The black phantom tetra looks like it has 3 individual white spots and that is an issue.
The danio is skinny.
Do a 75-80% water change and gravel clean the substrate every 2 days for the next 2 weeks.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.
Raise the water temperature to 30C (86F) and keep it there for 2 weeks. The heat will kill off the white spot parasites, and the big water changes will help dilute any ammonia in the water.
Increase aeration/ surface turbulence to maximise the oxygen levels in the water.
Reduce feeding to once every couple of days until the filter has cycled in a month or so.
If you post a picture and description of your filter, we can tell you how to clean it.