The criteria for accepting that a fish was diseased and positive for marine flexibacteriosis involved two parts: method of recovery and quantification of colonies and cells. T. maritimum had to be recovered from mortalities by culture and in smears by IFAT as these methods are more specific than Gram stain. The minimum abundance of cells required for a positive result was 10–50 bacteria per 25 fields for IFAT and Gram stain. The minimum abundance required to record a positive result in culture was growth of colonies extending to the first streaking lines.