Abstract The Asian fish tapeworm, Bothriocephalus acheilognathi Yamaguti, 1934, was detected for the first time in breeding of discus fish Symphysodon discus (Perciformes, Cichlidae), a popular South American cichlid. In examined samples, the adult and juvenile cestodes of B. acheilognathi with mean intensity of infection 30 (range 19 - 47) individuals per fish were found. The infected fish displayed acute behavioral symptoms. Mortality was significant; it reached almost 80 % in youngest age categories. As treatment, praziquantel immersions in dose 2 mg per liter were well tolerated and efficacious. The risk of spreading pathogens via imported fish is actual menace for ornamental breeding fish, therefore, thorough quarantine and prophylactic measures needs to be done by all fish imports and introductions. Import and subsequent release of infected ornamental fish into freshwater ecosystems may represent serious risk for spread and establishment of the parasite in native fish species. This case study illustrates that ornamental fish play also a key role in national and international movements of parasites in freshwater habitats.