infects a range of hosts, including fish, shellfish, and echinoderms. Infection with this pathogen has led to significant economic loss in several cultured species, including the sea cucumber (). Thus, there is an urgent need to understand the pathogenesis of . The virulence of a pathogen is partly a function of its adhesion properties. Adhesion depends on cell surface hydrophobicity and biofilm formation. The hydrophobic cell surface provides an advantage to the bacteria by increasing resistance to phagocytosis or by favoring colonization of mucosal or connective tissue in wounds and endocarditis in bacteria. We evaluated the hydrophobicity and biofilm formation in . We also evaluated the effect of culture constituents, culture time, growth medium, and the concentration of glucose on biofilm formation. We compared the sensitivity of planktonic cells and resuspended AP622 biofilm cells to gentamycin sulphate. Last, we quantified the motility of the flagellum and measured pill and cell surface hydrophobicity using tests for salt-aggregation (SAT) and microbial adherence to hydrocarbons (MATH). AP622 possesses a high ability to form a biofilm. The biofilm formation cycle was 24 h in length and the optimal formation conditions consisted of polyvinyl chloride (PVC) and LB medium with 0.5% glucose. Swarming and twitching motilities played an important role in biofilm formation. The resistance of resuspended biofilm bacteria to antibiotics was significantly higher than intimes higher than in planktonic bacteria. exhibiting strong hydrophobicity, could agglutinate at a concentration of 0.6 mol/L ammonium persulfate, and the adhesion partition to liquid hydrocarbons was >50%. In conclusion, the hydrophobicity and biofilm formation properties suggest that AP622 has strong adhesion properties. Resistance to antibiotics as a result of biofilm formation will reduce the effectiveness of treatments in aquaculture facilities. Thus, cell surface hydrophobicity and biofilm formation play an important role in the pathogenesis of .