Also, I think you should research your tank. What size tank do you have? I suggest you look into carrying capacity, which will keep the ammonia down in the future. Also, you said you have four neon tetras. I suggest if you have enough room you get at least two more neon tetras after the ammonia settles down. Tetras are a schooling fish, and a higher number f them will make them feel safer and curb aggression. If you have a tank that holds under ten gallons of water I suggest you get a bigger tank. The main chemical you need to worry about removing from tap water is chlorine. Chlorine is added to the tap water to kill bacteria that would kill humans, but it is harmful to fish. Chloride, however, is a chemical the human body uses to maintain correct metabolism and maintain acid-base balance.
Neomeris
Neomeris