Fish gasping for air at water surface is a sure sign that something is wrong with the water, basically means the fish is in toxic water unfortunately.
What you may need to do is to read this article first, this explain the nitrogen cycle and how to cycle your fish tank properly to make the water safe for your livestock that goes into this tank.
Cycling Your First Fresh Water Tank What is Cycling and Why is it Important? Fish waste, and especially fish breathing, plus uneaten food and other organic matter breaking down in a tank all produce Ammonia. This can quickly become toxic to fish if it is allowed to build up to any measurable...
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Essentailly it means the fish produces something called ammonia simply by breathing and pooping. This ammonia is toxic for fish.
So we then 'cycle' the tank to deal with this ammonia by growing good bacterias to consume this ammonia, which then the becomes nitrite, this is also toxic for fish but on a lesser scale than ammonia so then a new type of bacteria grows to deal with this nitrite and this become something called nitrate, nitrate is also toxic but the least toxic of the three elements. Nitrate is then dealt with by us, the fishkeeper, doing water changes once or twice every week to get rid of the nitrate. So then this becomes the cycle.
One other important factor is the fact tap water has chlorine and this is not good for fish / livestock so we then need to add some tap safe conditioner into the tank to get rid of this chlorine.
First thing would do is to do a large water change, at least 75% with water temperature being fairly close to tank water as possible also make sure you add dechlorinator / tap safe to the new water into the tank.
Then try and purchase a more accurate test kit.
@Slaphppy7 has mentioned thi and linked to an API test kit product, that is not a bad test kit for beginners as is good value for money and is fairly accurate as long as the tests is carried out exactly as instructions state.