In the photos and the video he was sedated after being treat with phenoxyethanol - this is an effective anti fungal treatment (what we first thought it was, before it visibly started “opening”) and also a known fish sedative. His breathing was laboured as he was very sleepy!
I have contacted “The Deep” in Hull and hope that they will respond swiftly, I have also contacted other places, but I believe “The Deep” could be my best shot. An aquarium of their size and reputation are almost guaranteed to have seen this before (I hope!)
Obviously, I will keep you guys posted!