Is this a pinched mantle?

[Larry L]

Not sure what is going on with my Derasa, it has been like this for a couple days . I've had it for several years and this is the first I have seen anything like this. I inspected the shell and can't find anything on the bottom or around the edges. Any idea what might be going on, and what I should do about it?

 

[Tahoe61]

Is one of the near by LPS sending out sweeper at night?
Try changing out your charcoal and or adding more charcoal than you usually use. If it advances and it's not a near by coral causing the issue nor a fish nipping then I would seriously consider a FW bath (match pH and temp), 10 minutes is about average length of time.

 

[Larry L]

@Tahoe61 thanks for the tips.

Is one of the near by LPS sending out sweeper at night?

Good idea, I will move it away from neighbors and see what happens.

Try changing out your charcoal and or adding more charcoal than you usually use.

I don't run carbon. What are you thinking it would help with?

 

[Tahoe61]

Running charcoal and changing it out appears to assist in the treatment of PMD.

 

[Larry L]

Ok, so I've started running carbon and changing it out every other day (also saw that recommendation in another post). I am not seeing any improvement, but at least it does not appear to be getting any worse. Should I just keep an eye on it, or consider doing the freshwater dip?