Context : A planetary nebula ( PN ) candidate was discovered during FORS imaging of the Local Group dwarf galaxy Phoenix .

Aims : Use this PN to complement abundances from red-giant stars .

Methods : FORS spectroscopy was used to confirm the PN classification .
Empirical methods and photoionization modelling were used to derive elemental abundances from the emission line fluxes and to characterize the central star .

Results : For the elements deemed most reliable for measuring the metallicity of the interstellar medium ( ISM ) from which the PN formed , [ O/H ] \sim - 0.46 and [ Ar/H ] \sim - 1.03 .
[ O/H ] has lower measurement errors but greater uncertainties due to the unresolved issue of oxygen enrichment in the PN precursor star .

Conclusions : Earlier than 2 Gyr ago ( the lower limit of the derived age for the central star ) the ISM had Z = 0.002–0.008 , a range slightly more metal-rich than the one provided by stars .
Comparing our PN-to-stellar values to surveys for other dwarf Local Group galaxies , Phoenix appears as an outlier .