buy a test kite dude. You need them for any fish in ur tank. A set would be great include ammonia/nitrite/DH/PH/CO2 all this r really needed if u want ur angel to be happy. You have to know ur water quality before you can addjesting them. Ops sorry co2 test kite ain't nessarry if ur tank ain't planted my mistake.
I know what a test kit is!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! its juz that im a kid and i dont have money to buy a test kit..... my parents wont buy for me..