What the water looks like is not a good indication of water quality. While cloudy water does usually mean something is wrong, your water can have dangerous levels of toxins but still be crystal clear. You will need to test your water for ammonia, nitrite and nitrate to figure out if it is "clean". What most of us on the forum use is the API liquid master test kit. Don't waste your time on the strips- they are very unreliable. If you are not aware of the cycling process this is also something you should read up on. A cycled tank along with regular water changes and appropriate stocking is the way to keep a healthy tank.
Like other posters said, angel fish and gold fish do not belong in the same tank. Angels are tropical fish and Goldies are cold water fish. Also each gold fish needs 20 gallons of water because they can grow to enormous size and have huge bioloads (produce a ton of waste) so if you have 4 goldfish hopefully your tank is at least 80 gallons.
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