Someone has goldfish with dropsy. I know it fatal but i read that in very early stages you can treat it with Epsom salt. So i am trying to figure out what is the dosage. If you google it they give you like 1/8 of the spoon and they don't even write about water changes. I got confused. I know all instructions for betta but not sure if it the same amount for goldfish
Dropsy isn't really a disease but a symptom. It can be caused by a number of things including bacterial infection, parasites, and kidney failure. All the epsom salt is going to do is ease the swelling. You need to figure out the cause and treat that. You can read more about dropsy here Diagnosing by Symptoms and here Gold fish Diseases (scroll down to other goldie health issues).