So, sahuagin all possess the shark telepathy trait, which states:
Shark Telepathy. The sahuagin can magically command any shark within 120 feet of [it/her/him], using a limited telepathy.
It's not part of the actions section for the sahuagin, and no action is given. Should this be like the beastmaster having to use a bonus action each round thing, or more like the UA feat that lets you use a bonus action once and give a command that lasts a minute, or something else altogether?