The term "fight fair" seems an oxymoron to me. Odds are that if one or all parties are being fair, then there is no fight. If one or all parties respectfully express differing opinions, then it's hard to work up a to a brawl or harsh verbal sparring. It usually takes one party throwing a verbal or physical punch and another party punching back for the situation to be a fight. Otherwise one might label it an exchange of information or, in the case of one physical punch being thrown, but not reciprocated, assault.