Is it Marine velvet?

[Dr. Reef]

If your tank does not showing any ammonia in multiple tests from 2 separate kits then your biological filter is working and no need to add anymore equipment.

 

[Big G]

You can test the ammonia badge by holding the badge above the mouth of an open bottle of ammonia. It should change color rapidly.

 

[Umair]

thank you all for your assistance and guidance, was able to successfully quarantine remaining three tangs with CP and prazipro as per the guidelines mentioned on this forum.

starting with new batch of fishes. wish me luck

 

[HotRocks]

Good deal! Glad to hear it!