I have had all of these for over a year, except the baby. Two of them successfully mated. My PH is pretty high, around 8.1-8.2. I currently have no gravel in the aquarium, bc I was waiting to move the aquarium once more before getting everything just perfect (we're going through a remodel). My ranchu, who would previously be social and dart around the aquarium with excitement, now spends his days inside the dark castle, completely isolated. He will come out for feeding, but only after a few minutes of me calling for him. I haven't noticed any damaged fins or suspicious spots. He is not floating or sinking, just choosing to isolate himself all the time. Any suggestions on what I can do? He is my absolute favorite. Will update with parameters this afternoon.