Bradford ran out clear winners in an engage Super League match which was a lot closer than the score suggests.
The home side led 10-0 early on at The Jungle but four Bulls tries in the final eight minutes of the first half put the visitors in command.
And when Michael Platt, Ben Jeffries and Simon Finnigan all added efforts in the second half, the struggling Tigers never looked like coming back.
The home side opened the scoring as early as the third minute when 18-year-old teen sensation Joe Westerman broke the Bulls ranks and sent centre Michael Shenton over in the corner but Kirk Dixon missed the conversion.
Michael Wainwright had two tries disallowed, one of which saw the winger sprint the length of the field only to be called back by the match official.
But they did increase their lead in the 18th minute when full-back Ryan McGoldrick managed to get on the end of a clever grubber kick from Luke Dorn, with Dixon adding the two points.
Bradford responded when Jeffries, who was picked ahead of Iestyn Harris, cut the home defence open before sending Paul Sykes over to reduce the deficit. The usually reliable Paul Deacon missed what looked a simple conversion.
Jeffries almost had a try of his own shortly after but David Solomona's pass which released the stand-off was adjudged to have been forward.
Bradford pulled level in the 26th minute when incisive running and a cleverly timed pass from loose forward Sam Burgess gave Terry Newton the opportunity to score and he duly obliged with Deacon converting.
But Tigers put themselves back ahead on the half-hour mark with a moment of sheer brilliance from Westerman.
Dorn threw a long pass to the youngster, who dummeyed his way through a hole in Bradford's defence and sprinted home from distance - Dixon failed to convert.
Burgess piled over before the break with Deacon kicking the visitors into the lead in the 34th minute.
Second row Glenn Morrison helped himself to his sixth try of the season two minutes later following an intelligent kick from Jeffries and Jamie Langley added another with Deacon converting both.
The hosts put themselves back in the game in the 52nd minute after centre James Evans was sent to the sin bin for persistent offending.
Tigers threw the ball wide with Dorn and Stuart Donlan combining well in midfield before Wainwright touched down in the corner. Westerman then struck a fine conversion to move the Tigers to within 10 points of Bradford.
However, Bulls put the match beyond doubt with tries from Platt, Jeffries and Finnigan - Deacon converting all of them.
Dorn added a late consolation for Castleford but the Super League new-boys remain rooted to the foot of the table.