Banjo catfish ill

[Smyles90]

Hi

I got 3 banjo catfish last month
Kept them in a 350L with sand and tank mates

I noticed 1 of them wouldn't bury themselves anymore and stayed in the top of my plants. He had a small white circle on his back so u quarantined him and treated him with methylene blue dabbed onto the wound and put esha 2000 in his hospital tank. Treatment was repeated daily but on the 5th day he had dies

Now a second banjo seems to have the same issues, but this time on his fin
I've quarantined him and done the same treatment but instead of esha 2000 I've used myxazin

Now on day 3 and it's just got worse, now how bones are poking out

Got told it was either a bite thats got infected or some disease
Just odd it's now happened only to catfish and one after the other