Fideris has a population () of . , 7.2% of the population are resident foreign nationals. Over the last 4 years (2010–2014) the population has changed at a rate of −4.24%. The
birth rate in the municipality, in 2014, was 8.5, while the
death rate was 5.1 per thousand residents. In 2014 there were 243 private households in Fideris with an average household size of 2.36 persons. Of the 210 inhabited buildings in the municipality, in 2000, about 62.9% were single family homes and 15.2% were multiple family buildings. Additionally, about 42.9% of the buildings were built before 1919, while 11.4% were built between 1991 and 2000. In 2013 the rate of construction of new housing units per 1,000 residents was 3.43. The vacancy rate for the municipality, , was 1.59%. Colors= id:lightgrey value:gray(0.9) id:darkgrey value:gray(0.8) ImageSize = width: auto height:200 barincrement:45 PlotArea = top:20 left:40 bottom:20 right:35 AlignBars = justify DateFormat = x.y Period = from:0 till:700 TimeAxis = orientation:vertical AlignBars = justify ScaleMajor = gridcolor:darkgrey increment:100 start:0 ScaleMinor = gridcolor:lightgrey increment:20 start:0 PlotData= color:yellowgreen width: 35 mark:(line,white) align:center bar:1850 from:start till:460 text:"460" bar:1860 from:start till:437 text:"437" bar:1870 from:start till:369 text:"369" bar:1880 from:start till:398 text:"398" bar:1888 from:start till:405 text:"405" bar:1900 from:start till:363 text:"363" bar:1910 from:start till:354 text:"354" bar:1920 from:start till:407 text:"407" bar:1930 from:start till:406 text:"406" bar:1941 from:start till:480 text:"480" bar:1950 from:start till:524 text:"524" bar:1960 from:start till:549 text:"549" bar:1970 from:start till:554 text:"554" bar:1980 from:start till:492 text:"492" bar:1990 from:start till:586 text:"586" bar:2000 from:start till:586 text:"586" bar:2010 from:start till:613 text:"613" bar:2014 from:start till:587 text:"587" ==Languages==