We report the discovery of a very diverse set of five low-surface brightness (LSB) dwarf galaxy candidates in Hickson Compact Group 90 (HCG 90) detected in deep U-and I-band images obtained with Very Large Telescope/Visible Multi-Object Spectrograph. These are the first LSB dwarf galaxy candidates found in a compact group of galaxies. We measure spheroid half-light radii in the range 0.7 r eff /kpc 1.5 with luminosities of −11.65 M U −9.42 and −12.79 M I −10.58 mag, corresponding to a colour range of (U − I) 0 1.1-2.2 mag and surface brightness levels of μ U 28.1 mag arcsec −2 and μ I 27.4 mag arcsec −2. Their colours and luminosities are consistent with a diverse set of stellar population properties. Assuming solar and 0.02 Z metallicities we obtain stellar masses in the range M * | Z 10 5.7−6.3 M and M * | 0.02 Z 10 6.3−8 M. Three dwarfs are older than 1 Gyr, while the other two significantly bluer dwarfs are younger than ∼2 Gyr at any mass/metallicity combination. Altogether, the new LSB dwarf galaxy candidates share properties with dwarf galaxies found throughout the Local Volume and in nearby galaxy clusters such as Fornax. We find a pair of candidates with ∼2 kpc projected separation, which may represent one of the closest dwarf galaxy pairs found. We also find a nucleated dwarf candidate, with a nucleus size of r eff 46-63 pc and magnitude M U, 0 = −7.42 mag and (U − I) 0 = 1.51 mag, which is consistent with a nuclear stellar disc with a stellar mass in the range 10 4.9 − 6.5 M .