"looks as if slime was melting off his body"

I think this requires a little more than some ABBA!!

I don't know much about fish but I lost 3 goldfish in 2 weeks last summer and learnt pretty quick a few things.

Anyway I did a quick google search and found this page with diagnoses for skin problems

"http://www.fishyfarmacy.com/symptoms.html"

It says it could be a fungal or bacterial problem.

Could you go to an aquatics centre (somewhere where they atually know about fish unlike most petstores) and expalin everything and get some meds for him?

Sarah