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Yes. Do all tests on it while you are at it. And it's good to test once a month or so as the water folks are constantly screwing with the water chemistry.
Tank water? Daily. Tap water? Every month or so maybe.
Unless your tap water has crazy amounts of ammonia or nitrite or nitrate I wouldnt' worry. I'd change the tank water now though as stated above--- those nitrites are going to rise further and it can be bad news for more fish.