While popdc1 larvae with a normal morphology or a moderate morphological phenotype (spinal curvature and/or pericardial effusion) were selected in the current study, and larvae displaying a severe morphological phenotype were excluded, a general decline in health may in part account for the observed effects on the heart’s electrophysiology and intracellular Ca2+ handling, rather than cardiac-specific effects. This evidence concerns the gene POPDC1 and pericardial effusion.