The Blue Fleet was the name for the Andorian division of Starfleet. (Ships whose officer contingent and crew are entirely Andorian.)
The majority of the Loknar-class frigates were assigned to the Blue Fleet and the USS Loknar was the first ship commissioned into the Blue Fleet, serving as the flagship for many years.
The core of all squadrons belonging to the Blue Fleet were formed by the Andor-class since its introduction. (FASA RPG module: Federation Ship Recognition Manual)