Hole in tail

[fishforu]

My Coral Beauty has suddenly developed a hole in its tail and the hole is gradually getting larger. It can stll swims normally and has its normal appetite.

Will the hole eventually close-up/heal on its own or should I be concerned?
What is a possible cause?

Its tankmates is a pair black and white clownfish.

Thanks.

 

[SkullV]

Fin rot. How is your water quality? You can usually get it to heal up with pristine water and good food.

 

[fishforu]

The tank is 30 gallons and I perform a 5-8 gallons water change every week.

However, I am currently experiencing a hair algae outbreak, but will soon run SWC Phoshate and Nitrate removing Bio Media.

Hopefully the fin rot will disappear afterwards.

Thanks.