Roseline Shark cotton mouth?

[Oli]

Does this look like cotton mouth on one of my Roseline sharks? I have had them for a couple of months, and to my memory, this one has always been visibly “paler” and had more pink than red compared to the others. I’m only now wandering if this could be the dreaded columnaris?

 

[Oli]

B

 

[Colin_T]

How long has it had the white mouth for?
If it's had it for more than a few days and it hasn't gotten worse, then it's probably a fat lip (swelling) from swimming into something.

It doesn't look like Columnaris to me.

The pale colouration could mean it's female or more likely due to the white substrate.

 

[Oli]

I recall seeing the pale area for at least a couple weeks now and didn’t think much of it. I’m worried about columnaris because I intended to use this tank and filter for discus pretty soon…

 

[Oli]

You can see that in the other fish, they have a bright red mouth that goes into a bright red stripe. This one has a pink mouth that goes into a pale red stripe?

 

[Colin_T]

If it has been like that for a couple of weeks, it isn't Columnaris. That would have killed the fish weeks ago.

Make sure the fish aren't being spooked or startled.
Have the room lights on or open the curtains for 30 minutes before turning the tank lights on.
Have the room lights on before you turn the tank light off and leave the room light on for 30 minutes after the tank light is off.
Make sure there is nothing hard or sharp they can swim into if they panic.