user manual located at
http://download.gigabyte.us/FileList/Manual/mb_manual_ga-b150m-ds3h(ddr3)_e.pdf
yes quite right only 1 sys fan..
easierst way is get a fan controller in your case to be honest you cannot run 5 fans on one header you will burn it out.
the only easier solution depends on your power supply to have standard Molex 4pin plug so you can daisy chain the fan on it, but that means a fix speed for all fan all the time
getting a fan controller is just simpler.