Yeah, yeah that would be a good thing lol. Ammonia (fish poop, old food and more) as well as Nitrite can be extremely toxic and deadly to all fish if not kept at zero...sooo yeah that's a good thing to look at
Ideally you should get the API Freshwater Master Testing Kit, that has both pH and high pH testing kits which is good to keep an eye on as well, and then it comes with the ammonia, nitrite and nitrate testing kits too. You should do a partial water change whenever ammonia or nitrite go over zero because they become toxic.
How many gallons is your tank and how long has it been set up?