IMO, you could add a small CBB, but do remember they get to be 8" in length, so you'd either have to find it a new home at some point, or eventually upgrade to a VERY large tank. Also, the CBB will eat other corals in your tank depending on what corals you keep.
I have soft corals, LPS and SPS and my CBB does not touch any of them
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Steve
“The most important decision you make is to be in a good mood.”
― Voltaire