Seems like there's a water quality issue.
1. Large volume water change
2. Pick up an ammonia badge -- they're better for detecting ammonia
3. stop dosing nano a and nano b (they haven't contributed to this, but I doubt you have the consumption required to dose. Let test results drive this)
4. Slow down. You added 4 fish (or more?) in what, a month? In a 15-20 gallon tank (estimating here)? You went from essentially no bio load to max bioload very quickly. It takes time for the bacterial population to adjust to the increase in nutrients.
1. Large volume water change
2. Pick up an ammonia badge -- they're better for detecting ammonia
3. stop dosing nano a and nano b (they haven't contributed to this, but I doubt you have the consumption required to dose. Let test results drive this)
4. Slow down. You added 4 fish (or more?) in what, a month? In a 15-20 gallon tank (estimating here)? You went from essentially no bio load to max bioload very quickly. It takes time for the bacterial population to adjust to the increase in nutrients.