Well a sudden development with Carp today.
A chap came over to pick up a juvenile Vieja regani that I unsuccessfully tried to introduce to my big tank. Anyway I mentioned about Carp to him while he was there, and he wanted him ! He has load of space and tanks, and is an experienced cichlid breeder so I was happy that he would be able to give him a good home. I netted Carp out to show him (as he has been in a white plastic tub), and he looks waaay better than he did just a week a go. Really starting to fill out. Fins are nice again. It's a real pity I just couldn't keep him.
He has been eating really well over the last few days too. With plenty of top notch poop too, so I'm confident that any gut problems he had are now behind him.
Anyway, a good result for all !!!
Good luck Carp !