Should I top off 2nd carboy

I transferred to the secondary fermenter today. The carboy is not filled all the way to the top of the neck. Should it be topped off with water to fill it all the way or leave it as is? It is currently filled to the point just short of where the carboy starts to taper off.

leave it as is. a little head space is OK

That’s what i thought. I just wanted to make sure i checked before it was too late.

thanks.

it should outgas enough co2 to provide a protective shield over the beer.

viewtopic.php?f=1&t=115070

From yesterday.