Boxfishes (Ostraciidae) are known to be benthivores and mainly consume sessile organisms on reefs, such as tunicates. Ascidian tunicates contain various toxins and seldom suffer from predation by reef fishes, except for boxfishes. However, the importance of ascidian tunicates has not been sufficiently examined in the feeding ecology of boxfishes. We conducted field surveys to investigate the feeding habits of the white-spotted boxfish Ostracion meleagris on the reefs of southern Japan. Photosymbiotic ascidians predominantly contributed to the boxfish diet, and observed colonies of ascidians were bitten frequently by the boxfish during the survey. During the day, the feeding boxfish moved within their home ranges in a rocky, shallow zone of the studied reefs, which harbored photosymbiotic ascidian colonies of the family Didemnidae at higher densities than in the surrounding zones, including the spawning sites that were located hundreds of meters offshore. Boxfish home ranges overlapped considerably, but intraspecific agonistic interactions rarely occurred among the females, likely due to the abundance of ascidian colonies. No other types of fish were observed to make attempts to feed on the ascidian colonies on the reef throughout the study period, except for a congener Ostracion cubicus. These results suggest that the boxfish strongly rely on the photosymbiotic ascidians as a less-competitive food resource, and the limited distribution pattern of photosymbiotic ascidians in shallow water near shore can be an important factor in promoting a spawning migration in the boxfish.

盒鱼（Ostraciidae）是底栖动物，主要消耗礁上的无柄生物，例如被膜。海鞘被膜含有多种毒素，除了盒鱼外，很少受礁鱼的捕食。然而，在箱形鱼类的摄食生态学中，尚未充分检查到海鞘被膜的重要性。我们进行了实地调查，以调查白斑箱鱼Ostracion meleagris的摄食习惯在日本南部的珊瑚礁上。光共生海藻主要是对盒鱼饮食的贡献，在调查过程中，观察到的海星菌落经常被盒鱼咬伤。白天，摄食盒鱼在其研究范围内的岩石浅层区域内移动，该区域内藏有双翅目科的光共生海藻殖民地，密度高于周围区域，包括成百上千个产卵点。离岸米。Boxfish的宿主范围有相当大的重叠，但是雌性之间的种内激动作用很少发生，这可能是由于海鞘集落的丰富。在整个研究期间，除同源鱼类外，未观察到其他类型的鱼类试图以珊瑚礁上的海鞘殖民地为食隔骨。这些结果表明，盒鱼强烈依赖光共生海藻作为竞争性较弱的食物资源，光共生海藻在近岸浅水区的有限分布模式可能是促进盒鱼产卵迁移的重要因素。