itching

I had about 4 baby blue tangs and they all have itch once they go in my main tank. I quarantine them for a month . They’re my last fish to put in my DT and nothing new. Any idea on what I’m doing wrong? It’s a temporary 65g tank and he’s about 3”

My bursa trigger scratches his right side on the sand and rock often after eating. Video is attached. He is eating well and has no visible signs of ich or scratches on him. Please let me know if you have any ideas. Thanks in advance.

Debating if I should take action: my panther grouper has been itching on the sand bed, only occasionally the past couple months, but lately it seems more often he has an itching fit (swimming on his side against the sand 1-3 times). Id bet hes doing it more than once a day. No other visible...