Patrick Doherty, Clooncon West, Glenamaddy was also charged with assaulting and causing harm to Gerard Costello of Cloonculane, Glenamaddy.
Mr Fahy was fatally stabbed early yesterday in Glenamaddy.
At a special Sitting of the District Court in Roscommon Sgt Mick O'Driscoll said that when cautioned Mr Doherty replied he had nothing to say to both charges.
Inspector Frank Nicholson asked that Mr Doherty be remanded in custody to Harristown District Court in Castlerea on Friday.
Defence solicitor Tom O'Donoghue said he had no objection to this.
Judge Geoffrey Browne remanded Mr Doherty in custody until Friday and granted him free legal aid.
The scene outside the pub where the incident occurred is still being preserved for further technical examination.
Gardaí in Tuam have renewed their appeal for witnesses.
