Pajama cardinal nipping at acro

[bucfan]

Noticed my strawberry shortcake acro was losing tissue. Could not figure out why till last night when I noticed my pajama cardinal nipping at it. Did not know they go for corals. Anyone see this before and what could be the reason?

 

[lakeviewink]

I've noticed some fish will nip sick corals or corals that aren't doing well while leaving the healthy ones alone.