This will depend on what is wrong with your fish.
For the best health of your fish, you need to first make sure you have enough room for them, so for goldfish that means 20 gallons for one goldfish, plus 10 to 15 gallons per additional goldfish (that means at least 30 to 35 gallons for 2 goldfish).
You must have good filtration on the tank, and do at minimum a 50% weekly water change in the tank as long as you are not overstocked.
Fish pellets or flakes made specifically for goldfish. Regular fish food doesn't give them the nutrients they need. Occasionally, you can give them a little hard boiled egg yolk as a treat :)
Yes they were telling VERY tall tales that day and IDK why. I myself have the FAINTAIL GOLDFISH and the BOTTLENOSE DOLPHIN and they both have separate underwater rooms BUT the FAINTAIL GOLDFISH has reached after 10+ pets. I have 113 so you never know.
No, sorry.
if the gills are clogged the fish will die with out cure
Metronidazole is commonly used in cases of certain stomach infections in some fish (in particular Discus) it is not a specific cure for parasites.
fish is good hehehhehheh
it depends on how bad the condition is and what kind of fish it is, it is better to go with a white spot cure.
yes
You should be able to buy prducts for any pet shop called something like 'Fungi cure' or 'Multi cure'
Unfortunately it may not be possible; it's dependant on the health of the fish before it was electrocuted.
Yes. Food rich in Vitamin A, C and E, a high fiber diet and fatty fish that contains omega 3 can cure acne.
There are some. I believe your beta fish's tail is torn because of fin rot. There is a cure for that in pet stores.