What fish is this?Its turning black.

[Qi rong]

Hi, recently I been noticing that this specific fish is turning blacker and blacker.I got this fish half a year ago.Please let me know what fish is this.

 

[Qi rong]

The picture is the before and after image.

 

[Sharkbait hoohaha]

This looks like a blue fin damsel. They turn black as they mature.