  We present a sample of $X$-ray selected candidate black holes in 51 low mass
galaxies with $z\le 0.055$ {and mass up to $10^{10}$ M$_{\odot}$} obtained by
cross-correlating the NASA-SLOAN Atlas with the 3XMM catalogue. {We have also
searched in the available catalogues for radio counterparts of the black hole
candidates and find that 19 of the previously selected sources have also a
radio counterpart.} Our results show that about $37\%$ of the galaxies of our
sample host { an $X$-ray source} (associated to a radio counterpart) spatially
coincident with the galaxy center, in agreement with { other recent works}. For
these {\it nuclear} sources, the $X$-ray/radio fundamental plane relation
allows one to estimate the mass of the (central) candidate black holes which
results to be in the range $10^{4}-2\times10^{8}$ M$_{\odot}$ (with median
value of $\simeq 3\times 10^7$ M$_{\odot}$ and eight candidates having mass
below $10^{7}$ M$_{\odot}$). This result, while suggesting that $X$-ray
emitting black holes in low-mass galaxies may have had a key role in the
evolution of such systems, makes even more urgent to explain how such massive
objects formed in galaxies. {Of course, dedicated follow-up observations both
in the $X$-ray and radio bands, as well as in the optical, are necessary in
order to confirm our results
