Cellular models are an important tool for studying human heart disease. To date, many research groups focus on mouse models, but murine cardiac physiology is different from human cardiac physiology. Interestingly, recent data suggests the electrophysiology of fish cardiomyocytes largely resembles that of humans (Brette et al. 2008), opening up the possibility of the fish to become a good model system to study heart disease. Recently, a fast and cost-effective in vitro heart model system has been developed (Grunow et al. 2010, 2011, 2012). The model is a 3D cell cluster which beats spontaneously and is generated from fish larvae. Morphological and molecular characterisation of the 3D in vitro heart model revealed high similarities to human heart in terms of beat rate, drug responses and structural morphology (Grunow et al. 2011).The present work uses electrophysiological techniques to characterize underlying ion currents in myocytes acutely isolated from the 3D in vitro heart model. Our results suggest that the 3D in vitro heart model has high potential