Posing a significant threat to the native biodiversity in Japan, specifically that of threatened aquatic insects, some alien fishes, such as the bluegill, have become the reason for strict prohibitions. However, recently, 10 years after the law against their release into the wild has been adopted, its first infringement is reported by Japanese researchers in the open-access journal ZooKeys. Curiously, the case was initially exposed on Twitter by an undergraduate student.