The Equipment

To keep your goldfish happy and healthy you must choose a suitable tank for them. Make sure your tank is not to small as the fish will grow if they are babies. If they are adults make sure you have a nice big tank, anyway,  so that the fish can swim around it. The bigger the tank the happier the fish.

Fish can be VERY messy creatures as they tend to leave their droppings almost everywhere. This is why you should have a filter so that it can prevent the tank being a poop pile. Also, if you have a filter the  water doesn't go cloudy.    

OWater out of taps is treated with chemicals to make it safe for humans to drink but not particularly safe for fish to swim in. Tap water contains cholorine. Cholorine is a gas which dissipates into the air over time, so water that has been left standing for a few hours is better for fish than that straight out of a tap. There are also chemicals that you can buy to neutralise the additives in the water so just add a few drops to make the water safe for your new fish. If you add too many there will be too many chemicals. Its best if you put it before the fish are in the tank