Universal Forwarder Fishbucket growing.

Hi All, The UF (6.6.2) on our AIX server has an issue where the fishbuckets are growing in size 3gb + even after setting the file_tracking_db_threshold_mb = 500. Is there a way to invoke a retirement policy? If we reduce the value to 200, I understand this will in turn create smaller multiple buckets not necessarily solve the issue but will those buckets age out sooner. Thanks