Ok 1st your test is telling me either you are not cycled or something has happened to the BB. Your amonia is around .5 to 1.0 and 0 trites and trates.
0 trites is good but unless you are heavy planted you should show nitrates.
I would do a 50% water change and then test in an hour. Im going to guess you will be at .25 at this point and need to do another 50% water change. If you leave it as it is your other fish will start having problems. Was the tank cycled before this? Im not an expert so hopefully someone will agree or disagree soon.