Castres has validated its ticket for the final phase of the Top 14 and joins the UBB and Montpellier already guaranteed to participate in the playoffs since yesterday.
The CO took over Perpignan, 13th and still a play-off one day before the end of the championship.
Botitu scored twice (8th, 40th + 2) and Nakosi (71st), after a superb collective action, allowed the Castres to record the offensive bonus point and secure their place in the top 6.
For the Catalans, who are 3 points behind Brive (12th), they will have to win in the last meeting if they want to avoid a dam.