It is mostly food competition issues. However, if you have a big comet that like to play rough (or try to mate with the pearlscale), it might knock some of the pearl's scales off. And the regrown scales will be just flat, not pearls.
80 gal FW with 30 gal DIY wet/dry/sump.
9 fancy golds, 1 hillstream loaches, 1 rubber-lip pleco (C. thomasi), 3 SAEs, small school of white cloud minnows, planted.