Why wasn't Sisko called "captain"

[Photon]

on the Defiant, when it first arrived.

Dax was when she commanded it.

 

[Finn]

well duh

 

[indolover]

it's naval tradition to call a CO Captain, despite his/her actual rank. Chief O'Brien once said this in the show.

 

[C.E. Evans]

IMO, while it's a tradition in some navies to call the commander (or even acting commander) of any ship "captain," regardless of their actual rank, I don't believe it's a mandatory kind of thing in Starfleet. The practice of doing so on the Defiant may not have started until Sisko decided to start doing it at some point...

 

[SpyOne]

In fact, apparently in the US Navy tradition is to call the CO "Skipper" if he isn't a Captain in rank as well as position.
Your Starfleet May Vary.

 

[Hober Mallow]

In fact, apparently in the US Navy tradition is to call the CO "Skipper" if he isn't a Captain in rank as well as position.
Your Starfleet May Vary.

Who really wants this guy on the Defiant bridge?

 

[Photon]

In fact, apparently in the US Navy tradition is to call the CO "Skipper" if he isn't a Captain in rank as well as position.
Your Starfleet May Vary.

Who really wants this guy on the Defiant bridge?

hey little buddy...huh huh lock those torpedoes on that Dominion ship"

 

[Ensign_Redshirt]

If we're talking about Season 3, I think it would have been a bit to confusing.

While commanding the Defiant, Sisko would have been adressed as "captain", while on the station he would have been called "commander". You got to stick to one title/rank. I guess that's the real-world reason anyway. Maybe it also works as in-universe explanation.

(When commanding the Defiant in early Season 6, Jadzia hadn't any position on DS9, so no problem here.)