  We report here measurements on a dark magneto-optical trap (DMOT) of
$^{85}$Rb atoms using an optical nanofibre (ONF) with a waist of $\sim$~1
$\mu$m. The DMOT is created using a doughnut-shaped repump beam along with a
depump beam for efficient transfer of cold atoms from the bright hyperfine
ground state ($F=3$) into the dark hyperfine ground state ($F=2$). The
fluorescence from the cold $^{85}$Rb atoms of the DMOT is detected by coupling
it into the fibre-guided modes of the ONF. The measured fractional population
of cold atoms in the bright hyperfine ground state ($p$) is as low as
$\sim$0.04. The dependence of loading rate of DMOT on cooling laser intensity
is investigated and also compared with the loading rate of a bright-MOT (BMOT).
This work lays the foundation for the use of an ONF for probing of a small
number of atoms in an optically-dense cold atomic cloud.
