if I get a feather star, will it get attacked by my aggressive fish?

[BilboB]

I have a 125g FOWLR with multiple triggerfish, a lunare wrasse and an emperor angelfish. I'm worried they'll bite the feather star's arms...

 

[Subsea]

First and most important: Is your system capable of supporting the feeding requirements of this filter feeder?

@BilboB
Second: Are you serious about this?

Overview

Feather stars (crinoids) are notoriously difficult to keep in home marine aquariums and are generally considered non-sustainable for casual hobbyists. They are passive filter feeders that require constant, heavy suspension-feeding—often needing live phytoplankton and zooplankton dosed multiple times a day—which leads to severe water quality issues. [1, 2, 3]

“I'm worried they'll bite the feather star's arms...”
No worries, they will not bite the arms, instead, they will eat the whole thing.

Overview

Yes, triggerfish will absolutely eat feather stars. Feather stars (crinoids) are closely related to sea stars and urchins, which are natural prey for many triggerfish species. Because feather stars lack a hard, thick exoskeleton and cannot escape fast enough, they are highly vulnerable

 

[BilboB]

OK, thanks.