Camarilla Tremere Slave:

I know the clan is and needs a Tremere to take a action, but does this mean the Gargoyle IS from the Camarilla sect and not Independent?

Yes.

Name: Fidus, The Shrunken Beast
[BL:U2]
Cardtype: Vampire
Clan: Gargoyle
Group: 2
Capacity: 4
Discipline: for tha vis
Camarilla Tremere Slave: Fidus gets +1 stealth on undirected actions. -1 strength. Flight [FLIGHT].

Fidus's sect is Camarilla.
Fidus can use his Slaveness when Muaziz (Camarilla Tremere) or anarch Muaziz (Independent Tremere) is acting.

Just a clarification that the -default- sect of gargoyles is independent, but the sect of the gargoyle (or the vampire of the master clan) does not have anything to do with how the slave rule works, it only cares about the clan of the master vampire, not the sect of either. The 'Camarilla' in the text just refers to the sect of that individual gargoyle, just like how any other vampireh as their sect listed in their text, its not linked to the 'tremere slave' part of the text.

I think someone suggested splitting it into "Camarilla. Tremere Slave" to make it cleaner, which was a good idea.