Amidst the COVID-19 pandemic we have observed drastic human behavioural changes from a disease threat. Indeed, disease drives the evolution of transformational and spectacular behaviours in fishes as it does in terrestrial animals. In this presentation I will talk about how fishes manage diseases through self-remedy, by utilizing natural resources around them. Some of these behaviours are well known while others are almost entirely unexplored. These behaviours include mass migrations, ‘behavioural fever’, zoopharmacognosy, fish visiting the doctor (=cleaning interactions) and bizarre interspecific associations - you’d have to be driven crazy by external parasites to approach a shark to rub on their skin. The need for self-remedies to prevent or manage disease affects all individual organisms. It has driven considerable complexity in fishes and is in such demand in nature that many species have made treating other organisms their specialisation.