Any idea what this is?

[Dieboldly]

saltwater fish didn’t have this white marking till recently. What is it?

 

[spotfin]

Is it just on one side? Is the fish stressed in the tank?

 

[Gill Blue]

Could be a heater burn.

 

[Dieboldly]

Could be a heater burn.

That’s probably the most logical reason! I didn’t even think about it. When I first got him, he loved hiding behind the heater for whatever reason. Now that I put the suction cups on the heater, he can’t get back there. That probably was it because he’s always swimming around and eating.

 

[Dieboldly]

Is it just on one side? Is the fish stressed in the tank?

It was on only 1 side. No stress. He’s the only fish in the tank along with an anemone

 

[Dieboldly]

What’s the fishes name? Like what kind is he

 

[spotfin]

It is some type of tang. And is a very small one at that. Hard to tell what species.
Can you get a close up picture of its side to better show that spot?

 

[tlindsey]

Possibly a juvenile Kole Tang but just guessing.

 

[RocketGarStar]

Possibly a juvenile Kole Tang but just guessing.

It's definitely a juvenile SOMETHING.
I'm looking through now... Bignose unicormfish...? The spots looked like that to me. Or an adult ringtail tang. Bristletooth Tomini tang? I'm really quite useless for saltwater at this point.