[speckled trout]

I have a tank that contains various montis, acros, and numerous soft coral. Everything's been normal for the last year or so until I started noticing that some of my montis (plating/branching) had begun to show minor bleaching. Not my acros, just most of the montis.

I thought this was strange and began looking for any possible culprits like nudibranches, without success. There aren't any and I don't see any other obvious parasites on them.

Also, everything else looks normal. Any ideas about a pathogen that would be so specific to the montis?

Thanks-Mike