Décroître belong to the 3rd group. Décroître is a common french verb.
Décroître is conjugated the same way that verbs that end in : -oître
Décroître is conjugated with the two auxiliaries être and avoir.
Décroître verb is
Décroître is a french third group verb. So, this verb is irregular and do not follow a regular conjugation pattern like first or second group verbs. Follow this link to see all the endings of the conjugation of most of the third group verbs : conjugation rules and endings for the second group verbs.