I want to add another fish?

[NanaReefer]

40B/20L sump, almost 9months old.

Current fish, Royal Gramma, Bi-Colored Blenny and Banggai Cardinal. All well established.
I'm wanting to add a Hectors Goby. Can anyone foresee a problem?

Here's my tank.

 

[eatbreakfast]

None of your current inhabitants should bother a hectors goby.