In an example implementation, a fluid supply assembly includes a printhead assembly and a carriage comprising a quick-release, hand-operable attachment mechanism to removably attach the printhead assembly to the carriage. A fluid conduit interconnect is rigidly attached to the printhead assembly by a tool-operable fastener. The fluid conduit interconnect is to connect to a fluid conduit to communicate printing fluid from an off-axis printing fluid supply to the printhead assembly.