If you didn't cycle the tank thats the problem. If you did, then you don't clean your tank often enough..for your fish it should a min of ever other week but its better every week
HELP ! I have a 10 gallon tank with 3 tetras, 2 guppies and a bottom feeder. AMMONIA level is too high and i don't know what to do. I recently did a water change to get rid of excess food, conditioned it, and added some water clarifier.