<p>Barnacles substantially damage mangrove seedlings, which has drawn widespread attention to their prevention in recent decades. However, the effects of barnacle control on the growth of mangrove seedlings are still unclear. To this end, a 102-day barnacle prevention experiment was conducted on <i>Kandelia obovata</i> seedlings using different formulations of waterproof adhesive, and the changes in growth characteristics of <i>K. obovata</i> seedlings were analyzed. The results showed that all three antifouling coatings effectively prevented barnacles from attaching to the trunk of <i>K. obovata</i> seedlings, and waterproof adhesive containing azadirachtin had the highest efficiency. Due to the ever-increasing number of attached barnacles, the growth of <i>K. obovata</i> seedlings was mainly reflected in a diameter increment rather than a height increase, primarily to endure stress or storms and avoid being broken. This study provides ideas for developing novel materials to prevent barnacles and promote the ecological restoration of artificial mangroves.</p>