I'm goin to buy fishes today and my daily water change is on saturday. Should I change water today?

What I do when I buy new goldfish is I put them in a separate tank (or large tuple ware if you don't have a separate tank) filled with half water from the old tank and half de-chlorinated tap water. I leave the fish there for a week to make sure there is no disease. After a week, I move the fish with a glass or large cup, pouring out as much water as possible back into the tank they were in before putting them in the new tank. I also change the quarantine tank's water every day and stir the water up before i feed them for oxygen, because I only have one filter.

The reason for using half the water from the established tank is the bacteria that breaks down the ammonia and nitrite from the waste.

if you cannot quarantine the fish, then add them directly after a 30-40% water change, making sure to trash almost all the water in the bag before adding them to the tank water. After adjusting the fish to the tank temperature by floating the bag, of course. By minimizing the amount of water from the pet store you minimize the chances of a parasite or disease, like ich, from transferring to your tank.

NEVER do a full water change ALWAYS do a PARTIAL water change which is like 25% of the water every two weeks to a month but two weeks is best

Its actually bad to change your water that much because of stress...also how clean are the oceans, lakes and rivers?

yes, its adviseable, bc ur not suppose to disturb them 4 72hrs after bringing them home, it may stress them out n they will die