More information will be helpful. Is that a coral beauty dwarf angel behind? The tail fin of the CBB does not present like a bacterial infection but looks like recent aggression from another tank mate.
How long has this condition been present?
How long have you had the fish?
What other fish are in the tank and how long have they been there?
The white spots on the fins and body are of concern also but not likely related to the damage to the tail. Have you had ich in your tank and have you followed QT protocol with your fish when you got them?