The aim of this paper is to present review of the invasive diseases which currently appear in the inland, exotic aquarium ornamental fishes. Also, analysis of possible sources for responsible parasites, which can invade ornamental fish breeding at different stages, was performed. It has been found that at least some representatives of fish, that originate directly from tropical lakes and rivers, could be carriers of parasites. They can multiply rapidly in aquaria densely populated with permanently stressed fish. This, in turn, leads to development of pathological lesions and clinical signs in fish. Ornamental fishes farmed in breeding centres in tropical countries can be also a source of infection. For many years, imported fishes which were the carriers of parasites were kept together in common aquaria. Nowadays, some pathogens have adapted to aquarium environment and permanently appear in hobby aquaria. Actually, the same etiological agents could be found in aquarium fishes all over the globe. Basing on the results of our investigations together with thorough analysis of other authors references, we have presented the parasitic diseases that are considered as causes of major losses in ornamental fish industry: piscinoodinosis, spironucleosis, ichtiobodosis, tetrahymenosis, ichtioftiriosis, tetraonchosis, gyrodactylosis, capillariosis, oxyuridiosis and camallanosis.