Crusaders half-back Michael Witt has been suspended for one match after punching Castleford's Richard Mathers.
Witt, who pleaded guilty to the Grade B offence, was also fined £300 after the RFL disciplinary committee ruled he had behaved in a manner contrary to the spirit of the game.
The incident happened in the 16th minute of their 56-16 defeat on Sunday.
Witt was one of three Crusaders players sin-binned as Iestyn Harris's side suffered a sixth straight reverse.
Tigers duo Nick Fozzard and Willie Isa both received cautions for dangerous play in the same match.
Huddersfield's Luke O'Donnell, Warrington forward Ben Westwood and Tony Clubb (Harlequins) have also been given cautions which will remain on their records.